Unless indicated otherwise, assume the speed of sound in air to be v = 344 m/s. BIO Energy Delivered to the Ear. Sound is detected when a sound wave causes the tympanic membrane (the eardrum) to vibrate. Typically, the diameter of this membrane is about 8.4 mm in humans. (a) How much energy is delivered to the eardrum each second when someone whispers (20 dB) a secret in your ear? (b) To comprehend how sensitive the ear is to very small amounts of energy, calculate how fast a typical 2.0-mg mosquito would have to fly (in mm/s) to have this amount of kinetic energy.
Solution 13E Step 1: Diameter of ear drum d = 8.4 mm Radius r = 4.2 mm or 4.2x10 3 m Sound intensity level = 20dB Problem (a) Step 1: Energy delivered to the ear I = I 010 10 I0 = 10 12 W/m 2 I = 10 12*10 10 = 10 12.102 10 2 I = 10 W/m