The human ear is a miracle of mechanical evolution. It allows us to hear an astonishing range of sounds and to communicate and navigate in the world. It’s also easy to damage and difficult to repair. Hearing aids are still large, uncomfortable and as yet unable to deliver the rich and wonderful sounds we take for granted. Yet there may be a new way for us to replace damaged hearing from an unlikely source – the insect world.
Spend a summer in the countryside in a warm climate and you’ll likely hear crickets chirping, males of the species “singing” in an attempt to attract a female. What’s surprising is how small the creatures are given the very high sound levels they produce. Could studying crickets allow us to learn something about how to design a small speaker that is also loud, just as you need for a hearing aid?
Currently my colleagues and I are researching exactly this. Crickets create sound by rubbing their wings together. The secret to their loud calls is that their wings are corrugated in specific patterns which makes them very stiff, which in turn makes them very loud when they are rubbed together. Using laser vibration systems and advanced computer modelling simulations (more often used to study aerodynamics), we can replicate this idea by tailoring the stiffness of a speaker surface. This creates a simple and efficient way to make tiny speakers very loud indeed.
Insect inspiration doesn’t stop with small speakers, however. Hearing aids have traditionally been designed to operate in distinct stages. Sound signals are picked up by a microphone and then electrically amplified. Unwanted sounds are filtered out using digital processors and finally a speaker delivers high intensity sound into the ear canal. In each of these processes we may be able to learn from insects.
Rob Malkin, Author provided