mobile high frequency screen plants - astec

mobile high frequency screen plants - astec

The site navigation utilizes arrow, enter, escape, and space bar key commands. Left and right arrows move across top level links and expand / close menus in sub levels. Up and Down arrows will open main level menus and toggle through sub tier links. Enter and space open menus and escape closes them as well. Tab will move on to the next part of the site rather than go through menu items.

These screens offer ideal gradation control for reclaiming fines in both wet and dry applications. Pair that with the flexibility and mobility of the track unit and producers can quickly and easily produce the material they need.

lxi digitizers for multi-channel high-frequency signal capture and analysis | news | spectrum

lxi digitizers for multi-channel high-frequency signal capture and analysis | news | spectrum

The entry level DN6.221 models offer versions with 12, 16, 20 and 24 channels, with each channel capable of sampling electronic signals at rates up to 1.25GS/s. The top-of-the-line DN6.225 series increases performance by allowing up to 12 channels to sample at 2.5GS/s or 6 channels at 5GS/s.

The digitizerNETBOX products are complete instruments that include all the tools necessary to capture, digitize and analyze electronic signals. Simply connect the instruments to a host computer (e.g. laptop or workstation) and start up Spectrum's SBench 6 software. Standard with every unit, SBench 6 lets you control all the digitizers operating modes and hardware settings from one simple, easy-to-use, graphical user interface.

The software also has a host of built-in features for waveform display, data analysis and documentation. Acquired and analyzed waveforms can be stored and exported to other devices or other software programs in a variety of formats such as MATLAB, ASCII, binary and wave.

Each channel of a DN6.22x series digitizer features its own analog-to-digital converter (ADC), large acquisition memory (1 GSample/channel) and independent signal conditioning circuitry. The ADCs are clocked synchronously to ensure that inter-channel timing measurements can be made with the best possible accuracy as well as maintaining a constant phase relationship.

Front-end amplifiers allow input signals to be correctly scaled, so that the digitizers can utilize the ADCs complete 8-bit dynamic range. Programmable full scale ranges (into 50 termination) go from 200mV up to 2.5V or optionally from 40mV up to 500mV. The flexible signal conditioning also includes AC/DC coupling and programmable input offset.

The DN6.221 models, with 1.25GS/s sampling rate, are matched with amplifiers that deliver over 500MHz of bandwidth, while the DN6.225 models increase this to 1.5GHz. The combination of fast sampling rate, wide bandwidth and long acquisition memory enables the digitizers to capture long, complex, high-frequency signals. It also makes it possible to characterize and measure fast events that go down into the nano- and sub-nanosecond timing ranges.

Designed to acquire and analyze a wide range of signals, the digitizerNETBOX instruments also include a host of acquisition modes. Single Shot mode is available for capturing transient events and Multiple Recording stores numerous signals that arrive in bursts or packets. Gated Sampling synchronizes the acquisition with another event, while ABA mode mimics the operation of a chart recorder enabling segments with fast and slow sampling rates to be recorded simultaneously.

Each channel of the digitizerNETBOX, as well as two external inputs, can act as a trigger source with the capability of combining all sources by AND/OR logic functions. The logic feature makes it possible to trigger only when you see specific patterns on the inputs, greatly simplifying complex trigger situations. Trigger events can also be date and time stamped so that you know exactly when, and how often, they occurred.

All DN6 series instruments feature an industrial chassis with integrated cooling, a replaceable dust filter and low noise power supplies. Front-panel SMA connectors are used for the channel inputs, external clock and external trigger, while LED lights provide a visual indication for the power, trigger and LAN status.

Based on the LXI instrumentation standard (following the LXI Device Specification 2011 rev. 1.4), the digitizerNETBOX products are also designed for use in automated testing and remote applications. Full remote control is achieved through a simple GBit Ethernet port, which allows connection to any PC or local area network (LAN). With their high channel density, the products are well matched to applications where arrays of receivers, sensors, detectors, rectifiers, antennas and other electronic devices are used and tested.

The products are fully programmable and come with drivers that allow users to write their own control programs in a host of popular programming languages, including C++, Visual Basic, VB.NET, C#, J#, Delphi, IVI, Java and Python code. Third party software support is also provided for LabVIEW, LabWindows and MATLAB.

The DN6.22x digitizerNETBOX products are available for immediate delivery. All units are shipped factory tested and include Spectrum's SBench 6 Professional version software, support drivers and a 5 years manufacturers warranty. Technical support, including software and firmware updates, is available free of charge.

high frequency screen or feeder | general kinematics

high frequency screen or feeder | general kinematics

The GK High-Frequency Screen or Feeder equipped with the innovative, patent-pending Structural Springs, is a fiscally responsible solution for powder and bulk processing. Structural Springs also function as legs to create a simplified design. The smaller natural frequency motor provides a more cost agreeable solution compared to brute force.

arduino high speed oscilloscope with pc interface : 8 steps - instructables

arduino high speed oscilloscope with pc interface : 8 steps - instructables

Transfered to a PC, these points can be accurately plotted against time.This Instructable will show you how the analogue input can be repeatedly added to a 1000 byte buffer and then transferred to a serial monitor. The data is collected using a high frequency interrupt, whose period can be accurately determined. The frequency can be altered to produce a range of possible periods.

I have written two slightly different versions for the Arduino data capture. One utilizes software triggering for when an accurate change in voltage is required, before the oscilloscope triggers. The second, uses hardware edge triggering based on an interrupt on Arduino pin 2. The hardware version runs a little faster at the highest frequency.

I did a minor rewrite today (31/8/2014). The PC interface now includes the option to set the voltage reference to accurately reflect the real value of the Arduino "5V" line. There are also small adjustments to the Arduino software.

As of 6/9/2014 I have developed a slightly modified version of the Software Triggered version which runs at up to 227.3 KHz on my Mega, using register commands to directly control single conversion reads. If there is interest, let me know.

