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In the mechanical part of the human eye the control system to protect for overload of the diaphragm in the iris with a strong coupling to the light intensity that falls on the retina has his place in the visual system as close as possible to the light source in the chain of control devices of the human visual system. The iris is disk-shaped and consists of two muscles. Like a diaphragm for light, the iris regulates how much light comes into our eyes. In bright conditions, the muscles of the iris limit how much light comes in. In lowlit conditions, the muscles of the iris increase the amount of light comming in.

Basic hypotheses is that the protection device in mammalian human hearing system is based on similarity as in the visual system and therefore should well also be using similar protection tools as used in the visual system and should well also be placed in the chain of control devices as close as possible to the signal source, as an experienced system engineer will always place a protection device in the chain of control devices as close as possible to the signal source.

Exists such an continuous functioning simalarity analogue in the protection system for sound signals ? Both the iris in the eye (two muscles) and eardrum+ossicular chain in the ear (two muscles): in protection. Exists that similarity ?

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I'm not sure what the question is, yes the ossicular chain is believed to have a function as 'overload protection' - but I feel you're aware of that already. Could you clarify at all? –  Rory M Jan 4 '13 at 22:45
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The cooperative functioning of the eardrum and ossicular chain attenuation can be regarded as in this schematic drawing of the ear as an externally activated spring-mass system. Fig. 2.

Ossicular chain and eardrum function, together operating as a continuous sound reduction mechanism for changes in the strength of the offered signal. The tympanic membrane and the ossicular chain can be seen as a spring-mass system with amplification facilities, like it is shown in this figure.

The combined action of the ossicular chain and the eardrum is hypothesized to provide for both permanent volume control of the input sound and for overload protection. The stapedius reflex, evoked by sudden strong sound signal, cannot be seen as anything else than an extreme manifestation of the very mechanism that the schematic drawing of the ear as an externally activated spring-mass system propose.

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