I wonder if anyone would care to take a shot at this one: Well I am going to try. Here we go again. There are two kinds of deafness--nerve deafness and conductive deafness. In nerve deafness, the problem is damage within the cochlea, the auditory nerve or at some higher level. Conductive deafness is due to impairment before this point, usually in the middle ear. The nerve transmission part remains ok. So it would seem that a hearing aid would be useful for conductive deafness but not nerve deafness, and this is what most elementary textbooks say. One curious exception is the text I use (Kalat, 1995, p. 240) in which Kalat mentions hearing aids only in reference to nerve deafness and says that they "can compensate for the loss". My first opinion was that Kalat had reversed his statements and dismissed his statement as an error. But consider this, a viberation of the sounds your are being exposed to under your forearm will increase hearing. Most likely due to wavelet entrainment. So any procedure that helps with wavelet entraiment should help in principle. Therefore a hearing aid would help provide the wavelet signal strengthen to help in the the hearing process. Consider the large number of nerves cells going to the hearing system from the brain. They are doing something. I would suggest correlational opponent-processing. Nevertheless, some knowledgeable sources do say that hearing aids may also be of value in nerve deafness. For example, Moore (1982) says that "the condition [of nerve deafness] is usually not completely alleviated by a hearing aid", which implies that it does help. Of all the sources I've looked at (physiological psychology textbooks, specialized texts in hearing), the most detailed statement I've found is in Matlin and Foley (1992, p. 267-68). They say "A hearing aid would be useful for people with moderate levels of conduction deafness" [no problem there]. Then they say "A simple hearing aid would not help someone with complete nerve deafness, just as a pair of glasses would not help someone who has a detached retina [my understanding, also]. But then they say "Furthermore, if some hair cells are intact, a standard hearing aid can be modified so that it differentially amplifes the different frequencies" and go on to say "Thus, the design of a hearing aid for a nerve-deaf person must take care of two problems..." [45 lines left ... full text available at <url:http://www.reference.com/cgi-bin/pn/go?choice=message&table=05_1997&mid=2169845&hilit=BRAIN+FEEDBACK> ] -------------------------------- Article-ID: 05_1997&2164862 Score: 78 Subject: Re: Equilibrium and destabilization in evolution (long)