Re: Testing whether some humans can hear high frequencies inaudible to "normal" humans

[Bob Masta <audio@xxxxxxxxxxx>]

Might not need an external card, since most recent systems
(even cheap laptops) can sample at 96 kHz or higher. 
However, you do need to verify that the output filters are
actually passing frequencies above 22 kHz... some don't. 

Just as important is whether you have headphones or 
speakers that can reproduce the higher frequencies... most
don't, or if they do their response is full of dips and
peaks in the upper frequencies.  (Even "perfect" flat-
response systems will exhibit dips and peaks due to standing
waves in the ear canal or room, etc.)

But as a first effort, you should just try your normal
headphones and default sound card.  After all, the child
doesn't need to be able to hear above 20 kHz to hear sounds
his parents can't hear.

You can use my Daqarta software to generate the test tones
in real time.  Since the question is about a startle
response, you may want to have randomized presentation.  You
can do that manually if you have a "blind" test situation
where the child can't see you.   Daqarta can be set up to do
the randomized presentation, but it doesn't have a neat way
(yet) to collect responses and associate them with each
presentation, so you know which frequencies he heard.

Daqarta has a 30-session/30-day free trial period, but in
this case (signal generation only) there are no limits,
since after the trial only the inputs are disabled.  So it
becomes a free signal generator... enjoy!

Best regards,

Bob Masta


------------------------


On 14 Jun 2010 at 11:09, Peter Lennox wrote:

> You'd need an external sound card, of reasonable quality, as the internal cards on PCs don't go above 20KHz - you need to go up to 26KHz, so need to play 96 KHz sample rate .wavs
> Regards
> ppl
> 
> ________________________________
> From: AUDITORY - Research in Auditory Perception [mailto:AUDITORY@xxxxxxxxxxxxxxx] On Behalf Of Divakaran, Ajay
> Sent: 14 June 2010 01:25
> To: AUDITORY@xxxxxxxxxxxxxxx
> Subject: Testing whether some humans can hear high frequencies inaudible to "normal" humans
> 
> Dear List,
> 
> My friend thinks that his child can hear frequencies that are inaudible to other humans because of which he sometimes reacts with alarm that no one else understands. Is there a way we can verify this systematically? In my electronics lab during my undergrad one of my friends tested my hearing by varying the frequency output of a signal generator. Is there  a possibility of doing that on a PC?
> 
> Also, I would highly appreciate any references on music therapy for language delayed children. I am interested in vocal music training in particular but would appreciate any general music training as well for therapeutic purposes.
> 
> Best Regards,
> ajay
Bob Masta
 
            D A Q A R T A
Data AcQuisition And Real-Time Analysis
           www.daqarta.com
Scope, Spectrum, Spectrogram, Signal Generator
    Science with your sound card!