In a fast run the arduino will wait for a serial response of any character for 1500 milli seconds after outputting data. If a character is received (a handshake), the Arduino will immediately gather more data. If 1500 mS is up more data is recorded, regardless.

Set the number of bits used in the analogue port capture. For speed 8 bits are read. The ADLAR bit controls the presentation of the ADC conversion Write one to ADLAR to left adjust. Otherwise, the value is right adjusted. This has an Immediate effect on the ADC Data Register.

Essentially if no triggering is selected, the adc interrupt is enabled and data is captured immediately. If triggering is selected an interrupt on digital port 2 is used to enable the interrupt on the adc port 1.

The flag triggered controls whether the digital port 2 interrupt starts the analogue port 1 interrupt . When triggered is false the interrupt starts the adc interrupt when it detects an edge in the analogue input.

2) For windows 7/8 copy the address of the folder in which you extracted the application. If you right click on the address in the bar at the top of windows file explorer you will find the option to copy the folder address.

Select frequency and you will get the square wave frequency. The first estimate is based on the rising edges at the midpoint of the voltage range. The second is based on a technique outlined in an excellent article at:

This bipolar converter is interesting. In the past I have designed these with an op amp, precision voltage reference and lots of trim pots. This design was inspired by an article which was supported by Ronald Michallick of Linear Applications. He suggested using a three resistor bridge and supplied an excel spreadsheet to design it.

My 20Mhz version was developed from work done by Bob Davis , who realised that the Arduino was never going to be able to directly measure significantly high data rates. His elegant solution was to use an external ADC and a fifo to capture the data at a high clock frequency. Once captured, the fifo flags the data capture completion and the Arduino transfers the data at it's clock frequency.

The 20 MHZ oscilloscope uses the tlc5510a and a 2K fifo (IDT7203L12TPG). By using a 2K fifo I am able to trigger by downloading all the data to the mega and then processing the trigger point in memory. Once found, I upload the subsequent 1000 values to the PC. Triggering is therefore rock solid. I have edge and level triggering on either voltage slope. A simple potentiometer is used to set the trig point.

3) Buffered, with the input dropped across 4 matched 22K resistors. This produces equal attenuations. The drop is passed through the excellent NE5534P 10MHz low noise op amp, configured as a follower... and then to a 4V3 zenner. This produces input ranges of 0 to 4, 5.33, 8 and 16V.

Hello DavidI have tried the program on mega I have boosted your image signal at 30KHZ.The signal is somewhat distorted. The extra frequency at 30KHZ is more distorted.If you can write me a program in which sampling shows me high frequencyProgram without programming a LED screen or connecting with a PC means a program that deals with ADC fast onlyThank you DavidI'm sorry to take your time.

// Defines for setting register bits#ifndef mysbi#define mysbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))#endif#ifndef mycbi#define mycbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))#endifconst byte testpin = 10;// connect pin10 to analogue 0 for testing// defines for pwm output on testpin (pin 10 specific on mega!)#ifndef fastpwm#define fastpwm (TCCR2B = (TCCR2B & B11111000) | B00000010)#endif#ifndef slowpwm#define slowpwm (TCCR2B = (TCCR2B & B11111000) | B00000100)#endif#define BUF_SIZE 1000uint8_t bufa[BUF_SIZE];const byte check = 1<= 237.2 KHz !!!!!*/void startad(){unsigned long starttime, endtime;startit = false;cli(); // disable interruptsmysbi(ADCSRA,ADEN); // enable ADCsei(); // enable interrupts// First conversion- initialises ADCmysbi(ADCSRA,ADSC); while((ADCSRA & check)== check); // wait for ADSC byte to go low// New conversion and use current ADCSRA value for triggerbyte startit = ADCSRA | check;ADCSRA = startit;starttime = micros(); for (unsigned int i = 0; i < BUF_SIZE; i++){ // wait for conversion while((ADCSRA & check)== check); bufa[i] = ADCH; // New conversion ADCSRA = startit; }endtime = micros();cli();mycbi(ADCSRA,ADEN); // disable ADCsei();elapsed = endtime - starttime;writeit = true;}

Hellothank you my friendBut I'm for the purpose of understanding ADC fast even in Arduino Mega and understanding the sampling method of 200KHZ so that the display signal is clean, so you will be able to correct the errors that are in itIt will download you the program you createdIt can be adjusted to take samples from 0-200KhzThank you-This is the program:#include "TimerOne.h"#define FASTADC 1// defines for setting and clearing register bits#ifndef cbi#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))#endif#ifndef sbi#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))#endifvolatile int value[300]; // variable to store the value coming from the sensorvolatile int i;volatile int p = 0;void setup(){ Serial.begin(9600) ;#if FASTADC // set prescale to 16 sbi(ADCSRA, ADPS2) ; cbi(ADCSRA, ADPS1) ; cbi(ADCSRA, ADPS0) ;#endif Timer1.initialize(10); Timer1.attachInterrupt( timerIsr1 ); // attach the service routine here}void timerIsr1() { if (p == 0) { for ( int i = 0; i < 300; i ++) { value[i] = analogRead(A0); // delayMicroseconds(2); }; p = 1; }}void loop(){ for (i = 0; i < 300; i++) { Serial.println(value[i]); delayMicroseconds(2); }// delayMicroseconds(2); p=0;}

Very nice! One option (for about the same cost) is to use the Teensy 3.1 (http://www.pjrc.com/teensy/teensy31.html) which is a lot faster, especially the A/D conversion (I think it can be done with DMA).

The teensy appears to be 3.3V based. So the Arduino and PC program would run incorrectly, without modification. I have no idea whether the same interrupts and register controls are available on the Teensy. The serial route out is also unclear to me. Not exactly a drop in solution?

