Laser Inferometer Measurement of Acoustic Phase

[Bennett Prescott]

If you haven't seen this floating around the Interwebs, it is extremely cool:

NPL and PMC pioneer new loudspeaker measurement

The NPL site has much more detailed information, and more importantly two great videos demonstrating this technology. This allows mapping of the behavior of sound around a loudspeaker at a resolution never before possible. Of course, it likely costs more than ever before possible as well. Really nifty to see the handoff between the two bandpasses in the example.

Here's their poster on the technology, written by Ian Butterworth - no idea if he's related to Stephen Butterworth!

Seeing Sound: Exploiting the Acousto-Optic Effect : Science Posters : Publications : National Physical Laboratory

 

[Bennett Prescott]

Re: Laser Inferometer Measurement of Acoustic Phase

Here's another video that's a little less polished, but has more data:

 

[Ivan Beaver]

Re: Laser Inferometer Measurement of Acoustic Phase

It really shows how the sound from 2 physically separate drivers (woofer and tweeter) interfere with each other and produce different "ripples in the pond".

However I didn't see anything about the coverage pattern that he started talking about in the intro.