A tiny sensor that mimics how the cochlea in the human ear works could be used for hearing aids or microphones that can pick out sounds in noisy environments.
The cochlea can adjust how sensitive it is to certain frequencies depending on the volume of the sounds it picks up. If you are in a busy restaurant, for example, it will alter how its hair cells react to the frequency of sound from a person sitting across from you so you can hear it above the background noise. Some software can mimic this ability to a limited extent, but it is less effective if the desired sound and the background noise are at similar volumes to start with.
at the Ilmenau University of Technology in Germany and her colleagues have designed a miniature electrical sensor that can automatically adjust its sensitivity to different frequencies through a feedback mechanism.
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鈥淚t鈥檚 the first real sensor which integrates the processing that happens in our inner ear directly into the sensor,鈥� says Lenk. 鈥淭hat makes it quite efficient and faster than typical set-ups that were developed before.鈥�
The sensor, which is about 350 micrometres long and 150 micrometres wide, consists of a strip of silicon that can convert sound waves into electrical signals of different frequencies. The strip is connected to an actuator that can change how it responds to different frequencies. This means the sensor could adapt if someone was moving from a quiet office to a noisy street, for example.
The team hopes the device could eventually be used as a component in a hearing aid as good as the human ear. But each sensor can only work over a small frequency range, so you would need 30 to 60 sensors to cover the range of human hearing, says Lenk.
at the University of Strathclyde in Glasgow, UK, says the device is a neat combination of technologies to replicate some of the function of the human cochlea, but it will need to be miniaturised to fit inside the ear. 鈥淚t鈥檚 a component of a cochlea, and then if you replicated that, you can make yourself a cochlea, but at the moment it鈥檇 be quite a big one.鈥�
Nature Electronics
