Equal-loudness contours using subjective tinnitus as the standard.

Abstract

For six patients with sensorineural hearing loss and tinnitus, we determined the level of comparison tones (Co) of various frequencies that were judged to be as loud as the tinnitus (i.e., an equal-loudness contour was obtained). To prevent interactions of the Co and the tinnitus, the Co was chosen to lie outside of the region of pitch matches made to the tinnitus. If the loudness of the tinnitus is assumed to be fixed at L sones, then the level, P, of the Co is nearly predicted from the equation, L = K(P - p0).6 where p0 is the absolute threshold of the Co used for the match. The rate of increase of loudness therefore depends on the threshold of the Co: For constant loudness, the larger the absolute threshold of the Co, the smaller is its sensation level. For persons with high-frequency sensorineural hearing loss, therefore, the sensation level of the Co is always smaller in the region of loss than in the normal region. It follows that the sensation level of the Co does not reflect the loudness of the tinnitus; thus, tinnitus cannot be viewed as a weak tone simply because it is matched to a tone at low sensation level.