Subject: Re: New Scientist Question From: Martin Braun <nombraun(at)POST.NETLINK.SE> Date: Thu, 22 Nov 2001 12:30:12 +0100Laszlo Toth wrote: > A couple of weeks ago I had a nice little ringing tinnitus in my right > ear. (Luckily it went away after a week, just when I started to get > worried about going crazy). > So, I observed that the loudness of my "built-in-sine-wave" increased when > yawning (no change in pitch, however). My physician said the the cause > of tinnitus is usually some inner ear or auditory nerve injury. If so, > how could the loudness be altered by a middle-ear "operation" (yawning)? > Or maybe yawning made all the other background sounds softer and thus > tinnitus seemed to get louder? Very interesting account. 1) What you had most probably was not tinnitus, but a temporary increase in the loudness of a spontaneous otoacoustic emission (SOAE). Tinnitus rarely comes as a sine wave, but SOAEs always do. Many of us experience a temporary audibility of an SOAE that usually lasts only a few seconds. But it can also stay for years. In some cases SOAEs can become so strong that they can even be heard by a second person getting close to the emitting ear. Emitters are clusters of outer hair cells (OHC) in the cochlea. 2) It is well known that both pitch and loudness of SOAEs can be influenced by changes during the reverse transmission of sound in the middle ear. Middle ear air-pressure changes (as in yawning) can also have an impact on cochlear mechanics and thus influence the generation or transmission of SOAEs. 3) According to current knowledge, most cases of tinnitus are based on abnormal activity in the auditory cortex, which developed in the aftermath of an inner ear pathology, usually noise-induced hearing loss. Martin -------------------------------------------- Martin Braun Neuroscience of Music Gansbyn 14 S-671 95 Klässbol Sweden nombraun(at)post.netlink.se