J wrote:
>
> At the listed frequencies of around 11-13 kHz, you may have trouble finding
> good speakers or headphones to reproduce those frequencies. bottom of the
> line speakers or headphones may not generate as much sould as you're
> thinking. Also there's some frequency roll off about 1kHz that naturally
> attenuates sound. There are ear shape related 'holes' that naturally occur,
> but I'm not sure if they exist in that frequency range and I don't have the
> documentation handy to check :/ . If your frequency is in one of them, you
> might have better luck with headphones than speakers.
>

When I was involved in hearing research we used to buy transducers from
this company: <http://www.knowleselectronics.com/>. The transducers are
designed to fit to a small flexible tube which can be mounted in the ear
canal in various different ways. I know that at frequencies above 10 kHz
it can get very tricky trying to accurately control the absolute SPL
that is delivered to the ear canal - small movements of the transducer
tube etc have a big effect. You also have to drive the transducers
pretty hard at the high frequencies to get a reasonable SPL.

You might also want to take a look at the various transducers etc from
Etymotic: <http://www.etymotic.com/>.

If you want to try headphones initially then Sennheiser heaphones tend
to be popular for hearing research and you should be able to find
calibration data on the WWW for various models.
<http://www.sennheiserusa.com/>

Paul