Indeed, with the Teensy 3.1 running at 72 Meg and with 64k RAM it seems to me that this beautiful PC interface could be done justice!! We could be looking at a scope fast enough to debug normal Arduinos!!

the ultimate guide to the frequency separation technique | fstoppers

the ultimate guide to the frequency separation technique | fstoppers

Chances are you have already learned what Frequency Separation (FS) technique is, as it became mainstream in the past few years. However, many FS technique users actually know very little theory behind it, thus have little control over its implementation. I've set out to research and collect all the important and useful information about it, so we can together learn how to become better at it.

After we look at the slightly geeky results of my research (my sources at the end of this article), I would also like to share with you a few practical ways of its smart implementation with the help and advice from my friends: commercial photographer from Moscow, Aleksey Dovgulya(you may remember Aleksey from myShooting With Mixed Studio Lightingarticle)and Toronto-based photographer & retoucher Michael Woloszynowicz.

Frequency Separation technique is virtually a process of decomposing of the image data into spatial frequencies, so that we can edit image details in the different frequencies independently. There can be any number of frequencies in each image, and each frequency will contain certain information (based on the size of the details). Typically, we break down the information data in our images into high and low frequencies.

Like in music any audio can be represented in sine waves, we can also break up an image into low and high frequency sine waves. High frequencies in an image will contain information about fine details, such as skin pores, hair, fine lines, skin imperfections (acne, scars, fine lines, etc.).

Low frequencies are the image data that contains information about volume, tone and color transitions. In other words: shadows and light areas, colors and tones. If you look at only the low frequency information of an image, you might be able to recognize the image, but it will not hold any precise detail.

You may have seen this optic illusion that exploits the frequency separation principle. If you look at this image from a normal distance from your computer while reading this article you will see Albert Einstein's photo. Now, get up and walk away from your screen. Look again. Who do you see now?

Essentially, this image is a combination of photos of Marilyn Monroe in the low frequency layer and Einstein's in the high frequency layer. When you look at the image from a close distance you see the high spatial frequency image (Einstein), the fine details, the outlines of his facial features. Once you walk away, your eyes will adjust - the "low pass filter" of your vision will kick in - and you will see the low spatial frequency image (Marilyn Monroe).

Within the digital photography editing craft, the separation of spatial frequency data in images can be utilized for skin (and not only) retouching. While there are a number of ways to implement the Frequency Separation technique, the steps you take to get to the final result will define the amount of time spent and the quality of the outcome.

Before we begin, I want to make a quick note regarding the use of the High Pass filter in the FS technique. When it is used to separate the image into high and low spatial frequencies, the results are inaccurate. In other words, after the separation your image data is slightly skewed, so you compromise the quality of the outcome before you even begin retouching.

2. With the Low Frequency layer selected, run the Gaussian Blur filter and choose Pixel Radius with which all the fine details will be blurred. We turn off the visibility of the High Frequency layer, so that we can better see how our choice of Pixel Radius affects the entire image. After you've applied the Gaussian Blur filter, turn the High Frequency layer's visibility back on.

From this point on, every retoucher and photographer chooses his or her preferred tools to work their magic. Basically, we aim to soften and even out color and tone transitions on the Low Frequency layer, without affecting skin texture, which was captured and preserved on the High Frequency layer.

You will normally hear that the Clone Stamp tool or the Healing Brush tool with Current Layer Sampling setting and very low Hardness are the tools to work on the Low Frequency layer; the same tools only with very high Hardness settings are your High Frequency layer tools.

Check out my old video where I only used the Healing Brush tool. I've changed my ways drastically since then, but we'll talk about that later. The goal of this video was to show how fast this technique can be, so you will see a countdown clock at the top of my screen - 25 minutes, boom!

If that's all you've been doing so far, let me share a few more strategies that I've learned from my own experience and from my talented friends. We all love experimenting and coming up with new ways to use ordinary tools and techniques, so here's what we've come up with so far.

As I mentioned before, when High Pass filter is applied to the High Frequency layer in place of the Apply Image function, it gives you an imprecise final image where the brightest pixels are usually grayed out. According to my friend Aleksey, it actually plays out well when you are retouching skin with a bit of overexposed highlights on it. They get toned down and the skin looks more matte as a result. Other parts of the photo where you wouldn't want the highlights to be muted down (such as specular highlights on the lips, catchlights in the eyes, etc.) can be easily covered up with a Layer Mask.

Aleksey also insists that it's a very quick method, and should be used along with the Apply Image FS algorithm when appropriate. He explains that using the High Pass filter gives you more control in deciding what information belongs on the High Frequency layer and what should be blurred out on the Low Frequency layer. This way, after you've performed the separation, your further retouching should be much faster and precise.

For example, we've got this photo to retouch. There are some problems that should be taken care of on the Low Frequency layer such as shadows, larger areas of colors and tones that we need to soften or remove. On the other hand, there are also little blemishes on the skin texture, which should be handled on the High Frequency layer.

To separate spatial frequencies with the High Pass filter, we need to create two duplicate layers, just like in the Apply Image approach. The top layer will contain our High Frequency image data and the bottom layer will be our Low Frequency layer.

At this point, we need to figure out how much fine details will be taken to the High Frequency layer, and what will be smoothed out on the Low Frequency layer. As soon as we start seeing excessive tonal transitions, bulky textures and volumes we should stop - that will be the limit of what goes onto the High Frequency layer.

And at 3.5px Radius we get the right amount of fine details, so this will be the number we select. Click OK, and then change the High Frequency layer's Blending Mode to Linear Light and Opacity to exactly 50%.

Now turn the visibility of the High Frequency layer off, and apply the Gaussian Blur filter to the bottom layer - Low Frequency - with the same Pixel Radius we have just selected in the High Pass filter dialog.

