Each is out of phase with the other. Regions of destructive interference emanate diagonally from the tines as they vibrate. Hence, changes in sound intensity can be heard when a vibrating tuning fork is rotated near the ear. The reverberation of sound in a room may produce regions where differences in the levels of sound intensity can be a problem. The beat frequency depends on the difference in frequencies between the two sources.
Musicians can use their understanding of beats to tune musical instruments.
Explain that all objects have a unique natural frequency of vibration. Explain that a periodic force occurring at the same frequency as the natural frequency of vibration of an object may cause the object to begin to vibrate. Explain that the periodic force and the object being affected must come into contact for mechanical resonance to occur. Explain that mechanical resonance may cause objects to undergo failure. Suggest ways in which the failure of an object due to mechanical resonance can be prevented.