Know that noise? Scientists probe formation of auditory memories

Auditory perception requires the listener to learn recurring properties of complex sounds and associate them with plausible physical sources. “Most of our knowledge about auditory memory is based on simple sounds,” says lead study author Dr. Trevor Agus from the Ecole Normale Supérieure in Paris. “How templates emerge from everyday auditory experience with arbitrary complex sounds is currently largely unknown.”

Dr. Agus and colleagues used unpredictable, random hissing sounds, also known as noise, as a tool to observe the creation of new auditory memories in human listeners. Noise was particularly suitable for probing memory formation because the different sounds were acoustically complex, meaningless, and completely new to the listener.

Importantly, the listeners were unaware that identical copies of some of the noise samples would occasionally reoccur throughout the experiment.

The researchers discovered that repeated exposure induced learning for totally unpredictable and meaningless sounds. The listeners were better at detecting repetitions within noise samples that had been presented several times than new noise samples, showing that a new auditory memory had been created. “The sound memories were formed rapidly, with performance becoming abruptly near-perfect, and multiple noises were remembered for several weeks,” reports Dr. Agus.

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