On the Low Frequency layer you can use either the Healing Brush (very soft, Sampling set to Current Layer), Clone Stamp (very soft, lower Opacity, Sampling set to Current Layer) or Simple brush tool to even out colors and tones. I personally have recently found that working with a simple Brush on lower Opacity works the best for me. I do sometimes still use the Healing Brush tool, but I never use the Clone Stamp tool on the Low Frequency layer.

On the High Frequency layer you can use all of the same tools, only your brushes and the Clone Stamp tool should have higher Hardness settings and higher Opacity percentage. I personally prefer the Clone Stamp and hard Healing Brush tools for working on the High Frequency layer. Those tools help me to avoid smudging and softening skin texture.

According to my crafty friend, this skin retouch took him only a few minutes because the frequency spatial data of the image was properly separated. All the texture remained intact on the top layer - High Frequency layer - and the colors and tones were quickly evened out underneath it.

"The Apply Image and High Pass approaches of separating frequency spatial data of an image are the two main ways of how I use the FS technique," says Aleksey, "Apply Image setup is more accurate, but the High Pass setup is quick and helps me to not only customize the separation of skin texture from underlying colors, but also tone down "hot" highlights on the skin. I always go for the High Pass setup when I need to do a quick retouch, especially when evening out skin. It is really helpful to be familiar with and practice both approaches."

You can add an additional duplicate layer of the original image between the High and Low Frequency layers (in either setup). Then apply Surface Blur to it - Radius and Threshold numbers will always be different for different images. Ive never had to use Surface Blur for anything in my work before, so Aleksey explained to me the correct way of selecting Radius and Threshold settings:

This method is super quick and can be used as the preparation step before you get down to retouching. It very well maybe the only step that you need if your models skin is already well-prepared for the shoot, i.e.great makeup and skin to start with.

Set up High and Low Frequency layers as many times as you need to solve problems in your current retouch. I personally do at least 2-3 rounds of Frequency Separation, and I also Dodge & Burn the problems that remain.

Aleksey suggests that the best results can be achieved when you create custom High and Low Frequency layers (just like he showed us earlier) for each part of the face that needs doctoring. Your Radius settings for the High Pass and Gaussian Blur filters most likely will be different for each part of the face. It is a little more elaborate approach, but custom settings will help you achieve the best results for each part of the image.

Remember, than you can use the Clone Stamp, Healing Brush tools and a simple brush to fix skin problems on the Low Frequency layer, as well as on the High Frequency layer. Watch the Hardness and Opacity of the tools, and the Sampling settings should always be under control as well.

Each of these tools will be helpful in some situations, so you shouldn't pick up just the one tool you prefer for everything. Try and practice working with each one of them and see where and when they give you the best results.

I personally use custom settings for the High Pass setup, so I don't need an Action for that. But in many situations, when the subject's face is not very close to the camera (the skin texture doesn't require a lot of doctoring) I use a Frequency Separation Action that I recorded for myself. I mainly work in 8-bit color depth, so my action is for 8-bit images. You can break it down and re-create one for 16-bit photos using the settings I've mentioned above.

Another trick that I came up with in my experiments is enhancing skin texture by duplicating the High Frequency layer. I usually first fix all the most visible blemishes on the original High Frequency layer, then duplicate it and cover with a black Layer Mask. I then paint with a soft white brush (low Opacity) over the areas where I want the texture to be a little more pronounced.

To make it even more fun, you can actually borrow parts of the High Frequency layer with the more pronounced texture and apply them to the areas where the texture is too soft or has been destroyed by your previous manipulations, suggests my friend and fellow-photographer and retoucher Michael Woloszynowicz of VibrantShot.com. He also mentions that he uses the Free Transform tool to re-shape those pieces when the skin texture direction or forms dont match those of the areas, which they are applied to.

Theres no one right way as to what technique should be used first and how many rounds of each should be applied. I sometimes start with the FS technique and finish up evening out the skin with Dodging & Burning. Sometimes it makes sense to soften large shadows with Dodging first and then only retouch skin texture on the High Frequency layer.

Its always different because every image is unique. But it will definitely help to know and practice both techniques, so that you can easier determine which one will solve the problems you stumble upon better.

"I typically use the FS technique for color changes and Dodge & Burn for luminance changes. If you try to make drastic luminance changes with FS, I find that it can reduce texture as your new tones will blend with the light or dark tone of the High Frequency layer. Dodging & Burning, on the other hand, will darken or lighten both the high and low frequency data, thus avoid this issue," saysMichael Woloszynowicz.

And of course, thanks again to my photographer-friends Aleksey Dovgulya and Michael Woloszynowiczfor sharing their methods and tips with us!Aleksey is coming to Los Angeles in January 2014, so we can finish ourBeauty & Fashion Photography: Go Pro digital book - check it out and sign up for our newsletter to get notified when it's ready!

Julia is a Los Angeles based internationally published Beauty & Fashion photographer, digital artist, retoucher and educator. An International College of Professional Photography (Melbourne, Australia) graduate. Retouching Academy founder and Editor-in-Chief.

What I love about Julia's articles (as well as her ebook) is how she manages to stuff so much information in her texts that you gotta read at over and over again to absorb it all hahahaha THanks Julia!

Hi Julia. I have read that using different blurring techniques can produce more accurate frequency separation results. Two alternate that I know of is Surface Blur (takes way too long to render) and Dust and Scratches (the method that I use).

Also, I'm trying to to wrap my head on a variant to FS called asymmetric frequency separation, which results in a completely gray-scale high-frequency separation. My issue with this seems to be that certain color shift gets introduced when healing/clonging. Have you heard of this, too? I read it on RetouchPro.com

Hi Joe, thank you for sharing this! I've never heard of the variations you've mentioned, but I am intrigued and will definitely check them out. My goal is always to simplify and speed up my workflow, so whatever is more time-consuming or complex to implement (considering the degree of improvement of the outcome) never sticks. But I am always eager to check new things out, so really thanks for the link and suggestions!

