Long-term measurement of binaural intensity and pitch matches. II. Fluctuating low-frequency hearing loss

Thirteen subjects made consecutive long-term recordings of binaural intensity and pitch matches in their homes using portable equipment to assess hearing fluctuations. Two groups of subjects were used; one with monaural fluctuating low-frequency hearing loss (FLFHL) without vertigo, and one with monaural Meniere's disease (i.e. FLFHL with vertigo). The subjects measured binaural pitch matches using a 0.25- or 1-kHz reference tone presented at 60 dB SPL to one ear, and a loudness-matched test tone of adjustable frequency presented to the other ear during one to several weeks. Their results were compared to those previously obtained from ten normal-hearing subjects. Both groups of subjects showed fluctuations in binaural intensity and pitch matches not seen in the normal-hearing group. We calculated the average day-to-day difference in matched intensity and frequency for each subject's test period as a measure of disease activity. This measure indicated that the group with Meniere's disease has a higher disease activity than the group with FLFHL without vertigo, and that both these groups of subjects had higher disease activity than normal-hearing subjects.