Subject: AC & static pressure feeling From: Sanja Dupor <106744.1511(at)COMPUSERVE.COM> Date: Wed, 28 Oct 1998 13:33:34 -0500Dear list, I agree with Jont that a feeling in AC is as when having static pressure = in external meatus, but: Jont wrote: >When you have pressure on your ears, there is lots of static (low frequency) >pressure relative to high frequencies. He suggests that when you walk in= to >the AC, the high frequencies are damped, but not so much for the lows. >Thus the spectral balance is tilted heavily toward the low frequencies. >It is, he argues, the strong low frequency bias towards the low end of >the spectrum that gives the "pressure effect," just as in the case of >normal high frequencies with a static pressure. > The effect of the static pressure on the hearing threshold was described already in 1972 (Mach&Kessel), and reducing a sensitivity at low frequency's (not influenting high's). Later Bekesy (see: Experiments of hearing, p.360 Fig. 9-49), Disheck and also Rasmussen confirmed (in 50's = ?) that highs are by small positive pressure even amplified (8 dB or so). = In "normal language" - reduced loudness , exactly what happens in AC. Also, my old professor explained always that the threshold of hearing is already optimized and more sensitivity would cause hearing own heartbeat = at lows, brownian movements of air, and blood stream in capillaries. I reall= y don't remember what was responsible for 3kHz or higher. = Zlatan Ribic =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Dr. Ribic Technisches Buero GmBH Vienna, Austria =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D Email to AUDITORY should now be sent to AUDITORY(at)lists.mcgill.ca LISTSERV commands should be sent to listserv(at)lists.mcgill.ca Information is available on the WEB at http://www.mcgill.ca/cc/listserv