Part 2G

Acoustics

How To Use Basic Acoustic Formulas

Sound has three basic qualities: velocity, frequency, and power.

Velocity of sound depends on the medium in which it is traveling—in air at sea level it is approximately 1130 feet per second (344 m/sec).

Frequency is the number of cycles completed per second and is measured in Hertz (Hz). (1 Hz = 1 cycle per second.) Since most common sound sources contain energy over a wide range of frequencies, measurement and analysis is often divided into eight octave frequency bands identified by the center frequency. These are 63, 125, 250, 500, 1000, 2000, 4000 and 8000 Hz. For detailed purposes, smaller bands are often used.

Frequency and velocity are related by the following formula.

FORMULA:

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