Though I'll happily concede there are exceptions to every rule, converting to 8-bit during the editing process is likely a false economy. On the other hand, if you're already working in a scenario where you have this option, you'll probably be aware of this... Just have to call it out as I'll always work in 16-bit+ if possible.

Of course, if your image size is too large for your machine to handle the fine-tuning with any reasonable speed, one can convert to 8-bit to dial-in values before reverting/undo to 16-bit and plugging in the values that you settled on.

I am not sure what exactly you mean, Stephan, all my sources are mentioned at the end of the article, and the screenshots are taken by me and Aleksey Dovgulya. Perhaps, you could share a link to what samples you are referring to.

I've been picking these points up on my own as I go along but it wasn't until reading this that all my suspicions about the different methods were true. Phlearn had a frequency separation demo the other day that did the apply-image technique and I actually inquired why that way over high-pass(which I was using previously)...this answered that clearly.

I also think points 3 and 4 are very relevant for the perfectionists out there. You can't retouch a face just one way or one tool. Well you can but if you really want it all very clean and tight you'll want to go through the trouble of different FS rounds for forehead vs checks vs neck, etc. Every image is different and every part of that image is different so different radii(sp) are used across the board.

Very true! I say it all the time - every image is unique, and being a problem solver with many tools under your sleeve is very beneficial. One tool, one way, one technique is a dead end approach in both photography and retouching!

This is not just timely as I am in the middle of a rough skin extravaganza... It is the best article on split frequency skin retouching that I have come across yet. I have been using Michael's method all morning with great success. I really like the control of blotchy color on the working layer. Works great for sculpting with light and dark tones found in the image as well.

So anyone know of any reason why no matter what image I use all I end up with when doing apply image is a flat gray layer, two versions of photoshop on two different computer, tried a dozen different files including some super sharp and some not so sharp.

an update on modified verification approaches for frequency lowering danielle glista marianne hawkins susan scollie hearing aids - adults 16932

an update on modified verification approaches for frequency lowering danielle glista marianne hawkins susan scollie hearing aids - adults 16932

Frequency lowering (FL) devices have been around for decades, offering signal processing designed to improve audibility of sounds for listeners with high-frequency hearing loss. Within the literature, several papers offer a review of the rationale and evidence on FL for managing high-frequency hearing loss (Alexander, 2013b; McCreery, Venediktoc, Coleman, & Leech, 2012; Simpson, 2009). In brief, listeners require access to a broad bandwidth of speech to detect and produce all phonemes. Access to the high-frequency components of speech in particular (e.g., the female /s/) can be limited via conventional hearing aid processing. When combined with an evidence-based fitting procedure, FL technology can help overcome device limitations and improve audibility for some listeners (Bohnert, Nyffeler, & Keilmann, 2010; Glista et al., 2009; Hopkins, Khanom, Dickinson, & Munro, 2014; Wolfe et al., 2010). Although the concept behind such technology has not changed, accessibility has. This relates to the fact that most manufacturers now offer some form of frequency lowering within the many devices available for clinical use. The provision of information to clinicians on how to fit and fine-tune frequency lowering devices is therefore an important topic. This article will focus on electroacoustic verification considerations for fitting frequency lowering hearing aids to children and adults in accordance with the American Academy of Audiology (AAA) guideline (AAA, 2013). The protocol presented includes specific stimuli and fitting steps designed to supplement the AAA fitting guideline (Scollie et al., 2016).

FL technology can be classified according to type of signal processing used; each having a unique effect on the aided signal (Alexander, 2013a, 2013b; McDermott, 2011; Mueller, Alexander, & Scollie, 2013; Scollie, 2013). FL devices apply digital signal processing to select a high-frequency region of the hearing aid input to be presented at a lower frequency in the output. Types of FL include frequency compression, transposition, translation and composition, for example. These different types can vary according to how the lowering is achieved (e.g., linearly versus nonlinearly) and whether an adaptive versus static amount of lowering is applied to the output signal (this can depend on the presence or absence of a high-frequency weighted input signal, for example). In addition, the hearing aid output for some FL processors includes both the original signal along with the frequency lowered signal; whereas some present an output signal that is narrower in bandwidth than the original input signal. Refer to Scollie et al. (2016) for a more detailed summary of the different types of FL.

The protocol presented in this paper considers FL as a means to provide access to high-frequency sounds, when these cannot be provided via conventional amplification. As hearing aid technology advances, it may be possible to amplify a broader frequency response without the use of FL. Some candidacy factors for the application of individualized FL settings include [adopted from the Ontario Infant Hearing Program: Protocol for the Provision of Amplification (IHP, 2014)]:

As with all hearing aid fittings, routine clinical verification is necessary to ensure that an appropriate amount of gain and output is provided across frequencies. This FL protocol recommends the use of a validated prescriptive formula as the starting point of all fittings. A few additional verification steps are recommended to ensure that an optimal amount of FL is provided. This can help ensure that each listener has access to important speech sounds needed when developing speech and language skills and for daily communication needs.

Current clinical guidelines recommend that the fitter maximize the output bandwidth available to the listener prior to activating FL through the use of validated prescriptive targets (AAA, 2013). The fitter can then determine the frequency at which the output of the hearing instrument falls below audibility for a given audiogram, or the MAOF: maximum audible output frequency (McCreery et al., 2014; McCreery, Brennan, Hoover, Kopun, & Stelmachowicz, 2013). In this protocol, we verify the hearing aid with a running speech signal, to determine the MAOF range. Specifically, the MAOF range spans from the point at which the long-term average speech spectrum (LTASS) crosses threshold to the point at which the peaks of speech cross threshold (Figure 1). This range can then be used as a target region in which to place the calibrated /s/ stimulus during verification and fine-tuning of FL (Scollie et al., 2016). A display of peak and valley measurements for the LTASS is needed when identifying the MAOF range.

