On the relation between the acoustic reflex and loudness

Dynamic study of the acoustico-facial reflex by impedance measurement

Dynamic study of the acoustic reflex has brought into evidence that 1. age has a significant influence on various reflex response parameters 2. study of dynamic parameters of the acoustic reflex enables changes in the reflex arc to be objectified. This is therefore an objective measurement of recruitment in impedance measurement. The author proposes to study the following parameters: rise time, recovery time, and the variations of maximum amplitude as function of sound stimulation intensity. Study of these three parameters provides a highly sensitive test of change in the dynamics of the acoustic reflex, for indeed this test reveals pathology well before the Reflex Decay Test does so.

Effect of signal bandwidth upon threshold of the acoustic reflex and upon loudness

The effect of activating-signal bandwidth upon the threshold of the acoustic reflex (TAR) was measured. Subsequently, loudness measurements were made for the same signals at the same intensity levels that were required to elicit an acoustic-reflex response. When loudness and TAR are compared at comparable levels, similar trends emerged. Results from this experiment provide evidence for both qualitative and quantitative similarities between acoustic reflex and the perception of loudness. This, in turn, suggest that signals at TAR may be equally loud for listeners with normal hearing.