PHYS 101 Chapter Notes - Chapter 12: Longitudinal Wave, Standing Wave, Logarithmic Scale
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PHYS 101 Full Course Notes
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Sound travels as a longitudinal wave in air and other materials. In air, the speed of sound increases with temperature; at 20 c, it is about 343 m/s. The pitch of a sound is determined by the frequency; the higher the frequency, the higher the pitch. The audible range of frequencies for humans is roughly 20 hz to 20,000 hz (1 hz = 1 cycle per second). Intensity of sound: decibels are specified on a logarithmic scale. The loudness or intensity of a sound is related to the amplitude squared of the wave. Because the human ear can detect sound intensities from (cid:883)(cid:882) (cid:2869)(cid:2870) w/(cid:2870) to over (cid:883) w/(cid:2870), sound levels. The sound level , specified in decibels, is defined in terms of intensity as: Where the reference intensity (cid:2868) is usually taken to be (cid:883)(cid:882) (cid:2869)(cid:2870) w/(cid:2870). Source of sound: vibrating strings and air columns. Musical instruments are simple sources of sound in which standing waves are produced.
