Expanding a little on what John said about transitioning between devices, having the source material in an uncompressed or low-compression file will make it easier if there is conversion that needs to happen in the future. Every time you convert an audio file into a different format or sample rate you're going to lose some quality, but going from high-quality to lower-quality is a lot easier than the other direction.

On a related note, if you do have messages already recorded in a different format than WAV, converting them all to WAV files before adding them to a device just because it's a better long-term format isn't a good idea, since any conversion will affect sound quality. It's best to keep the originals, whatever they are, and if you need to convert them for a specific device, do it but keep the originals for converting to the next device. There are enough robust audio/video conversion tools out there now that a technical individual should be able to help you convert to whatever format your device will accept.

-Brian Whitmer
Founder, CoughDrop

On Thu, May 25, 2017 at 2:03 PM, Hurtig, Richard R <xxxxxx@uiowa.edu> wrote:
I want to reinforce John Costello’s comments. It is best to use the least compression. The key is to sample at a sufficiently high frequency and to not use a low bit converter. The reason for needing the higher bit rate is to get a greater dynamic range. In the past when storage was a problem,  low bit rates and compression were needed to allow collecting many samples. However today’s technology, with large and cheap memory has made it possible to collect a large sample without sacrificing the resolution needed.
 
Richard Hurtig, Ph.D.
ASHA Fellow
Professor Emeritus
Department of Communication Sciences & Disorders
The University of Iowa




On May 25, 2017, at 3:52 PM, McCaffrey, Julia <xxxxxx@cshs.org> wrote:

Thank you, John.  This info is extremely helpful. :) 
 
Julia McCaffrey, MS, CCC-SLP
Speech Language Pathologist III
Cedars Sinai ALS Clinic
 
 
From: xxxxxx@alsa.simplelists.com[mailto:xxxxxx@alsa.simplelists.com] On Behalf Of Costello, John (Otolaryngology)
Sent: Thursday, May 25, 2017 12:49 PM
To: xxxxxx@alsa.simplelists.com
Subject: Re: [External] Re: best audio file format for message banking
 
 
Hi Julia, 
 
I have run in to trouble incorporating AAC, AIFF, WMA, M4A and FLAC formats.    There are others I have not tried as we really have stuck to .wav without any difficulty.     The troubles I ran into were related to them being not  accepted in some SGDs or being imported into itunes for storage OR use with an app such as Predictable (although they are now moving away from itunes storage and import of audio files).
 
BTW, the other consideration it the baud rate.    I have not exhausted all options BUT I can tell you that every baud rate ACCEPT for 44/16 has given me some kind of trouble at least once.
 
On a related note, someone with whom I did not work called me to tell me they could not upload their banked message files to our beta Messagebanking tool housed at MyTobiiDDynavox.    Turns out they were using a baud rate lower than 44/16 and the system would not recognize it.    I’ve not fully explored all the potential options and successes/problems there yet but I figured I would pass that hiccup along since I’ve learned it.
 
Best,
John
 
 
John M. Costello
Director, Augmentative Communication Program and 
ALS Augmentative Communication Program
Boston Children's Hospital
                                   @costello_j
 
 
 
 
 
 
From: <xxxxxx@alsa.simplelists.com> on behalf of "McCaffrey, Julia" <xxxxxx@cshs.org>
Reply-To: "xxxxxx@alsa.simplelists.com" <xxxxxx@alsa.simplelists.com>
Date: Thursday, May 25, 2017 at 3:35 PM
To: "xxxxxx@alsa.simplelists.com" <xxxxxx@alsa.simplelists.com>
Subject: RE: [External] Re: best audio file format for message banking
 
Awesome.  Huge thanks for the quick reply,  John.  I will share this info with my message banking clients!
 
One quick follow up question – do you know if there are specific audio file formats that clients should always AVOID using when message banking?  For example, audio file formats that you have found to be extremely difficult to use later with an SGD?  My challenge is some individuals have started recordings long before they met me, and they have used all sorts of different recording tools and formats…
 
Julia McCaffrey, MS, CCC-SLP
Speech Language Pathologist III
Cedars Sinai ALS Clinic
 
 
 
 
From: xxxxxx@alsa.simplelists.com[mailto:xxxxxx@alsa.simplelists.com] On Behalf Of Costello, John (Otolaryngology)
Sent: Thursday, May 25, 2017 12:28 PM
To: xxxxxx@alsa.simplelists.com
Subject: [External] Re: best audio file format for message banking
 
From the time we started Message Banking, we have wanted the highest quality recording.  The reasons are numerous including:
 
  1.  If done proactively, the end technology (should the messages be needed) has not been identified.   Given, in our experience some people have message banked over years before their messages are used, we want to be cautious and be sure the recording format used fits the technology of the future.
  2. If tech of the future requires high quality recordings, .wav will fit the bill.  You can make .wav a lower quality but making a lower quality into a .wav (by changing the tag) does not really increase the quality 
  3. We now have several people who are incorporating their banked messages in to their second or third technology where by a current SGD has been used for four years and now a new SGD is acquired.    We’ve been able to incorporate the banked messages from seven years ago into each technology without trouble.
  4. Some recording qualities cannot be incorporated into certain technologies.   The .wav format gives you maximum flexibility and will not require a technology identified at the time of need by a good clinical feature match to be eliminated because it will not accommodate the banked file format.
  5. With the now hundreds of people who have message banked hundreds or even several thousand messages each through our program over more than a decade, we have had no difficulty merging the .wav files into the tech of choice.  Depending on the SGD it has sometimes been more labor intensive than others.   Fortunately there is a growing trend with developers/manufacturers to support auto population.
 
 
Best,
John
 
John M. Costello
Director, Augmentative Communication Program and 
ALS Augmentative Communication Program
Boston Children's Hospital
                                   @costello_j
 
 
From: <xxxxxx@alsa.simplelists.com> on behalf of "McCaffrey, Julia" <xxxxxx@cshs.org>
Reply-To: "xxxxxx@alsa.simplelists.com" <xxxxxx@alsa.simplelists.com>
Date: Thursday, May 25, 2017 at 3:12 PM
To: "xxxxxx@alsa.simplelists.com" <xxxxxx@alsa.simplelists.com>
Subject: best audio file format for message banking
 
Is it still true that .WAV files are the best audio format to use when completing message banking?  If so, why?  Clients often ask me this, and I generally answer that it has to do with compression and sound quality recorded in a WAV file (less compressed/better quality) versus MP3 or MP4 (more compressed/poorer quality).
 
I recognize that a sound engineer may be able to hear the difference between a WAV and MP3/MP4 recording, but is it a difference that truly matters for SGD speech output intelligibility? 
 
Thanks in advance.  
 
Julia McCaffrey, MS, CCC-SLP
Speech Language Pathologist III
Cedars Sinai ALS Clinic
 
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