The aim of this article is to discuss recommended stimuli, a step-by-step verification protocol, and optional measures to assist in the verification of hearing aid fittings with FL. A case example will be used to illustrate each step of the recommended protocol.

Previously recommended protocols have included two types of frequency-specific speech sounds: Live voice productions of /s/ and // and filtered speech with high-frequency bands of energy (Glista & Scollie, 2009). Live voice productions of speech sounds can be easily measured on the Audioscan Verifit system and allow for an estimation of audibility and approximation of bandwidth associated with each sound. With this information the fitter could estimate the sensation level and the approximate spectral separation between /s/ and //. However, there are limitations to using live voice production of speech sounds. These include the inability to present sounds at a calibrated/known level and the variability associated with repeated measurement due to gender and talker differences. Alternatively, filtered speech signals have been used within the Verifit system which present 1/3 octave bands of energy centered around 3150, 4000, 5000 and 6300 Hz. These have allowed the fitter to use a calibrated level during measurement that is repeatable. These filtered signals are limited in two important ways:

For the reasons discussed above, this article focuses on the use of pre-recorded, calibrated speech signals (/s/ and //) that, at the time of writing, have been implemented in the Audioscan Verifit2 system, and that can be downloaded for use with the Verifit1 or SL systems (http://www.dslio.com/?page_id=166). Note: the principles discussed in this article may also be applied to other verification systems. These signals were created by extracting phonemes from the International Speech Test Signal (Holube, Fredelake, Vlaming, & Kollmeier, 2010) and measuring each fricatives average spectrum. Synthetic fricatives were created that matched the observed spectra. These fricatives fall close to the peaks of speech and represent an average female production of the fricatives /s/ and // (Scollie et al., 2016). Some advantages of using these new stimuli include the ability to present them at a calibrated level and to estimate hearing aid output of fricatives using an accurate representation of fricatives. This allows for an accurate assessment of the spectral separation of /s/ and // for a given fitting. These signals do not account for variability between talkers, nor do they represent male speech. It is recommended that all digital noise reduction features be disabled when verifying with the calibrated /s/ and // signals to ensure accurate representation of the aided level.

The following clinical protocol is designed to assist fitters in the verification and fine-tuning of FL hearing aid fittings. A case example has been used in this section to illustrate the recommended fitting protocol. This example is of a 14 year old child, presenting with a sloping, high-frequency hearing loss. A behind-the-ear (BTE) hearing instrument has been fitted to this child using the DSL v5.0 prescription. Test box measures have been completed using an RECD value measured with insert phones coupled to a personal earmold (Moodie et al., 2016). Audiometric thresholds were measured using insert phones coupled to a personal earmold and have been entered into the Verifit2 software. Although only one type of FL has been used in the examples provided, the protocol is intended for use across all types of FL and has been electroacoustically validated with three different types of FL (Scollie et al., 2016).

Begin by verifying and fine-tuning the hearing aid to optimize the conventional hearing aid fitting. Ensure that the aided speech spectrum meets targets for the chosen fitting prescription and provides a broad bandwidth of audibility (Figure 2).

Figure 2. A screen capture of the aided verification results for a hearing instrument fitted to DSL v5.0 targets, without FL active. Measurements are displayed for the LTASS at soft (yellow curve), average (green curve) and loud (blue curve) presentation levels, as well as for the MPO (pink curve).

In addition to considering the candidacy factors stated above, this step lets you determine if electroacoustic verification suggests that FL may improve audibility of high-frequency sounds, when these cannot be made audible via conventional amplification. Start by measuring the aided response of the /s/ at 65 dB SPL, without FL and with all noise reduction features turned off (Figure 3). Determine if the /s/, including the upper shoulder, is audible and falls within the MAOF range for an LTASS measured at 65 dB SPL. If the measured /s/ falls outside of this range, proceed to step 3 to determine an appropriate FL setting.

Figure 3. The aided LTASS measured using a presentation level of 65 dB SPL (green). For this case, the /s/ does not fall within the MAOF range and is not audible. This fitting would be deemed a candidate for FL.

For listeners presenting with milder degrees of hearing loss, it may be possible to measure an audible /s/ within the MAOF range without enabling FL. This relates to recent technological advancements resulting in improved high-frequency gain and audible bandwidth via conventional hearing aids. This highlights the need to assess candidacy on a case-by-case basis when FL is first being considered, and to reassess candidacy when providing a new hearing aid fitting. Refer to Scollie et al. (2013) for a case example of a borderline candidate for FL (Scollie, Glista, & Richert, 2013). For this case, outcome measures were used to help determine FL candidacy, together with electroacoustic measurements, while factoring in the candidacy factors discussed above.

Start by enabling the default FL setting in the hearing instrument. Measure the aided response for /s/ to determine if the upper shoulder is audible and within the MAOF range of the LTASS presented at 65 dB SPL. Fine-tune the strength of the FL setting until the /s/ is audible and falls within the MAOF range using the weakest possible setting (Figure 4); this setting will likely be associated with the best possible sound quality when considering stronger FL settings in comparison (Parsa, Scollie, Glista, & Seelisch, 2013; Souza, Arehart, Kates, Croghan, & Gehani, 2013). Note: the fitter can leave the /s/ stimulus running when exploring different settings. It is recommended that the fitter choose a setting that allows the upper shoulder of /s/ to reside close to the upper limit of the MAOF range. For hearing losses of greater severity, it may not be possible to achieve full audibility of /s/, especially if the maximum FL setting has been reached.

Figure 4. Both screen captures display the aided LTASS measured using a presentation level of 65 dB SPL (green). The LEFT screen capture displays the /s/ (pink) after fine-tuning the FL setting. The /s/ has been made audible and the upper shoulder falls within the MAOF range. The RIGHT screen capture depicts a setting that was considered too strong (blue /s/), the fine-tuned setting (pink /s/) and a setting that was considered too weak (yellow /s/).

