Which of the following values represents interaural attenuation for supra-aural earphones?

Interaural attenuation refers to the reduction in sound intensity that occurs when sound travels from one ear to the other through the head. For supra-aural earphones, interaural attenuation is generally accepted to be around 40 dB. This means that when a sound is presented to one ear through these types of earphones, approximately 40 dB of that sound intensity will be lost as it crosses over to the opposite ear.

This is a crucial value to consider when interpreting audiometric results, as it helps audiologists determine whether a response is coming from the ear being tested or if it might be attributable to sound crossover to the other ear. Understanding this concept is vital for proper testing and diagnosis in audiology, ensuring that the results reflect true hearing ability rather than unintended auditory responses from the non-test ear.