Sound Study Guide

Homework Help

• what type of wave a sound wave is, and that it needs a medium for its propagation
• the meaning of the terms ultrasonic, infrasonic, intensity, loudness, pitch, beats, forced vibrations, sympathetic vibrations harmonics, sonic spectrum, audio spectrum
• what intensity is proportional to and in what way (directly or inversely)
• the laws of strings and be able to use them to solve a simple problem
• that pitch depends on frequency
• the direction of the particle motion in a sound wave
• what the speed of sound in air depends upon
• what effect changing the distance from a sound source has on the intensity (inverse square)
• what effect a change in sound intensity will have on the decibel level (say by a factor of 100 or 1000)
• how harmonic content relates to sound quality
• the harmonics produced by closed and open tubes
• that beats are caused by interference
• what determines the upper limit of the sonic spectrum

and be able to calculate:

• the frequency from a given wavelength and wave speed
• the beat frequency from two given frequencies
• the change in relative intensity (dB) from a doubling of power
• the speed of sound at a given temperature (speed at 0 degrees given)
• distance of lightning strike given time between strike and thunder
• the power of a sound source given the decibel level at a given distance
• the speed of a sound source, given the normal and perceived frequencies