Smoke Mic Prototype One

World's first laser-smoke microphone prototype of U.S. Patent 7580533. Noisy and rough, but like a talking dog, the main thing is, it talks.

Category:

Science & Technology

Tags:

• Schwartz Engineering
• Microphone
• Laser
• Smoke
• New Microphone
• AES
• IEEE
• 7580533
• Patented microphone
• David Schwartz
• Audio
• New Technology

[SvenTwelve]

also, consider varying the size and shape of the flat bubble, though a circle will probably be ideal.

[imon2nd]

Hello, Sven.

The soap bubble or very thin film idea is a good one that has been implemented before, though with a polymer material. Take a look at Sennheiser's laser mic, which uses a Mylar film diaphragm.

Of course, I'm developing mics with no diaphragm so I'll leave the improvements in the previous technologies to others.

Best Regards,

David

[jahcriado]

I'm wondering how you could make this more... conventional looking. I could see it working fine if there was a way to do a permanent suspension in air & have the laser shine through it, but I have not seen a gas mix that stays suspended & not condensing or the ratio fluxing. Could a liquid solution be used?

[imon2nd]

Hello, jahcriado.

Liquid won't work because it is practically incompressible; the sound pressure waves don't change the density of the liquid enough to "read."

A permanent suspension of particles in gas is too noisy; reverberation is uncontrollable and the pressure waves in the medium become chaotic.

A moving "ribbon" of smoke or fog gives the pressure waves something to "write" on that is always a clean slate, provided the ribbon moves fast enough.

This type of mic can look conventional.

[synthtubedotcom]

This is great, but... Not to be a curmudgeon, but.. For a so called "Audio professional", the standard and quality of your audio on these videos is absolutely unforgivable. Hire a real sound recordist next time.

(Audio professional with 15 years experience)

[imon2nd]

synthtube;

You're right. Sorry about that.

We're upgrading our AV production values for the Prototype Two clips. Coming soon.

Cheers,

Dave

[SvenTwelve]

also consider hitting the (flat) bubble with the laser in a variety of locations using multiple beams and separate detectors, since the bubble will multiple harmonics simultaneously (like a drumhead), as opposed to the simple fundamental harmonic (i.e., measuring in a single location would provide only a slice of the harmonic wave content on the flat bubble).

[SvenTwelve]

you could probably create a reflective "mirror" (flat) bubble, and hit it with the laser at an angle. this would enable you to measure amplitute very accurately using an array of photo detectors.

[SvenTwelve]

you can probably find a better solution than water and soap to make the flat "bubble", i.e., one that makes a longer-lasting bubble and one that has minimal (lateral) surface activity.

[SvenTwelve]

use a *flat* soap "bubble" suspended on a ring for a diaphragm and shine the lazer through the flat soap "bubble".

[SvenTwelve]

don't use smoke.