Subject: 1042 Hz Tinnitus From: Peter <pfreihof(at)OPTUSNET.COM.AU> Date: Wed, 7 Aug 2002 08:49:49 +1000Martin wrote: ........................... >Date: Sun, 4 Aug 2002 12:27:26 +0200 >From: Martin Braun <nombraun(at)POST.NETLINK.SE> >Subject: Objective tinnitus due to high-level SOAE > >A question on otoacoustic emissions and tinnitus: > >A 31-year-old electrical engineer wrote to me and asked for help. One year >ago he had a sudden hearing loss in his right ear. Hearing was back to >normal after four weeks, but during this recovery period he had developed a >strong tonal tinnitus in this ear. He was able to compare the pitch of this >tone with an adjustable tone from a tone generator. The ear's tone turned >out to be a sinetone of 1042 Hz. > Hi Martin, from your domain I can see, you are in Sweden. Martin, I'm an Electronics Engineer and am familiar with this particular 1042 Hz tone. In 50 Hz electric power distribution networks, it is common to use a 1042 Hz tone for remote control purposes. This feature is used to remotely control off-peak loads like domestic hot water systems. Every single domestic meter box contains a unit called "1042 Hz ripple control receiver" if an electric hot water system is installed. The 1042 Hz tone is transmitted through the power grid repeatedly during a 24 hour cycle. It would be interesting to know, if this engineer has been exposed (occupationally?) to such mains distributed 1024 Hz tones. Maybe he is employed with a power generation company, hence "close to" the source? BTW, I'm hearing a faint humming noise most of the time with a frequency of 72 Hz. 72 Hz can also be derived from "technical" frequencies, in connection with the 50 Hz power grid. 72 Hz is the third harmonic of 50 Hz 4 pole asynchronous three phase motors (revolving at 24 Hz). 2 pole asynchr. three phase motors run (at) 48 Hz. I can measure 24/48 Hz sound components, and vibrations in my environment - but do not hear these tones directly, nor do others. Could my hum be a product of long term exposure to these frequencies? BTW, I can escape this 72 Hz hum illusion by visiting a quiet valley nearby. The 24/48 Hz sound components are not present in this valley (as confirmed by measurement with a sensitive microphone). It takes about 30 Minutes in this "hum free" environment, until my 72 Hz hum dies away. While it slowly disappears, the typical "modulation" of my 72 Hz illusion disappears first. The remaining very faint 72 Hz steady tone (a residual OAE?) disappears a few minutes later. yours, Peter.