more on recorders

Thu Sep 9 22:39:29 UTC 2004

---------- Forwarded message ----------
Date: 9 Sep 2004 17:01:01 -0000
From: lexicographylist at yahoogroups.com
To: lexicographylist at yahoogroups.com
Subject: [Lexicog]  Digest Number 197

Topics in this digest:
......
      2. Audio devices suitable for language data collection
           From: "Norbert Rennert" <norbert.rennert at sil.org>
      3. Re: Audio devices suitable for language data collection
           From: Mike Maxwell <maxwell at ldc.upenn.edu>
      4. Re: Audio devices suitable for language data collection
           From: Susan Gehr <vurayav at hotmail.com>
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Message: 2
   Date: Thu, 9 Sep 2004 09:00:26 -0700
   From: "Norbert Rennert" <norbert.rennert at sil.org>
Subject: Audio devices suitable for language data collection

Hello All,

I'm looking at purchasing an mp3 recorder which can serve as a field
language data collection device. I have the following minimum requirements:

- bit rate recording must be over 128 kbs
- have an external microphone jack in addition to built-in mic
- be able to play back a user-defined segment in a loop
- preferably usb 2.0 transfer mode

So far in my research I have found that the IRiver MP3 Flash players fulfill
these requirements. My questions are:
- Does anyone have any experience with these players or others and can say
if the quality of the recording is good enough to do phonetic analysis?
- I have heard that the mp3 format truncates the higher frequencies. Does
this affect the sounds produced by human speech?
- What is the minimal bit rate you should record at to be able to use the
recording for phonetic analysis?
- is the built-in microphone usable for collecting language data? At what
distance should the microphone be from the speaker to obtain an optimal
recording?

Any feedback from experienced users is greatly appreciated.

Norbert Rennert
Canada Institute of Linguistics

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Message: 3
   Date: Thu, 09 Sep 2004 12:10:35 -0400
   From: Mike Maxwell <maxwell at ldc.upenn.edu>
Subject: Re: Audio devices suitable for language data collection

Norbert Rennert wrote:

> Hello All,
>
> I'm looking at purchasing an mp3 recorder which can serve as a field
> language data collection device. ...
 > My questions are:
> - Does anyone have any experience with these players or others and can say
> if the quality of the recording is good enough to do phonetic analysis?
> - I have heard that the mp3 format truncates the higher frequencies. Does
> this affect the sounds produced by human speech?

Have a look at http://www.emeld.org/school/classroom/audio/,
particularly the chart at the bottom.  They recommend against MP3 for
phonetic analysis because of the data loss.  (It's presumably fine if
you're just doing orthographic transcription of a language you know.)

	Mike Maxwell
	Linguistic Data Consortium

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Message: 4
   Date: Thu, 09 Sep 2004 09:43:31 -0700
   From: Susan Gehr <vurayav at hotmail.com>
Subject: Re: Audio devices suitable for language data collection

I'm working on my MA in linguistics and I'm also working for the Karuk Tribe
to document and revitalize the language. I've just been working on buying
some more equipment myself so that we can check it out to other folks
working on the language. They aren't going to be doing acoustic analysis, so
I was thinking about going the cheaper route of minidisc recorders, but the
amount of work it takes to get the files onto the computer in a wav format
has made me decide to buy another compact-flash card based recorder.

I think I'd even have them work with analog cassette recorders before I'd
hassle with mp3 or minidisc recorders, but I think I'm just reacting to the
compression that mp3 and minidisc recorders introduce.

Here are some links to some articles that have helped me:

Workshop on Acoustic Voice Analysis:  Summary Statement
(see especially pp. 28-30 for recommendations on equipment and file formats)
http://www.ncvs.org/ncvs/info/rescol/sumstat/sumstat.pdf

"Field Recording Equipment" from Linguist List
http://www.linguistlist.org/issues/14/14-720.html

And because your question made me look at that article again, I found this
gem:

<http://bartus.org/contents/index.php?module=ContentExpress&func=display&cei
d=14&bid=20&btitle=Audio%20Technology&meid=19>

Also, I've worked on a project that involved acoustic analysis, and the
quality of mp3 recorders and even minidisc recorders are not good enough to
do phonetic analysis.  I was told that they introduce inaccuracies into your
pitch measurements, rendering the measurements unusable.

I recorded everything on DAT recorders for that project, and now I use a
Compact Flash card based recorder which records in a WAV format.  I'm
recoring at a bit rate of 1536kbps. I don't know for sure if that is
overkill or not, but it's the only rate at which I can get my computer to
read the files created by the recorder.

If you're collecting language data for the purposes of acoustic analysis,
then I highly doubt the built in microphone will be sufficient.

>From the "Workshop on Acoustic Voice Analysis:  Summary Statement"

"a. A professional-grade condenser microphone (omnidirectional or cardioid)
with a minimumsensitivity of -60 dB should be used (Titze & Winholtz, 1993).
b. For steady vowel utterances, the mouth-to-microphone distance can be held
constant and less than 10 cm (preferably 3-4 cm) in order to avoid an
artificial wow and to maintain a high signalto-noise ratio; a miniature
head-mounted microphone is recommended (Winholtz & Titze, in press).
This recommendation does not necessarily apply to general speech analysis,
where breath noises can contaminate the signal at close distances."

Hope that helps.
--
Susan Gehr
Karuk Language Program Director
Karuk Tribe of California
(530) 493-5305 x2205
sgehr at karuk.us

Karuk Language Resources on the Web - http://www.karuk.org/

On 9/9/04 9:00 AM, "Norbert Rennert" <norbert.rennert at sil.org> wrote:

> Hello All,
>
> I'm looking at purchasing an mp3 recorder which can serve as a field
> language data collection device. I have the following minimum requirements:
>
> - bit rate recording must be over 128 kbs
> - have an external microphone jack in addition to built-in mic
> - be able to play back a user-defined segment in a loop
> - preferably usb 2.0 transfer mode
>
> So far in my research I have found that the IRiver MP3 Flash players fulfill
> these requirements. My questions are:
> - Does anyone have any experience with these players or others and can say
> if the quality of the recording is good enough to do phonetic analysis?
> - I have heard that the mp3 format truncates the higher frequencies. Does
> this affect the sounds produced by human speech?
> - What is the minimal bit rate you should record at to be able to use the
> recording for phonetic analysis?
> - is the built-in microphone usable for collecting language data? At what
> distance should the microphone be from the speaker to obtain an optimal
> recording?
>
> Any feedback from experienced users is greatly appreciated.
>
> Norbert Rennert
> Canada Institute of Linguistics
>

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