Noise-enhanced sensitivity of mechanical detection in the auditory system
The inner ear is a remarkable detector of sound waves, sensitive to signals that vary over 3 orders of magnitude in frequencies and 6 orders in pressure. This detection furthermore occurs in a noisy and highly viscous environment, as the sensory cells – the hair cells – are immersed in a fluid compartment, at room temperature or higher. It was proposed that this sensitivity is achieved by poising the system close to a critical point described by a Hopf bifurcation. I present a new model based on a different bifurcation that can likewise act as an amplifier, and compare the performance with previously suggested models as well as with experimental data, obtained both in vivo and in vitro. This new approach leads to predictions that are in agreement with experiments. In addition, I will demonstrate that ambient noise enhances the detection sensitivity of this mechanism.