# Sound-affected materials? **URL:** \ **Category:** Factual Questions\ **Created:** [August 14, 2002, 7:50am UTC](https://boards.straightdope.com/t/sound-affected-materials/123809 "2002-08-14T07:50:32Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Aro](https://avatars.discourse-cdn.com/v4/letter/a/b3f665/32.png) [@Aro](https://boards.straightdope.com/u/Aro)\ **Post date:** [August 14, 2002, 7:50am UTC](https://boards.straightdope.com/t/sound-affected-materials/123809/1 "2002-08-14T07:50:32Z")
Is there or is it possible to create a liquid (or viscous material) which is reactive to sound? I mean by this, could a liquid be made to turn solid at the application of a particular frequency or resonance of sound? I haven’t really though of a practical application for such an invention , but the reason I thought of it for those interested is such: I was dreaming of a wax-like material which could be placed n your ears and when I person who you dislike begins to talk, the wax would turn solid and disable your hearing. Stupid, I know. 😉 Anyhow, would it be possible to create such a state changing reactive substance? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 14, 2002, 9:23am UTC](https://boards.straightdope.com/t/sound-affected-materials/123809/2 "2002-08-14T09:23:55Z")
I can’t answer whether it could be done with a single uniform material, but it seems that it would be possible if you allow the inclusion of a little actuator device, which could be some sort of piezo-electric affair. I’m not sure whether such a state-changing material would have significantly different sound transmission properties in each of its states though. ---
**Author:** ![SPOOFE](https://avatars.discourse-cdn.com/v4/letter/s/c5a1d2/32.png) [@SPOOFE](https://boards.straightdope.com/u/SPOOFE)\ **Post date:** [August 14, 2002, 9:42am UTC](https://boards.straightdope.com/t/sound-affected-materials/123809/3 "2002-08-14T09:42:33Z")
A better device - and, in my mind, a bit more practical - would be a device that detects sound waves (gee, they can call it a “microphone”), attach it to a computer that calculates both the source of the sound and the frequency/wavelength/amplitude/whatever, and then, using some really small sound emitters (we can call them “speakers”), emits a counter-wave to that sound. You’d need a helluva computer to do this, of course, and some ultra-sensitive equipment… ---
**Author:** ![Aro](https://avatars.discourse-cdn.com/v4/letter/a/b3f665/32.png) [@Aro](https://boards.straightdope.com/u/Aro)\ **Post date:** [August 14, 2002, 9:52am UTC](https://boards.straightdope.com/t/sound-affected-materials/123809/4 "2002-08-14T09:52:06Z")
Ok. Forget about the silly use of the material I forwarded in the OP. The question was really about the possibility of sound affecting materials and their molecular make-up. I have seen massive LCD screens used in place of vision panels & blinds in offices. To ‘close the blinds’ a switch was thrown to darken the entire wall of screens. (Using the same technology as in digital watch faces). Obviously this change of state in LCD is caused by adding a flow of current. Could this ever be achieved by directly applying particular sounds? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 14, 2002, 9:58am UTC](https://boards.straightdope.com/t/sound-affected-materials/123809/5 "2002-08-14T09:58:44Z")
I daresay nanotechnology (if we ever get there) would make it possible, but that’s just miniaturising the mechanical effect. ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [August 14, 2002, 10:42am UTC](https://boards.straightdope.com/t/sound-affected-materials/123809/6 "2002-08-14T10:42:59Z")
> [@](#): > > \*Originally posted by SPOOFE \* > \*\*A better device - and, in my mind, a bit more practical - would be a device that detects sound waves (gee, they can call it a “microphone”), attach it to a computer that calculates both the source of the sound and the frequency/wavelength/amplitude/whatever, and then, using some really small sound emitters (we can call them “speakers”), emits a counter-wave to that sound. > > You’d need a helluva computer to do this, of course, and some ultra-sensitive equipment… \*\* You mean, basically, phase-cancellation so you would end up with silence? They use a version of this technology on commercial aircraft. Or so my physics teacher has told me. Obviously, it’s not perfect, and only works for a specific frequency band. Also, if you’re out-of-phase with the speakers emitting the phase-cancellation, then you’ll get various effects, like a tremolo-type increase-and-decrease in amplitude (volume).