Subject: Re: High frequency hearing From: Bob Masta <masta(at)UMICH.EDU> Date: Wed, 6 Nov 2002 08:28:11 -0500One reason for the paucity of data on high frequency hearing may be the difficulty of obtaining reliable and meaningful values. As the frequency gets higher, it's harder and harder to find a transducer with a flat response, and even if you do, the overall system response may be far from flat due to standing waves in the ear canal, etc. In anesthetized animals, you can place a small probe tube very near the typanum to measure the actual sound delivered, but at high frequencies even a slight position change may lead to big differences. This approach would have obvious limitations when applied to awake children. Free-field is of course worse for standing waves, but I suppose you might ask the subject to move around if the sound is not at first detectable. Then maybe you could calibrate (sort of) by scanning your probe for the peak response in that general region, and hope it's the same peak the subject found. Just a thought. Robert Masta tech(at)daqarta.com D A Q A R T A Data AcQuisition And Real-Time Analysis Shareware from Interstellar Research www.daqarta.com