Discovering the Mathematics in Sound
Lewis L. Spence
Your feedback is important to us!
After viewing our curriculum units, please take a few minutes to help us understand how the units, which were created by public school teachers, may be useful to others.
How Does the Ear Detect the Source of a Sound?
There are two ways by which we determine the direction of a sound source. This is dependent on whether the wavelength of the sound is much larger or smaller than the distance between one’s ears. If a high frequency sound (shorter wavelength) is coming from the right, the head will block most of the waves effectively preventing more sound from getting to the left ear which in effect producing a louder sound in the right ear as opposed to the left ear. However, in the case of a low frequency sound (larger wavelength), the wave washes over and around the head. In this case the sound intensity in both ears is the same. However, the ear which is closer to the source will receive the sound first which is enough to determine the direction of the sound source. Our ear is capable of discriminating between a time difference of as small as 0.34 milliseconds which corresponds to a difference in distance of 4.5 inches (=11.4 cm). This is based on the fact that the speed of sound in air is 1100 feet per second (344 m/sec.).
