Andrew Tan, Ph.D.
postdoctoral fellow
University of Texas at Austin

Katie, AK, CA

Can you listen to an iPod using ear buds in a vacuum?

Since there’s no air in space, there can be no sound waves. My student would like to propose an imaginary scenario: He is floating in space (ignoring that there’s no oxygen and subzero temp) with his iPod in. Can he hear it? I said no, because you’d still need air between the earbud and his eardrum for the sound waves to travel, but we’d like to hear it from a scientist.

Andrew Tan
postdoctoral fellow,
Department of Neurobiology,
University of Texas at Austin,
former HHMI predoctoral fellow
This is a tricky question. After discussion with a senior physicist at the National University of Singapore, it seems that if the earbuds are in contact with the skin, vibrations from the earbuds could travel through the skin to the bones of the ear, which would efficiently pass them to the cochlea. The sound would be much attenuated by traveling through the skin, but it seems that even with an 80-dB attenuation, if the iPod is played at its loudest level of 120 dB, the sound at the ear bones would be a still quite hearable 40 dB. It would probably be distorted, since different frequencies would be attenuated by different amounts. So my inclination is to say that to some approximation, the requirement for air in your ears to hear your iPod is a reasonable one, but I don’t know how good the approximation is, given these considerations. An experiment is probably required to settle this!

03/02/12 11:05