For those who use a cochlear implant, also known as a bionic ear, public situations, where lots of people are talking over background noise, can be incredibly challenging.
In particular, honing in on a particular voice or voices with a babble of others in the background is very difficult, as the directional microphones in the implant aren’t overly successful at picking out distinct voices. This is known as ‘cocktail party situation’, according to Professor David Grayden, who might have found a solution to the problem.
Using the brain as a model, Grayden and his colleagues at the University of Melbourne have investigated into how humans process these conflicting noises.
In their findings, they discovered ‘octopus-shaped’ neurones that were perfect for identifying the puffs of air passing through our vocal chords, known as ‘glottal pulses.’
‘The key is that the ‘rhythms’ are different for different voices,’ Grayden explained. ‘The glottal pulses for different speakers will rarely occur at the same time, and the rate of these pulses will be different.’
Using a computer model, Grayden and his team were able to mimic a ‘cocktail party situation’ and found that a part of the brain called the ‘ventral nucleus of the lateral lemniscus’ (VNLL), was responsible for identifying when these ‘glottal pulses’ occurred so the other auditory neurones could focus on those sounds.
‘The brain uses the actual timing of glottal pulses as a cue to decide the most important time to listen,’ says Grayden and this is how the new implant could determine which voice to listen to.
Hopefully, these findings will lend to future bionic ear modifications and cocktail parties will become a bit easier for the wearers!
