Question

The eardrum, which transmits vibrations to the sensory organs of your ear, lies at the end of the ear canal. In adults, that ear canal is about

2.5 cm in length. We can treat the ear canal as a tube, closed by the eardrum at one end, and open to the atmosphere at the external end. Consider a fluctuating air column in the canal: similar to a vibrating†string with one fixed end. Its fundamental frequency becomes half that of a string of the same length with both ends fixed. (You can convince yourself of this by imagining a tube with one end closed and the other end open. Sketch the node and antinode of the possible fundamental mode in the tube!)

f_n = nv/4L

Use the above equation to find what frequency standing waves can occur within the ear canal that are within the range of human hearing. The speed of sound in the warm air of the ear canal is 350 m/s. The audible range is 20 Hz to 20 KHz.

Answer 1