On one hand, you can’t hear while you’re sleeping. If someone tells you a secret while you’re asleep, unfortunately, you most likely won’t be able to “hear” and remember what they said. On the other hand, consider the use of an alarm to wake up. If you weren’t able to hear while you were sleeping, these devices wouldn’t serve to rouse you in the morning. With these two examples in mind, we can explore some of the gray areas between hearing and not hearing during sleep. The experts in audiology and sleep science can help us understand what is going on between hearing and sleeping, as well as why we can hear some things and not others.
Hearing and Listening
One of the ways to understand hearing ability during sleep is the distinction between hearing and listening. We are almost certainly unable to listen while we are asleep because listening requires devoted attention to sounds. When we focus on these sounds, we can process their meaning, and this inability during sleep means that we can’t necessarily remember a complex statement. If that were possible, just imagine the possibilities of listening to audiobooks or studying for tests! Although we can’t intentionally and consciously listen while asleep, we can hear quite a lot. Hearing includes the passive experience of processing sound, even in the unconscious parts of the mind. If you have ever found yourself humming a melody to a song that was playing in the background without realizing the song was there, you were likely hearing it without “listening.”
Sleep and Hearing Studies
Several studies help us understand the connection between sleep and hearing, particularly how much we can process, understand, and remember during sleep. One fascinating study engaged with the “cocktail party phenomenon.” The question is, why are you able to listen to one person in a crowded party and hear what they have to say, even if other voices are equally loud? Our brains are skilled at focusing on meaningful or interesting sound, and the same principle occurs during sleep. While a person was asleep, researchers played a sensical text in one ear, drawn from Wikipedia entries. In the other ear, they played a nonsensical combination of syllables called Jabberwocky. Using a technique called stimulus reconstruction, they were able to use brain imaging during sleep to discover that brains were processing sound from the meaningful ear rather than the ear listening to Jabberwocky.
This study helps us understand how it is possible to sleep through some disturbing sounds while also waking up to the sound of an alarm. Some people have the remarkable ability to sleep through anything, including sirens, alarms, and other distracting sounds. Remarkably, they can still wake up when they need to, sometimes by a relatively quiet alarm or buzzing phone. The cocktail party phenomenon helps us understand how this is possible. The brain can not only isolate sounds “of interest” while we are awake but also while we are asleep.
Though the sound of an alarm might need to be loud for some people, others can use the slightest sound to wake up. Some sounds even travel from the environment into our sleeping minds and dreams. If you’ve ever had a song, voice, or other sounds integrated with your dream, you can see that the connection between cognition, hearing, and sleep is quite complex.
More research can help us better understand what can and can’t be comprehended and retained during sleep. Many of the current studies have used a combination of brain imaging and interviews after the research subjects awaken. With advanced methods such as stimulus reconstruction, we can learn much more about sleep and hearing, as well as the way the brain processes sound while we are awake.
Many experts explain the ability to hear certain sounds “of interest” as an important protective mechanism of the mind, making it possible to awaken to the sound of one’s baby crying or a threatening sound that foretells danger while remaining asleep even in the loudest circumstances when rest is necessary. Without the ability to do both of these, we would be in danger or very tired!
Our sense of hearing is an important part of our overall health and well-being. Contact us today to schedule an appointment for a hearing test!