Re: [Phys-L] non-linear ears.

[bernard cleyet <bernard@cleyet.org>]

Sorry, the brand name of an English public address system.   It’s like to hover, instead of vacuum clean.  

In this case not so “public”.  

bc wonders why it’s vacuum clean instead of suction clean, and suck using a straw instead of vacuum up a drink.  

> On 2020/Oct/09, at 06:45, Brian Whatcott <betwys1@sbcglobal.net> wrote:
>
> This note suggests that in the usual way, an audio modulated ultrasonic acoustic wave is inaudible to the ear, but audible to the usual microphone, such as yours.

No, the voice was quite audible, I wasn’t deaf then.  The “beam” was only about a foot wide at a coupala yards away, i.e. ~ 0.1 radian.  (6 deg.)


> Brian W
> Secret Ultrasonic Commands Can Control Your Smartphone, Say Researchers
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> Secret Ultrasonic Commands Can Control Your Smartphone, Say Researchers
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> Voice-controlled digital assistants are increasingly common and sophisticated. Google, Apple, Amazon, numerous c...
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>    On Friday, October 9, 2020, 01:35:59 AM CDT, bernard cleyet <bernard@cleyet.org> wrote:  
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> A friend reminded me of a demo. at the Naval Postgrad. School, wherein an ultrasonic speaker generated wave is voice modulated in order to produce a rather narrow bean Tannoy.  I presume it works by the ear’s being non-linear in amplitude response.  Any idea if it would work W/a hearing aid that has no gain above about 8k Hz?  
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> bc  whose hearing is about 60 dB down.  
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