ABSTRACT
Hearing loss of cochlear origin is usually associated with an abnormal growth of loudness known as loudness recruitment. It is commonly assumed that when loudness increases more rapidly than normal, a smaller than normal change in intensity will be required for a just-noticeable difference (JND). According to this reasoning, the difference limen for intensity might be expected to be much smaller in ears with loudness recruitment. The intensity of a sound is a physical variable that is defined as the square of the pressure divided by the acoustic impedance. The association of loudness recruitment with rapid loudness growth has brought with it an expectation of much lower intensity JNDs for the impaired ear, and led some to conclude that an association between loudness slope and the intensity JND was inconsistent with experimental observations. The agreement between the normal and impaired intensity JND functions was best for the simulated hearing loss when plotted as a function of loudness.
