Abstract
It is well known that the Outer Hair Cells (OHCs) are the first structures to be damaged during excessive noise exposure. The work of the OHCs during noise exposure consumes energy. This energy is produced by chemical reactions within the cell and relies on an influx of substances to the cell. There will also be waste products from the processes that must be removed. If cells are stressed above a certain level they will suffer from metabolic fatigue. This fatigue will damage the cells, either temporary or permanent, and will eventually lead to cell death. A model is presented where the mass transport to and fro the OHC is a diffusion process. The model has the shape of an electric circuit where the voltage and currents are analogs to the concentration and transport of substances. The electrical analog modeling is well established and enables us to predict concentrations and therefore damage and potential cell death. In the assumptions mentioned above it is not important what compounds that need to be transported to and fro the OHC, but literature show that Reactive Oxygen Species (ROS) are central and involved in cell death. If ROS is assumed to be the damaging compounds, anti-oxidants are needed to protect from damage. The model has been compared with the known standards for hearing damage. One of the most obvious advantages of our model is that it will take into account recovery between periods of noise exposure. It is known that the ear benefits from such resting periods but they are not taken into account by the models underlying today´s legislation. Furthermore, if there is a correlation between temporary threshold shift and concentration of damaging compounds (e.g. ROS), this can be used to calibrate the model to each person, eliminating individual differences.
