Echoic memory, or auditory sensory memory, is part of the short-term memory and refers to the way the brain can take an exact copy of what is heard and hold it for very short periods, roughly two to four seconds. The term is credited to Ulric Neisser, and he is even better known for doing the foundational research on this form of remembering. Since Neisser’s work, additional studies on this type of memory continue to reveal new information about its functions.
When a person hears a sound, like a few notes of music or a short sentence, echoic memory engages and the brain keeps a perfect replica of that sound for a brief period. People may even defer paying attention to the sound’s meaning when they hear it, and could instead interpret the brain’s copy. For instance, sometimes a person isn’t paying full attention to another’s conversation. He might ask a speaker to repeat something, and then realize he knows what was said before the speaker can say it again. This is echoic memory in action, producing the copy of the sound so the person can catch up on listening or be able to briefly think about a sound’s significance.
Auditory short-term memory is often compared to visual or iconic memory. This is the brain’s ability to keep exact copies of an image. Comparatively, auditory sensory memory is much longer. Iconic memory lasts for less than a second, whereas echoic memory may reproduce a short sound for up to four seconds.
George Sperling performed the early studies on iconic memory in the 1960s. These became the blueprint for evaluating this type of memory. In 1967, Ulric Neisser designed similar tests and reporting strategies to those Sperling had used, in order to gain descriptive information about auditory sensory memory.
What Neisser discovered was that people might be able to exactly remember up to two seconds of auditory information. Additionally, each sound copy could exist for up to four seconds. Later, scientists had access to specialized brain scanning equipment and designed experiments to visualize the areas of the brain associated with echoic memory. The greatest activity during tests of this type was in the prefrontal cortex, which is where most other auditory signals are processed.
Other research into short-term auditory memory has shown that people appear to increase their echoic memory to higher second times as they grow. Therefore, a toddler’s auditory sensory memory isn’t as long as a teenager’s. Some of this ability to produce and keep copies of sounds tends to deteriorate with advanced aging, however.
Researchers are also focused on the implication of having an impaired echoic memory. The inability to retain copies of sounds for short periods has been linked to speech impairments. Individuals who lack this function may also suffer from a variety of communicative deficits.