Low and High Frequency Attunate Science Fair Projects

Methods/Materials

To measure attenuation I constructed a sound insulated testing cube which was open on one side containing speakers connected to an electric piano used to generate different frequencies of constant volume. A sound meter was placed on a tripod at various distances to read decibels for each combination of sound attenuating material, distance, and frequency.

Results

As hypothesized, (1) high frequencies attenuated more than low frequencies and (2) fiberglass, a soft material, was one of the best sound attenuators. However contrary to hypothesis, the hard materials of wood and cardboard were equally good attenuators and Styrofoam, a moderately hard material was the worst attenuator. Contrary to hypothesis, sound does not attenuate linearly with distance as in circular spreading; instead it attenuates with the square of distance as in spherical spreading.

Conclusions/Discussion

The attenuation of all the hard materials was very similar in spite of differing thicknesses. Perhaps they are acting more as a reflector than an absorber. I#d like to test this further by adding thickness as a variable and by measuring the sound inside the chamber rather than just outside. 3rd party contributor