Exciting animals

The window of opportunity is very narrow. Sound travels furthest in the sixty minutes before sunset, and it is precisely during this hour that animals of all species, from frogs to crickets, seek a companion for the night. They should actually all be croaking and crowing and chirping at the same time – “but that would make a terrible racket and wouldn’t help anyone”, says Sonova’s hearing research specialist, Stefan Launer, Senior Vice President Audiology and Health Innovation. The animals have hit upon a solution to this dilemma, however; they divide up the hour, taking it in turn to broadcast their “lonely hearts” notices.

The technical term for this is ecological adaptation, and these creatures’ “rush hour” is one of many examples demonstrating how crucial hearing is to animals and humans alike. “The animal kingdom gives us striking examples of the importance of hearing,” explains Launer. A lot of people only realise how versatile our hearing is when they lose it. Hearing not only enables us to understand speech; our ears pick up countless important snippets of information from our environment that our brains process and filter for relevance. Hearing also conveys emotional states and signals danger.

The basic principle underlying hearing is the same for fish, reptiles, birds and mammals: sound starts as motion and is transformed into a stimulus by air. Most animals have acquired niche capabilities through the course of evolution, adapting their communication options according to their environment and climate. “When finches in the Andes move from the plains into the mountains, for example, they adapt the pitch and volume of their calls.” Compared to other mammals, humans have pretty good hearing. We are the best generalists, with a first-rate ability to differentiate fine nuances and perceive the widest range of frequencies. “In the natural world, humans are the decathletes, as it were, while animals are 100-metre specialists,” says Launer.

It is precisely this specialisation that makes the topic of hearing in the animal kingdom so interesting. A bat’s ultrasound sensing helps it hunt and find its bearings, while a number of animals – insects in particular – have long been object lessons for hearing researchers. Ormia ochracea is one such insect that has been showing the way. The fly is one of the most useful models for researchers seeking to perfect hearing instruments. There is a flexible rocker in the creature’s head that tips to one side as soon as it encounters a sound wave, and this principle is set to be applied to the next generation of hearing systems, although its technical feasibility remains to be seen. “We must always bear in mind how the animals make use of their systems; a principle that may work for a tiny fly may not transfer seamlessly to the larger and more complex human scale,” concludes Stefan Launer.

The animal kingdom is an exciting research field. There are animals with ears similar to yours or mine, animals with superhuman hearing – and even those that wear a hearing aid made by one of Sonova’s brands: specially trained search and rescue dogs, for instance. “As hearing loss sets in, fitting these animals with hearing aids is more effective than training up a new dog,” explains Launer. Other animals don’t enjoy the same benefits: “The spread of hearing loss in birds is a big problem, for example,” adds Launer. “It’s typically caused by increasing noise pollution in cities from building sites, traffic, etc.”

Sonova is a mine of information on the importance of hearing – not just for biology, but for business, science and as a reflection of social developments as well – and the first in a series of articles profiles the barn owl; under the heading “Did You Know?”, Sonova has been exploring a range of animals and demonstrating how relevant their hearing is for humans – from domestic pets, through exotic and endangered species, to the humble bee moth – with the intention of raising awareness and highlighting the importance of hearing and hearing loss.