“A Family with High-Tonal Objective Tinnitus” - An Update

In 1971 Glanville, Coles & Sullivan reported on three members of a family whose ears produced externally-audible high-pitched whistles. Although Gold (1948) had proposed an active mechanical feedback mechanism which he postulated might oscillate and cause tinnitus, this possibility did not receive serious attention until Kemp described the cochlear echo phenomenon in 1978. At the time a vascular hypothesis for the whistles appeared most plausible and appeared to be supported by some of their evidence. The whistle components found, ranged from 5.6–14 kHz with a maximum reported level of 60 dB SPL. Most recent investigations of stimulated and spontaneous oto-acoustic emissions, on the other hand, have found them occurring most strongly in the 1–3 kHz range and saturating at, or limited to, a maximum of about 20 dB SPL in the sealed ear canal (Kemp, 1979b, 1981; Wilson, 1980 a, b, c; Wilson & Sutton, 1981; Zurek, 1981). This low saturating level and the restriction of emissions to certain frequency regions, specific to each ear, led to the suggestion of a model (Wilson, 1980ed). based on two hypotheses: firstly, that the signal represents summed activity from the cochlea, and secondly, that the activity might represent signal-synchronous swelling and shrinking of hair cells. For a uniformly-graded cochlea the summed activity would be very small, but with an irregularity in the place/frequency map a large local component would appear in the summed response. Clearly, the existence of emission levels of 60 dB SPL would render the second hypothesis implausible. It was therefore desirable to reinvestigate the original subjects to determine whether their whistles have a similar oto-acoustic origin and, if so, to obtain further clues to the underlying mechanisms.