How to Make a Microphone From a Speaker

Microphones and speakers are reciprocal devices-that is, they can both operate as one or the other. A microphone or a speaker is like an antenna for sound: It converts sound into an electrical signal or vice versa. You can easily make a microphone from a speaker, and, with a little ingenuity, you can actually make one with reasonably good characteristics.

Instructions

1. Realize that the principles behind the operation of a microphone and the operation of a speaker are the same. The only difference is that the design of a microphone is better at converting sound to an electrical signal, and a speaker is better at converting an electrical signal to sound.

2. Connect the speaker's two wires to the appropriate type of microphone connector. The type of connector you need depends on what you're hooking the microphone up to.

3. Plug your new microphone into some type of amplifier (a radio with a microphone jack is sufficient) and test the results.

4. Modify the speaker to get the type of sound you want. This may require removing the speaker from its housing or building some kind of structure to better direct the sound or to provide improved acoustics.

Tips & Warnings

• The directivity (how the speaker directs the sounds it produces or from what directions the microphone best receives sounds) and the frequency distribution of the speaker may not be precisely what you want for a microphone. You can make some adjustments to these characteristics with some simple materials, but you probably won't ever get a professional microphone out of a regular speaker without spending a lot of money.

• A speaker can only act as a passive microphone. That is, unless you add some additional amplification circuitry (which you can easily do), you may not get a strong microphone signal out of the speaker.