Nightclubs and personal stereo headphones are the biggest cause of noise induced hearing loss among civilians. The tests over the telephone may give false positives for hearing loss. The bandwidth of human hearing is about 20 kHz although at the high end of the spectrum this only conveys nuance information The Plain Old Telephone Service is designed to convey intelligible speech with the minimum bandwidth. Intelligible speech has a bandwidth of about 3kHz and is between from about 300 Hz to somehwere in the region of 3kHz. Music on the otherhand uses most of the spectrum between the mid 30s and the end of the audio spectrum towards 20Khz. The public telecommunications service local loop was only designed to convey the 3kHz bandwidth frequencies and not the higher frequencies present in music. Although the local loop/subscriber loop may carry higher frequencies, (the 64kbps voice circuits in the PCM system of the network can) the telephone instrument itself may not have a high enough bandwidth speaker to convey the test frequencies. In conclusion is end to end telephone circuit may not actually be carrying the higher frequencies and may give a fals positive hearing test result. Hearing loss of the noise induced variety (c.f. other factors such as old age and menieres syndrome which exhibit Low Frequency hearing loss characteristics) is always signified by loss of hearing at high frequencies. The shorter hairs, which are weaker, particularly the more sensitive cochlear hairs are damaged. The shorter hairs because of their higher resonant frequency are responsible for picking up higher frequencies. Hearing loss is irrevesible and permanent Another hazard of high volumes is tinnitus. It can be a very debillatating condition, a friends father has had clinical depression because of the sleepless nights from Tinnitus. For a proper hearing test see an Audiologist. Any of the hearing aid shops can provide a professional test. Discreet musicians earplugs are available which filter the high volumes at a constant attenuation across frequency. They come in various attenuations including for example from a company called Elacin or Elcea. <website quote> For vocalists in noisy bands ER - 9 earplugs For musicians and disc-jockeys Elacin R-15 & ER-25 musicians earplugs For nightclub visitors Elacin ER-15 musicians earplugs For motorcyclists Elacin biopact <website unquote> They are custom moulded to the user's ears. There is no loss in musicality only attenuation in volume. I'm not connected with Elacin in any way. I have a pair of their ER-15s which I bought after being diagnosed with noice induced hearing loss at an RGIT medical. Some useful links: http://www.tinnitus.org.uk/information/info%20sheets/front%20page/suppliers.htm http://www.hearnet.com/index.shtml I am advised ABERDEEN INDUSTRIAL DOCTORS fit musicians plugs at well under market price as they get them in bulk for their oil company clients..
