[Gllug] Yoof got mail

[j.roberts]

Perhaps unwisely, taking this seriously (yes it's Friday)...

David L Neil Mailing list a/c wrote:

> Is a PC's built-in speaker able to produce sound at frequencies above
> the capacity of the average adult, but within that of a young person, to
> hear - and are such 'you got mail' messages available on the web?

No.

The typical small speaker used has an effective HF limit in the low kHz, 
say 8-10kHz, and is a good 10dB down by then. I've tested them.

The even-smaller piezoelectric or magnetic units found in newer Dell or 
HP machines have an even lower limit.

...

> Apparently 'the kids at school' had a wheeze of a cell phone ring tone
> which ran only at a high frequency - and thus they were able to receive
> SMS even after the teacher/school had banned such, simply because they
> could hear the clarion call whereas the adults remained oblivious...

I suppose this is meant:

http://www.teenbuzz.org/

Teacher was probably a bit deaf. Hearing varies between individuals, I 
(at 58, but an ex-studio-desk engineer and producer) can still detect 
presence/absence of 16kHz.

Age-related hearing loss is complex and variable. There is no simple 
graph available for this. Best I can do is:

http://www.usouthal.edu/alliedhealth/speechandhearing/ramkissoon/AUD643_Aging/stenklev_2004.pdf

OTOH I have tested would-be sound engineers who were deaf above 10kHz at 
22 years old - don't turn your headphones up too high, kids!

http://www.abelard.org/hear/hear.php

> He asks, as if I have ANY IDEA, if such a thing can be done on a PC? I
> wouldn't have thought that the little utility-beep speaker would be so
> responsive (and he doesn't (yet) have any external MM speakers and nor
> is the boss (currently) of a mood to add them given the current
> atmosphere of complaint...). Does this make the remotest amount of sense
> or am I sleepless in Seattle? Anyone know anything about such frivolities?

In principle it is certainly feasible but not really with the PC 
speaker. This could be replaced (with a cheap tweeter say), but the beep 
circuitry is crude in the extreme. It could however be done.

Given any typical audio system it should be feasible to let out an HF 
mail yell in the range above 16 or 18kHz which most people older than 3 
will not be likely to hear.

Implementation is left as an exercise for the demented or desperate...

:)

-- 

James Roberts
Stabilys.com
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