Provision of counselling to caregivers and therapists may be important in the event that they are performing listening checks on fittings employing FL, for example. This is because the sound quality of FL fittings may differ from that of conventional hearing aid fittings; this will depend on the hearing loss of the listener and the strength and type of the FL setting used in the fitting (Parsa et al., 2013; Souza et al., 2013). The fitter may choose to alert the person performing the listening check of possible sound quality differences due to the nature of FL technology. As always, it is important to incorporate feedback into follow-up appointments; this may come in the form of feedback from the listener (adults and older children) or from therapists of children enrolled in a program of oral language development. For example, if the listener cannot functionally detect /s/, it may be the case that the fitting needs to be adjusted to provide more gain or output and/or the FL setting may need to be strengthened. Feedback related to /s-/ discrimination difficulty is discussed below.

It is possible to make descriptive measures of /s-/ separation to help with counselling or troubleshooting around feedback concerning lisping or slushy sound quality, or difficulty with /s-/ discrimination. In such cases, it may be that too much FL has been applied to a given fitting. To explore this further, it is recommended that the fitter electroacoustically evaluate /s-/ separation. Start by taking measurements of the /s/ and // for the chosen FL setting and compare the measured responses (Figure 5). In the case where the fine-tuning steps outlined above have been followed, it is likely that the separation between /s/ and // is already maximized. This is because the protocol recommends using the weakest possible FL setting, while maintaining audibility of /s/. In the case where the fitter has fine-tuned to include a stronger FL setting based on user preference, for example, greater /s-/ overlap can occur (Figure 6). In an example such as this one, it may be possible to provide a weaker setting with greater /s-/ separation.

This fitting protocol illustrates a method for providing full audibility of /s/. In some cases, the fitter may decide to provide a weaker FL setting (other than what would be recommended by this protocol) in the case where the sound quality associated with a FL fitting is unacceptable to the listener, for example. This may result in reduced audibility of high-frequency phonemes (refer to Figure 4); this compromise between audibility and sound quality can be assessed through the use of the optional measures discussed above, combined with a listening check and feedback from the hearing aid wearer. Consideration should also be given to the idea that some listeners require time to acclimatize to FL fittings in order to achieve maximal benefit (Glista, Scollie, & Sulkers, 2012; Wolfe et al., 2011). Further research is needed to determine if acclimatization time relates to perceived sound quality of FL fittings.

Figure 5. A screen capture of the aided response of /s/ (pink) and // (blue) for a presentation level of 65 dB SPL for the fine-tuned FL setting. The spectrum of /s/ and // are separated in terms of peak levels and in frequency locations at the lower shoulders.

Figure 6. A screen capture of the aided response of /s/ (pink) and // (blue) for a stronger FL setting. The spectrum of /s/ and // for this setting appear more similar in terms of bandwidth and there is less separation of frequency location of the lower shoulder of /s/ versus //, compared to the fitting shown in Figure 5.

This article provides an update on electroacoustic verification considerations for fitting FL hearing aids to children and adults in accordance with the AAA guideline (AAA, 2013). Candidacy factors, verification stimuli and fitting steps are recommended to assist fitters in choosing appropriate FL settings. The overall goal of the outlined protocol is to provide FL fittings employing the weakest possible setting, while improving audibility of high-frequency sounds, in comparison to the conventional setting. Here is a summary of the steps that have been discussed in the article:

Pre-recorded and calibrated stimuli available for use with hearing aid test systems such as the Audioscan Verifit and are suitable in determining candidacy for FL technology. The stimuli discussed in this article (calibrated /s/ and //) have been developed and evaluated for use in hearing aid verification using clinically available equipment for fine-tuning of FL technology (Scollie et al., 2016). The fitting protocol presented in this article can provide guidance when deciding whether to activate FL and when judging whether the overall strength of a setting is appropriate.

American Academy of Audiology. (2013). American Academy of Audiology clinical practice guidelines: Pediatric amplification. Retrieved from http://audiology-web.s3.amazonaws.com/migrated/PediatricAmplificationGuidelines.pdf_539975b3e7e9f1.74471798.pdf

Glista, D., Scollie, S., Bagatto, M., Seewald, R., Parsa, V., & Johnson, A. (2009). Evaluation of nonlinear frequency compression: Clinical outcomes. International Journal of Audiology, 48(9), 632-644.

Glista, D., Scollie, S., & Sulkers, J. (2012). Perceptual acclimatization post nonlinear frequency compression hearing aid fitting in older children. Journal of Speech, Language, and Hearing Research, advanced online publication.

Hopkins, K., Khanom, M., Dickinson, A.M., & Munro, K.J. (2014). Benefit from non-linear frequency compression hearing aids in a clinical setting: The effects of duration of experience and severity of high-frequency hearing loss. International Journal of Audiology, 53, 219-228.

IHP (Ontario Infant Hearing Program). (2014). Ontario Infant Hearing Program: Protocol for the provision of amplification. Retrieved from http://www.mountsinai.on.ca/care/infant-hearing-program/documents/ihp_amplification-protocol_nov_2014_final-aoda.pdf

McCreery, R.W., Alexander, J., Brennan, M.A., Hoover, B., Kopun, J., & Stelmachowicz, P.G. (2014). The influence of audibility on speech recognition with nonlinear frequency compression for children and adults with hearing loss. Ear and Hearing, 35(4), 440-447.

McCreery, R.W., Brennan, M.A., Hoover, B., Kopun, J., & Stelmachowicz, P.G. (2013). Maximizing audibility and speech recognition with nonlinear frequency compression by estimating audible bandwidth. Ear and Hearing, 34(2), e24-e27.

McCreery, R.W., Venediktoc, R.A., Coleman, J.J., & Leech, H.M. (2012). An evidence-based systematic review of frequency lowering in hearing aids foschool-age children with hearing loss. American Journal of Audiology, 21, 313-328.

