Project cost ($):
2 days to prepare, 1 day for experiment
Easily found. May be purchased at a hardware store (eg. Home Depot)
Table of Contents
This experiment was done to investigate how the frequency response of a speaker will change using different sizes of enclosure.
Reducing the size of the speaker enclosure will cause the dB of some frequencies to be higher compared to the rest of the frequencies.
The diaphragm of the driver moves back and forth to create sound. The forward movement of the diaphragm will cause the air pressure inside the enclosure to drop and the backward movement of the diaphragm will cause the pressure inside the enclosure to rise.
Diaphragm, decibels, pressure
The materials required for this science fair project:
1. For this experiment, the independent variable is the side of the enclosure and audio frequency played. The dependent variable is the decibel reading of the frequency. The reading is measured using a Decibel meter. The constants (control variables) are the materials used to construct the speaker, the size of the speaker and the distance of the decibel meter from the speaker.
4. A small hole is made at the back of the enclosure using the drill. The wire from the speaker driver is taken out through this hole and connected to the CD player.
The results show that the frequency response of speakers A and B does not go beyond the 0 dB level, but the smallest speaker C will produce some frequencies that are louder than the others. These frequencies show a response reading higher than 0dB.
The graph below represents the results of our science project experiment.
The hypothesis that reducing the size of the speaker enclosure will cause the dB of some frequencies to be higher is proven to be true.
The experiment can also be done by checking the frequency response using different types and thickness of wood for the enclosure.
Speaker enclosure design - http://www.niksula.hut.fi/~mdobruck/siililand/mini/diy/alien/ice/speaker.html