A recent discovery explains how we have it brain It handles conversations in noisy environments and could have a significant impact on the development of more efficient hearing aids.
Vinay Raghavan, a researcher at Columbia University in New York, offers an interesting explanation of how the brain processes speech perception. According to him, the prevailing idea was that only the voice of the person we pay attention to is processed by the brain.
However, Raghavan questions this notion, stating that when someone is screaming in a crowded place, we don’t ignore it even when we focus on someone else.
Experts are looking at how the human brain processes sounds
During the controlled study by Vinay Raghavan and his team, electrodes were attached to the brains of seven individuals during epileptic seizures, allowing brain activity to be monitored.
During this procedure, participants were exposed to a 30-minute audio clip with two sounds superimposed.
Participants were kept awake during the surgery and their attention was directed to alternate between the two sounds in the sound. One of the voices was a man’s voice, the other a woman’s.
The overlapping voices spoke simultaneously, at similar volumes, but at certain times in the clip one voice was louder than the other, mimicking the difference in volumes found in background conversations in crowded environments.
The research team used data obtained from the participants’ brain activity to develop a model that predicts how the brain processes sounds of different sizes and how this might vary depending on which sound the participants were trained to focus on.
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The results revealed that the two higher volumes were encoded both in the primary auditory cortex, which is responsible for the conscious perception of sound, and in the secondary auditory cortex, which is responsible for processing the more complex sound.
This result was surprising, as the participants were instructed not to focus on the loudest sound, yet the brain processed this information in a meaningful way.
According to Raghavan, this study is groundbreaking in showing, through neuroscience, that the brain encodes speech information even when we’re not actively paying attention to it.
This discovery opens a new way to understand how the brain processes stimuli to which we do not direct our attention.
Traditionally, it has been believed that the brain selectively processes only those stimuli that we consciously focus on. However, the results of this study challenge this view, showing that the brain continues to encode information even when we are distracted or engaged in other tasks.
The results also revealed that the lower sound was only processed by the brain in the primary and secondary cortex when the participants were instructed to focus their attention on that specific sound.
Moreover, surprisingly, it took the brain an additional 95 milliseconds to process this sound as speech compared to the time participants were asked to focus on the loudest sound.
Still according to Vinay Raghavan, the results of the study show that the brain probably uses different controls to encode and represent sounds at different volumes during a conversation. This understanding can be applied in developing more effective hearing aids.
The expert suggests that if a hearing aid can be created that is able to identify the person the user is paying attention to, then it would be possible to increase the volume of only that specific person.
A breakthrough of this caliber can greatly improve the listening experience in noisy environments, allowing the user to better focus on the sound source of interest.
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