From:	Marc Renouf <renouf@********.COM>
Subject:	Re: Ultrasound vision
Date:	Wed, 3 Feb 1999 16:49:36 -0500

On Wed, 3 Feb 1999, David Woods wrote:

> How is this achieved?
>
> Would that be done with the acoustic equivalent of a lens, parabolic
> mirror or something else?

Well, a microphone's "focus" tends to be a physical/electronic
property. I have seen crude "sonic lenses," though. They're
essentially just an object designed to bend sound by passing it through
materials of varying density. Pretty wack.

Marc