MUSI 3702 Lecture Notes - Lecture 6: Sound Pressure, Sound Power, Infrasound
25 May 2016
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Document Summary
Infrasound: sound at frequencies below human hearing, around 1 hz. Frequency is one of two parameters to describe sound, the other is intensity (amplitude) Intensity is the sound power per unit of area. Threshold of hearing = io = 10-12 w / m2. The threshold of hearing is arbitrary and dependent upon frequency. If frequency is low, intensity must be high in order to hear the sound. The selection of 1000 hz does bias the db scale against low frequencies. The 1000 hz is selected because the ear canal resonates above that frequency due to the amount of space in the ear canal. Resonance in the ear canal is a result of geometry and wavelength. Standing waves are produced by inference of continuous waves. Open at one end: l = / 4. Closed at both ends: l = / 2. Open at both ends: l = / 2.
