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From: "Tom Izzo"
Date: Wed, 11 Oct 2000 20:58:36 -0500
Subject: Re: [CB] Low Frequency Sound Lens

> Slightly off topic, but of possible interest: the 9/16 issue of New
> Scientist (unfortunately not available on their website) has a small
> article about a new device capable of blocking/reflecting low
> frequency sound.  Apparently, the device consists of a layer of lead
> balls covered with rubber: a single layer is sufficient.  If I
> remember, I'll see if I can dig up the source material...

GRANT!!!!!! Can we come up with something that blocks all high frequency
sounds? say above 2000 cps? :-)



Date: Wed, 11 Oct 2000 19:00:12 +0000
From: Lawrence de Martin
Subject: Re: [CB] [Contra Digest]

> ... you are thinking of an instrument given wind like an organ?  And fingered, handed, or footed like an oversize recorder?

Precisely.  Or maybe it would have an electro-mechanical linkage to cover the holes.

> the most important factors to get right are pressure, pipe length, and pipe bore.... it would be very difficult to get a good sound on more than one single of the fingered notes. Getting a range of more than one octave could hardly be hoped for.

I have been playing with an alto recorder, which has a slightly tapered bore and a Baroque system.  The pressure/flow is very sensitive so it has little dynamic range; or perhaps I'm just a wind klutz.  Anyways, the flow rate of the deca-hexa-contrabass recorder would have to be controlled along with the "footing" of the holes and I would be perfectly satisfied for an octave range for continuo parts.

This opens the possibility of a sextet consort where the top instruments are a contrabass and bass.  If I limit the bore size I can balance the volume against human powered melody instruments.  I am sending this idea out to see if it has been tried and proven unworkable, otherwise it should be attempted.  I thank you for your input on the specific difficulties.

Larry de Martin


Date: Wed, 11 Oct 2000 18:32:53 -0700
From: Grant Green
Subject: Re: [CB] Low Frequency Sound Lens

>GRANT!!!!!! Can we come up with something that blocks all high frequency
>sounds? say above 2000 cps? :-)

Well, sure: that's what egg crates are for :-)  Seriously, screening
or damping high frequency sound is usually not a problem: you just
need something on the order of the sound wavelength to disperse sound
of a given frequency.  The problem is that low frequency sounds have
rather long wavelengths, making them difficult to stifle.  Although I
wasn't really thinking of muffling low frequency sounds so much as
directing them and/or amplifying them...



Grant Green
Professional Fool ->
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