I'am not expert audition, or cochlear cells

Bien à vous,

P. De Beer

Dear Vinkata, Aging is an ultimate process for all creature and all organs must pass through this process so in my field dermatology it cannot be doubted that wrinkling of senescent skin is almost entirely the result of changes in the dermis. The debatable questions concern the nature of these changes and the extent to which they are intrinsic or environmentally caused.

The dermis diminishes in bulk, and in absolute terms the collagen per unit area of unexposed skin decreases with age. There also appears to be a steady decrease in the number and size of mast cells and fibroblasts. Gross morphological changes, especially in the collagen and elastin fibres, have been revealed by electron and light microscopy.

There is an age-related loss of fibroblast frequency and size, coupled with a decrease in their synthetic ability.

Over the age of 70 years, there is loss of collagens I and III in the papillary dermis with an associated increase in matrix metalloproteinases. Reactive oxygen species and free radicals are key drivers of degeneration so characteristic of aged skin. This oxidative damage is produced in part by the action of mitogen-activated protein (MAP) kinases. In aged skin, stress-activated MAP kinase activity

is elevated.

The answers above cover most of your question, I would like to add that apart the morphological alterations which occur constantly in the Auditory system (not only above 70y), we have to face the interaction with the acoustic pollution. The latter has raised significantly in the last 50 years and affects all humans. One of the many collateral issues with acoustic pollution is the generation of free radicals which initiate cascade processes of metabolic death in the sensory hair cells. Several factors are important here (gender, race, location) but recently we have evidence that diet can also have an impact on these issues as less and less antioxidants are available systemically.