Echoic memory is the sensory memory that register specific to auditory information (sounds). Once an auditory stimulus is heard, it is stored in memory so that it can be processed and understood.Unlike visual memory, in which our eyes can scan the stimuli over and over, the auditory stimuli cannot be scanned over and over. Since echoic memories are heard once, they are stored for slightly longer periods of time than iconic memories (visual memories). Auditory stimuli are received by the ear one at a time before they can be processed and understood. For instance, hearing the radio is very different from reading a magazine. A person can only hear the radio once at a given time, while the magazine can be read over and over again. It can be said that the echoic memory is like a "holding tank" concept, because a sound is unprocessed (or held back) until the following sound is heard, and only then can it be made meaningful.This particular sensory store is capable of storing large amounts of auditory information that is only retained for a short period of time (3–4 seconds). This echoic sound resonates in the mind and is replayed for this brief amount of time shortly after being heard. Echoic memory encodes only moderately primitive aspects of the stimuli, for example pitch, which specifies localization to the non-association brain regions.

TESTING METHODS

Partial and whole report

Following Sperling's (1960) procedures on iconic memory tasks, future researchers were interested in testing the same phenomenon for the auditory sensory store. Echoic memory is measured by behavioural tasks where participants are asked to repeat a sequence of tones, words, or syllables that were presented to them, usually requiring attention and motivation. The most famous partial report task was conducted by presenting participants with an auditory stimulus in the left, right, and both ears simultaneously.Then they were asked to report spatial location and category name of each stimulus. Results showed that spatial location was far easier to recall than semantic information when inhibiting information from one ear over the other. Consistent with results on iconic memory tasks, performance on the partial report conditions were far superior to the whole report condition. In addition, a decrease in performance was observed as the interstimulus interval (length of time between presentation of the stimulus and recall) increased.

Auditory backward recognition masking

Auditory backward recognition masking is one of the most successful tasks in studying audition. It involves presenting participants with a brief target stimulus, followed by a second stimulus (the mask) after an interstimulus interval. The amount of time the auditory information is available in memory is manipulated by the length of the interstimulus interval. Performance as indicated by accuracy of target information increases as the interstimulus interval increased to 250 ms. The mask doesn't affect the amount of information obtained from the stimulus, but it acts as interference for further processing.

Mismatch negativity

A more objective, independent task capable of measuring auditory sensory memory that does not require focused attention are mismatch negativity tasks, which record changes in activation in the brain by use of electroencephalography. This records elements of auditory event-related potentials of brain activity elicited 150-200ms after a stimulus. This stimulus is an unattended, infrequent, "oddball" or deviant stimulus presented among a sequence of standard stimuli, thereby comparing the deviant stimulus to a memory trace.

PROMBLEMS

Children with deficits in auditory memory have been shown to have developmental language disorders.These problems are difficult to assess since performance could be due to their inability to understand a given task, rather than a problem with their memory.

People with attributed unilateral damage to the dorsolateral prefrontal cortex and temporal-parietal cortex after experiencing a stroke were measured using the mismatch negativity test. For the control group the mismatch negativity amplitude was largest in the right hemisphere regardless if the tone was presented in the right or left ear.

Mismatch negativity was greatly reduced for temporal-parietal damaged patients when the auditory stimulus was presented to the contralateral ear of the lesion side of the brain. This adheres to the theory of auditory sensory memory being stored in the contralateral auditory cortex of ear presentation.Further research on stroke victims with a reduced auditory memory store has shown that listening to daily music or audio books improved their echoic memory. This shows a positive effect of music in neural rehabilitation after brain damage