Zwicker effect

r norman rsnorman_ at _comcast.net
Wed Jun 4 07:36:20 EST 2003

On 4 Jun 2003 00:39:15 -0700, tonyjeffs at aol.com (TonyJeffs) wrote:

>r norman <rsnorman_ at _comcast.net> wrote in message news:<o9bqdvg2nh04bt9gl53fjslqsndo4mpgjl at 4ax.com>...
>> A lot of the tinnitus speculation assumes it is a peripheral
>> phenomenon.  That is, there really is a sound to be heard or else that
>> the hair cells (or auditory nerve neurons) are generating it.  What if
>> it were a central process?  I was told that my situation was most
>> likely caused by the ABSENCE of auditory nerve activity -- the central
>> auditory centers "didn't like" the absence of normal stimulation and
>> took things into their own hands.  That is, the frequency range of the
>> ringing was higher than my upper limit of hearing.  Over the years as
>> the my high frequency cutoff dropped lower and lower, so did the
>> tinnitus tone.
>I accept the possibility of centrally generated tinnitus, but feel
>there are a lot of arguments against it.
>1. Research in that area, eg Salvi & Lockwood, which suggests that
>'tinnitus is central' invariably looks at tinnitus *perception* rather
>than generation. eg lymbic or colliculus involvement.  This is imo a
>shortcoming in interpretation by the researchers... I'm not aware of
>any research  properly suggesting central generation.
>2. Beyond the retina and the cochlea, the sensory components become
>structually very similar. If a centrally generated auditory signal was
>common (esp in healthy people), one would expect a centrally generated
>visual signal to be common. Pain too.
>3. As in argument '2' , it is common to have louder tinnitus in one
>ear than the other. It is common to have it in a specific frequency
>range, and similar frequency ranges are found in groups of people. 
>Beyond the assymetrical cochlea, there isn't a great physical
>difference between the high frequency pathway and the low frequency
>pathway. If tinnitus was central, one might expect a totally arbitrary
>distribution of frequency.
>4. Tinnitus can be caused by physical injury to the ear.
>I think there is often a blurring of the concept of tinnitus
>generation, and tinnitus perception.
>Counter arguments to mine are:
>1. Profoundly (??) deaf people have tinnitus to the same extent as
>hearing people. So it must in some cases be central.
>2. Phantom limb pain is, by definition not in the severed limb, so it
>must be central. Similar phenomenon.
>In conclusion, there are 4 arguments above supporting my case , and
>only two opposing it, therefore I must be right ;-)

I humbly yield to someone who actually knows what he is talking about!
Whatever the source, it really is annoying!  Actually, mine is usually
acceptable -- I can just ignore it unless I am feeling particularly
irritable.  I hear that it can be really intolerable in some people so
I am fortunate.

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