Subject: Re: Help: using mics as earphones From: "Daniel J. Levitin" <levitin(at)INTERVAL.COM> Date: Wed, 6 May 1998 14:34:47 -0700Daniel - It is possible to use a microphone as a loudspeaker and vice - versa. As transducers, each of them is involved in the transformation of one kind of energy to another. The microphone's diaphragm responds to pressure in the air by moving in and out and the in and out motion is converted to a continuous analog voltage. When the voltage is applied to a speaker, it turns the electrical energy into a pattern of in and out motions that cause vibrations in the air roughly analogous to those that caused the microphone to vibrate in the first place. The problem you might experience is that microphone diaphragms are very sensitive (by necessity) and if you try to drive one "in reverse" it will work, but only with very small input voltages -- if you try to make it too loud you'll blow it up. Microphones and loudspeakers are optimized in their design (including factors such as damping) to do what they were intended to do. There are some commercial "dual purpose" devices that are microphone and loudspeaker built in one, and Radio Shack used to sell something like this. If what you're looking for is a really tiny speaker, though, I suggest you look at some of the products that were designed for that purpose, such as those sold by Etymotic Research. Dan Levitin ============================================== Daniel J. Levitin, M.Sc., Ph.D. Phone: (650) 842-6236 Interval Research Corp. FAX: (650) 354-0872 1801C Page Mill Road email: levitin(at)interval.com Palo Alto, CA 94304 Lecturer, Departments of Music, Psychology and Computer Science Visiting Scholar, Center for Computer Research in Music and Acoustics Stanford University, Stanford, CA 94305 Please note: After July 8 my email address will be levitin(at)ccrma.stanford.edu Home Page: http://www-ccrma.stanford.edu/~levitin ================================================