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AUDIO FORUMS >> General Discussion and Support >> Breaking the Soundbarrier
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Message started by Azul Shiva on 08/17/14 at 01:29:14

Title: Breaking the Soundbarrier
Post by Azul Shiva on 08/17/14 at 01:29:14

Hi

LOL strange title. But heres a question:

If you have a normal subwoofer capable of 10mm excursion at 50hz, it means the membrane is moving at around 1/600th the speed of sound. Imagine you had a membrane, infinitely high and wide, capable of any speed and acceleration in an earthlike infinite atmosphere. Now if you play 50hz over that membrane and increase the volume it should simply get louder. Sound energy is merely kinetic energy going back and forth, now if you adjust volume until it moves at above the speed of sound (around 6m excursion dont touch that speaker LOL) the kinetic energy directly applied to the air at the membrane is higher then the energy a sound wave can carry.
Ive had some discussions with a mate and we came to very little conclusions.

http://t0.gstatic.com/images?q=tbn:ANd9GcQVcZ3JRasdgZJgRrKVoApQXdWN_5Duf2ewDfwyqXixbQ0laQIH

If you increase volume in the diagram above, A will get denser, and B will get voider. However as you increase the volume above MACH 1 membrane movement, there is too much energy stored in A that the wave cannot transmit. The sound will not turn into Impulses, nor will a sine Wave turn into a square wave as in digital volume distortion. One idea would be, the remaining energy turns into heat. Or that the Air in A will move into B, distorting the sound? How? Or will paradoxically the volume decrease as you go above Mach 1? Will it turn into white noise? As I am not a physist or anything, there are a lot in here, I am pretty clueless. Can anyone answer this?

How would it sound like, or rather, how would the waveform look like (I guess a sound at that volume would just tear you apart and turn you into stew) at MACH 1? What kind of distortion do you get when getting close to MACH 1? And eventually what would happen when the membrane goes above that speed?

Thanks for any answers already. Cant wait until someone replies!!
gratz, azul

Title: Re: Breaking the Soundbarrier
Post by mark58 on 08/17/14 at 01:38:34

Methinks you think too much!

Title: Re: Breaking the Soundbarrier
Post by marky on 08/17/14 at 10:49:37

It`s been a long time since I fantasized about Pink Floyd using PA`s the size of small planets floating in the stratosphere while they played, enabling billions of people to go about their day to day lives while being bathed in the Floyd. Nowadays it`s all I can do to wonder how a speakers membrane/diaphragm can play multiple instruments all at once...the membrane moves out with one note at the same time another note piggybacks on etc etc... I cant get my head round it but then it`s not my job to :) ( I must get some shunting yard albums )

Title: Re: Breaking the Soundbarrier
Post by Azul Shiva on 08/17/14 at 11:40:18

ooohh please guys, i know theres ppl in here with very nice brains that studied physics and acoustics and that..

anyone help please? :(

Title: Re: Breaking the Soundbarrier
Post by marky on 08/17/14 at 13:52:59

The sound coming out of a speaker is...mach 1 or 1100ft/sec. Thats the speed any sound travels at outside of a vacuum. How far it travels ....or how loud it is, is obviously whats doing it...a microbe making a noise right up to Krakatoa exploding. To recreate Krakatoa you`d need some serious hardware. It could be done if someone was rich enough to indulge in a, lets say, a scientific experiment. Huge liquid oxygen cooled ganged amps and speakers able to cope could be designed on paper and distortion levels kept in spec. Being next to Krakatoa would turn you to stew ( though I`m speculating )
Being further away would also do serious damage. ( check out Munch`s " The Scream" said to be the moment it erupted )

Also Tesla, much loved by tech students getting their heads round magnetism created by passing current through coils. He did some pretty wierd stuff with low frequencies and it`s said had to be put paid to by some gvnmnt or another.

Beaking the sound barrier is for objects that go faster than 1100ft/sec, not the actual sound. The sound (bang) of a jet breaking the sound barrier still only goes at mach 1. eg a `whip crack`.