BY: Henry Jordan

The purpose of my experiment was to determine how the number of windings in a voice coil affects the volume of a speaker.

My hypothesis stated if there are more windings in a voice coil, then a speaker will output greater volume because there will be more electrical flow (current).

The procedure of my experiment was:

1. Build a speaker with a voice coil made of 50 winds of copper wire.
2. Build a speaker with a voice coil made of 100 winds of copper wire.
3. Apply an 800 Hz sine wave to each speaker.
4. Measure the difference in volume with a microphone.

A speaker is made by wrapping a piece of copper wire (known as the voice coil) around a magnet. By applying an electrical signal to the wire, an electromagnetic field is produced. The wire, attached to a cone, moves with the electrical signal. The cone pushes air waves which is how we hear sound.

The results were that doubling the size of the voice coil produced four times the volume. The speaker with 50 winds on the voice coil produced a volume of 25.2 db. The speaker with 100 winds on the voice coil produced a volume of 44.2 db. This difference is four times as loud.
My hypothesis was supported. I learned that a larger voice coil contains more wire, and that more wire can carry more electrical current, which produces more volume.

About the Author: Henry Jordan, age 9, is the son of Electro Acoustics CEO Luke Jordan, CTS-I. He is in the fourth grade.