Context effects in loudness

Bertram Scharf made contributions to numerous topics in the loudness literature. In particular, he brought a great deal of insight into the current understanding of contextual effects in loudness. Some of the contextual effects that he studied include: (1) loudness adaptation, the decline in loudness of the latter portion of a continuous sound, (2) induced loudness reduction, the phenomenon by which a preceding stronger tone reduces the loudness of a weaker tone, (3) temporary loudness shift, a decline in the loudness of weaker sounds due to a physical fatigue of the cochlear amplifier, and (4) loudness enhancement, in which a brief sound is made louder when it follows a stronger sound within a short duration. Context effects serve as complex reminders of the necessity of careful design of any psychoacoustical experiment in which level varies. These effects also result in the breakdown of all loudness models, as virtually all calculations of loudness are performed for sounds without regard for previous stimuli. [Work supported by NIH-NIDCD.]