Could more noise mean better hearing?
Could more noise mean better hearing? lead image
Mechanical ventilators are better at moving air when they include some amount of randomness in their pumping. This is not the only strange benefit of randomness: adding noise to signals can boost transmission in a phenomenon known as stochastic facilitation or stochastic resonance.
For cochlear implant users, this counterintuitive idea has the potential to improve hearing. The human cochlea contains approximately 30,000 nerve fibers, each of which produces about 60 completely random nerve spikes per second. With cochlear implants, there is instead a clean slate. This poses the question: should we add noise to mimic the random signals produced by cochlear nerve fibers, or would it be better to keep the implants noise-free?
Morse et al. investigated this query, finding the amount of transmitted information increased overall after adding noise to a cochlear implant signal.
The team sent electrical signals, corresponding to five different vowel sounds, to one electrode within the cochlear implant and noise to the other electrodes. They asked 12 participants to categorize the vowels. In addition to measuring the percent sorted correctly, they explored how much information the listeners obtained from each vowel formant, or energy peak at a certain frequency.
“Adding the noise increased the amount of information that was transmitted, but we didn’t see an increase in their ability to actually identify the vowels,” said author Robert Morse.
This means the participants grouped the vowels together correctly, but without prolonged training often miscategorized which specific vowel they were hearing.
While these preliminary results suggest adding noise may be beneficial for cochlear implant users, further studies are needed with more patients to see how the concept could be implemented in practice.
Source: “Noise helps cochlear implant listeners to categorize vowels,” by Robert P. Morse, Stephen D. Holmes, Richard Irving, and David McAlpine, JASA Express Letters (2022). The article can be accessed at https://doi.org/10.1121/10.0010071 .
