Subject: Testing whether some humans can hear high frequencies inaudible to "normal" humans From: Kevin Austin <kevin.austin@xxxxxxxx> Date: Tue, 15 Jun 2010 11:03:50 -0400 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>Perhaps the first test is of the adults' hearing. If the child is (say) between 5 and 7, the parents would be in their late-20s to early 40s. This generation has been exposed to abusive sound pressure levels for 20-30 years. Maybe their threshold of hearing is around 40dB with upper frequency response of 7 kHz. There are people on this list who see this every day, and could probably let us know the rate of increase in the past two decades. I have had classes (with 17 - 22 year olds) who winced and complained about 15-18kHz signals which I could barely detect. As a child, I too had hyper-sensitive hearing and would often be woken by "the lions roaring in my ears" -- my circulatory system. Kevin