How does the human brain memorize a sound?

Jun 03, 2010

Sound repetition allows us to memorize complex sounds in a very quick, effective and durable way. This form of auditory learning, which was evidenced for the first time by French researchers from CNRS, ENS Paris, and Paris Descartes and Toulouse universities, is believed to occur in daily life to help us identify and memorize sound patterns; it allows, for example, immediate recognition of sounds which become familiar through experience, such as the voice of relatives.

The same mechanism is involved in the relearning of certain sounds, in particular when using hearing aids. This study, which has just been published in the journal Neuron, opens new perspectives for understanding the process of auditory memory.

“Until now, the only available data on acoustic memorization concerned simple sounds or language”, points out Daniel Pressnitzer. Three French researchers set themselves the challenge of addressing complex sounds and studying our ability to memorize them, as little was known on the subject.

In order to investigate how auditory memory is formed, the researchers subjected volunteers to various noise samples: these noises were generated in a totally random and unpredictable way to ensure that the volunteers would never have heard them before. Furthermore, these original complex had no meaning, and were perceived at first as an indistinct hiss. Listeners were not told that an identical complex noise pattern could be played several times during the experiment.

Using this fairly simple protocol, the scientists discovered that our ear is remarkably effective in detecting noise repetitions. Listeners nearly always recognized the noise pattern that had been played several times; two listenings were enough for those with a trained ear, and only about ten for less experienced ears. Sound repetition therefore induces both extremely rapid and effective learning, which occurs implicitly (it is not supervised). In addition, this memory for noise can last several weeks. A fortnight after the first experiment, volunteers identified the noise pattern again, at first attempt.

The scientists have demonstrated the existence of a form of fast, solid and long-lasting auditory learning. Their experimental protocol has proven to be a relevant and simple method that could make it possible to study auditory memory in both humans and animals. These results imply that a mechanism for rapid auditory plasticity - that is, a mechanism involved in an auditory neuron's ability to adapt its response to a given sound stimulant - plays a very effective role in the learning of sounds. This process is likely to be essential to identify and memorize recurrent sound patterns in our acoustic environment, such as the voice of relatives. It has all the characteristics considered necessary for human beings to learn to associate a with what produces it.

The same mechanism may also be involved in relearning, which is often inevitable when hearing suddenly changes. This is true of hearing-impaired people who start using hearing aids. A period of adaptation to their prosthesis is necessary so they can get used to hearing sounds they no longer heard or perceived differently. The researchers hope that one day they will be able to study the effect of the modifications introduced by hearing aids on re-learning more in depth.

Explore further: 'Trigger' for stress processes discovered in the brain

More information: Sound illustrations: audition.ens.fr/memonoise/

Rapid formation of robust auditory memories: Insights from noise. Trevor R. Agus, Simon J. Thorpe, Daniel Pressnitzer. Neuron. May 27, 2010.

add to favorites email to friend print save as pdf

Related Stories

Lend me your ears -- and the world will sound very different

Jan 14, 2008

Recognising people, objects or animals by the sound they make is an important survival skill and something most of us take for granted. But very similar objects can physically make very dissimilar sounds and we are able to ...

Brain center for 'sound space' identified

Sep 19, 2007

While the visual regions of the brain have been intensively mapped, many important regions for auditory processing remain terra incognita. Now, researchers have identified the region responsible for a key auditory process—perceiving ...

Study shows Human Sounds may Kill Fish

Mar 12, 2009

(PhysOrg.com) -- Anthropogenic, or human generated, sounds have the potential to significantly affect the lives of aquatic animals - from the individual animal’s well-being, right through to its reproduction, migration ...

Recommended for you

'Chatty' cells help build the brain

10 hours ago

The cerebral cortex, which controls higher processes such as perception, thought and cognition, is the most complex structure in the mammalian central nervous system. Although much is known about the intricate ...

'Trigger' for stress processes discovered in the brain

Nov 27, 2014

At the Center for Brain Research at the MedUni Vienna an important factor for stress has been identified in collaboration with the Karolinska Institutet in Stockholm (Sweden). This is the protein secretagogin ...

New research supporting stroke rehabilitation

Nov 26, 2014

Using world-leading research methods, the team of Dr David Wright and Prof Paul Holmes, working with Dr Jacqueline Williams from the Victoria University in Melbourne, studied activity in an area of the brain ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.