"rhelsenborg" > wrote in message
...
> On 6/9/2010 4:41 AM, George wrote:
>
>> Good summation here and some test tones:
>>
>> http://journal.plasticmind.com/ears/...ure-a-youngun/
>
> I could hear each of the test tones all the way up to 18 khz. Some of them
> sounded like the tone is wrong or the volume was not at the correct level
> as all of the other tones. I am 50 years old for reverence.

I don't know if they still do it, but here in UK, someone started to play
high frequency sounds at points where young people congregated to drive them
away. They could hear it but not older people.
>

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