audio recorders

[George D. Allen]

Brian, et al.,

When making audio recordings of infants' and children's vocalizations, it
helps to know whether your recordings are intended to be analyzed
auditorily or instrumentally (or both).  If you are going to do
instrumental analysis, then it matters what microphone you use, since many
have significant drop-outs in the frequency range of interest.  Whatever
you are going to use, be sure to calibrate it soon after you obtain it, to
be on the safe side.

And *always* record in stereo.  If you are going to analyze by ear, the
stereo (cocktail party) effect is worth approximately 30 dB of
signal-to-noise ratio.  It matters less where your two mikes are placed, as
long as they're not too close together, since what your ears need is simply
two separate sources of the same signal.  I always have one mike close to
the child and one farther away, with their inputs set to about the same
recording level.  That way, when the child vocalizes softly, the close one
gets a good signal for later analysis, yet when he or she yells,
overloading the close one, the far one gets a good signal.  And you can
always adjust the listening mix by using the balance control on output.

These and other suggestions are in my 1983 paper, "Some tips on tape
recording speech/language samples,"  J Natl Student Sp Lang Hg Assn, Vol
11, No 1, December, 1983, pp 10-17.

Good luck with your recordings.


George D. Allen <alleng at msu.edu>
Michigan State University College of Nursing
A230 Life Sciences Bldg., E Lansing, MI 48824-1317
Voice: (517) 353-5976; Fax: (517) 353-9553

"Life is what happens while you're making other plans."
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