Moodie, S., Pietrobon, J., Rall, E., Lindley, G., Eiten, L., Gordey, D., . . . Scollie, S. (2016). Using the real-ear-to-coupler difference within the American Academy of Audiology pediatric amplification guideline: Protocols for applying and predicting earmold RECDs. Journal of the American Academy of Audiology, 27(3), 264-275.

Scollie, S., Glista, D., & Richert, F. (2013, December). Frequency lowering hearing aids: Procedures for assessing candidacy and fine tuning. Paper presented at the A Sound Foundation Through Early Amplification conference. Chicago, Illinois.

Scollie, S., Glista, D., Seto, J., Dunn, A., Schuett, B., Hawkins, M., . . . Parsa, V. (2016). Fitting frequency-lowering signal processing applying the AAA pediatric amplification guideline: Updates and protocols. Journal of the American Academy of Audiology, 27(3), 219-236.

Wolfe, J., John, A., Schafer, E., Nyffeler, M., Boretzki, M., & Caraway, T. (2010). Evaluation of non-linear frequency compression for school-age children with moderate to moderately-severe hearing loss. Journal of the American Academy of Audiology, 21(10), 618-628.

Wolfe, J., John, A., Schafer, E., Nyffeler, M., Boretzki, M., Caraway, T., & Hudson, M. (2011). Long-term effects of non-linear frequency compression for children with moderate hearing loss. International Journal of Audiology, 50(6), 396-404.

Glista, D., Hawkins, M., & Scollie, S. (2016, April). An update on modified verification approaches for frequency lowering devices.AudiologyOnline, Article 16932. Retrieved from www.audiologyonline.com

Dr. Susan Scollie is an Associate Professor at the National Centre for Audiology, University of Western Ontario. With colleagues, she developed version 5.0 of the DSL method for hearing aid fitting. Her current research focuses on frequency compression signal processing, and outcomes of hearing aids for infants, children and adults.

Dr. Susan Scollie is an Associate Professor at the National Centre for Audiology, University of Western Ontario. With colleagues, she developed version 5.0 of the DSL method for hearing aid fitting. Her current research focuses on frequency compression signal processing, and outcomes of hearing aids for infants, children and adults.

fathom mono, free synth plugin, download fathom mono plugin, free

fathom mono, free synth plugin, download fathom mono plugin, free

Many synthesizers are advertised as alias free. If you place a spectrum analyzer on the plugin track it reveals a frequency profile which gradually tapers off into the upper frequencies, proof that your synth is using raw waveforms and internally filtering the oscillator.

Shown above is the Fathom saw tooth at 128 partials in the frequency domain. This unedited screen capture shows a high frequency noise floor well below -130 dB in relation to the amplitude, or less than one part in one million. Notice that there is no aliasing, imaging or artifacts after the last partial.

We achieve this taking your edited waveform, running it through an FFT (Fast Fourier Transform) to derive the component partials, and then storing the result accurately in a buffer of 16384 samples for each oscillator single cycle. Then at run time the oscillator fetches samples from this buffer for any varying detune frequency using nonlinear interpolation between buffer points.

Clicking results from starting a waveform in mid-cycle which creates an abrupt change in amplitude from one sample to the next. Many software synths have the clicking problem because they do not take steps to avoid it. Clicking also happens when any modulation which effects the waveform passes through the vertical edge of an envelope while the oscillator is in mid-cycle.

Even with oscillator voices detuned, the processor keeps track of the relative phase of each oscillator, and at the start of each note plays each oscillator virtually with no volume for a few microseconds until the beginning of its waveform. In this way all voices maintain their relative phase but never start in the middle of a waveform.

Shown above is a screen capture of a Fathom note transition with a single oscillator sin wave and detune set to one voice in free running mode. If a sequencer note stops and a new one starts at the same point in the host sequence, Fathom will make the frequency transition in mid-cycle, emulating a single oscillator hardware synth, even when running in polyphonic mode.

Above is a Fathom note transition, single oscillator sin wave, with detune set to eight voices in retrigger mode. All voices finish their cycle in the terminating note and start at the beginning of their cycle in the new note.

Any references to any brands on this site/page, including reference to brands and instruments, are provided for description purposes only. For example references to instrument brands are provided to describe the sound of the instrument and/or the instrument used in the sample. Plugin Boutique do not have (nor do they claim) any association with or endorsement by these brands. Any goodwill attached to those brands rest with the brand owner. Plugin Boutique or its Suppliers do not accept any liability in relation to the content of the product or the accuracy of the description. "RHODES" is a registered trademark of Joseph A Brandstetter.

mev screener - midwestern industries, inc

mev screener - midwestern industries, inc

The high-frequency screens manufactured by Midwestern can be utilized in many screening applications from rugged quarry and rock sizing to sand and gravel processing and high volume fine mesh screening. With a variety of sizes and screening decks, the versatile MEV Screener can fit numerous applications.

The MEV High-Frequency Screener is a rectangular screener that utilizes an elliptical motion to convey material across itsscreening surface. Available in sizes three-foot by five-foot (3 x 5), four-foot by eight-foot (4 x 8), and five-foot by ten-foot (5 x 10) with the availability of one to five screening decks gives the MEV Screener the versatility to meet your screening needs.

The MEV Screener is designed to retain material at the feed end for a longer period of time and then gently slops the material near the discharge end, assisting itoff the screening deck and into production. This is achieved by the screeners unique parallel-arc configuration. Crossbars support the end-tensioned screens tocreate a flat screening surface, thus maximizing the screening area.

The end-tensioned screens used in the high-frequency screener simplify changing screen panels. End-tensioning permits the use of square-opening and slotted screens and is accurately maintained by a spring-loaded drawbar. Users can make screen changes in 1015 minutes.

Midwesterns commitment to providing our customers with outstanding screening products continues with our full line of replacement rectangular screens. Our screens are manufactured to fit all makes and models of screeners.

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