[RFI] Actually an AFI Question ...

[doc at kd4e.com]

This is obviously not my field, and a bit off-topic, so based
on no way to acoustically cancel low-frequency sound waves in
the open (yard) then I have to find a way to motivate the
miscreants to turn down the volume.

Which means RF into their sound system to create feedback or
an acoustic discomfort which causes them to suspect their
sound system - thus motivating them to turn it down.

Most vehicles have enough metal left in their shells to be
RF-resistant, so a high-powered high-pitched audio warble,
triggered by their noise, seems the best choice.  WDYT?

One of y'all smart tech-types needs to invent such a critter!

;-)  doc

> On 2/3/2011 1:47 PM, doc at kd4e.com wrote:
>> Can low-frequency audio be canceled using sound?
>
> At a single point, like in noise cancelling headphones. Sennheiser and
> Bose both make some that I would expect to work well.
>
>> I seem to recall someone using sound to cancel echos
>> in a hall to improve the acoustic qualities.
>
> That is pure BS.  Sound and acoustics in public spaces is my field, and
> I can tell you with authority that it is NOT possible.
>> Would it be possible to detect thumpa-thumpa loud car
>> audio and transmit sound that would cancel that sound?
>
> No.  You could reduce the level substantially in your ears with very
> good noise cancelling headphones, but most headphones can't produce
> enough level at very low frequencies to make much of a dent.
>
> 73, Jim K9YC
>
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Thanks! & 73, KD4E
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