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Re: question on infrasound recordings

Subject: Re: question on infrasound recordings
From: "Eric Benjamin" ericbenjamin2
Date: Fri Jun 30, 2006 12:23 pm (PDT)
There is a common misapprehension that human hearing
simply stops at 20 Hz.  While this is true for hearing
at high frequencies, hearing at low frequencies simply
becomes progressively less acute.  20 Hz is an
extremely arbitrary low-end cut-off.  A typical
threshold value for a young adult at 20 kHz is in the
range of 100 dB SPL, but it is extremely variable from
individual to individual.  Applying the same criterion
of 100 dB SPL threshold on the low end would yield a
lower cutoff of about 12 Hz, and this is much less
variable from individual to individual.  And this is
just for the hearing aspect of sensation; not
including body sensation.

The best reference on this subject of which I am aware
"Thresholds of audibility for very low-frequency pure
tones", N.S. Yeowart, M. Evans, Journal of the
Acoustical Society of America, April 1974 -- Volume
55, Issue 4, pp. 814-818

This paper presents new binaural-hearing-threshold
data obtained (a) by an earphone method over the
frequency range 5=96100 Hz and (b) by a whole body
chamber method over the range 2=9620 Hz. The results
obtained are in excellent agreement with recent
reported data. The binaural to monaural listening
advantage appears to remain at 3 dB throughout the
frequency range. A good approximation to the binaural
threshold of hearing may be formed by lines from the
point 92.0 dB SPL at 15.5 Hz with slopes of 12.3
dB/octave for frequencies below 15.5 Hz and 22.2
dB/octave above.

--- Mike Feldman <> wrote:

> ilse van opzeeland wrote:
> > For a soundscape project I would like to do some
> first
> > pilot infrasound recordings of the city. ...
> How are you going to present the recordings?
> Infrasound
> is air pressure variations too low to hear.  Are you
> going
> to speedup the sound on playback, or just have some
> visual
> representation?
> -- Mike -- who likes to watch the sub cones move in
> and out

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