Date: Fri, 7 Oct 2011 11:50:34 -

Author: Steve Anderson

Subject: Re: Got a Frequency Range of Hearing Experiment?

Post:

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> All I heard were some short beeps, then there was silence, but =
perhaps it was not my hearing =96 perhaps the higher-frequency beeps did =
not exist!

those sounds do not exist for me, either (age 55).
however, the students detect those frequencies.=20
they shriek if the freq. sweep is too loud (cause I can't hear it, so, I =
turn it up)

Some claim to hear the dog-deterrent whistles and one, even complained =
about motion sensors (24-28 khz)
and, of course, there is the famous mosquito ringtone (your computer =
speakers may vary)
http://www.freemosquitoringtones.org/hearing_test/


> -Many thanks for any ideas, suggestions and experience sharing.
> -Do you think that ordinary amplifiers, generators, speakers, =
headphones and microphones would work?


work, sure, how linearly? we just do it as a demo using
a powered Bose speaker system, that is pretty flat, (using spectrum =
analyzer with built-in)
a Tektronix 3021 ARB with a 20 second log sweep 20-20khz
(so there is enough time during sweep, to get the low frequencies)

of course, each combination of amps, generators, and speakers, will have =
different spectral levels or dips.
the conventional wisdom is, invest in the speakers.

for below-low (2-20 Hz), I put a "mustache" of slits, cut into a post-it =
note,
in front of the sub bass port. This looks humorous and flaps with the =
"breeze".
The Pasco function generator (9527?) has enough to visibly drive a cone =
at 1 Hz.

if you have an i-something, try the "Audio Kit" app
http://store.sinusoid.com/software/iphone-apps/aklite.html
I really enjoy this one... Thanks Steve!


--Apple-Mail-86-403818613
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Content-Type: text/html; charset="windows-1252"

All I heard were some short beeps, then there was silence, =
but perhaps it was not my hearing =96 perhaps the higher-frequency beeps =
did not =
exist!those =
sounds do not exist for me, either (age 55).however, the =
students detect those frequencies. they shriek if the =
freq. sweep is too loud (cause I can't hear it, so, I turn it =
up)Some claim to hear the dog-deterrent =
whistles and one, even complained about motion sensors (24-28 =
khz)and, of course, there is the famous mosquito ringtone =
(your computer speakers may vary)http://www.fre=
emosquitoringtones.org/hearing_test/-Do you think that ordinary amplifiers, generators, speakers, =
headphones and microphones would =
work? =
;work, sure, how linearly? we just do it as a demo usinga =
powered Bose speaker system, that is pretty flat, (using spectrum =
analyzer with built-in)a Tektronix 3021 ARB with a 20 second =
log sweep 20-20khz(so there is enough time during sweep, to =
get the low frequencies)of course, each =
combination of amps, generators, and speakers, will have different =
spectral levels or dips.the conventional wisdom is, invest in =
the speakers.for below-low (2-20 Hz), I put a "mustache" =
of slits, cut into a post-it note,in front of the sub bass =
port. This looks humorous and flaps with the "breeze".The =
Pasco function generator (9527?) has enough to visibly drive a cone at 1 =
Hz. if you have an =
i-something, try the "Audio Kit" apphttp:/=
/store.sinusoid.com/software/iphone-apps/aklite.htmlI =
really enjoy this one... Thanks =
Steve!=

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