Phonemic restoration effect

This effect is commonly observed in a conversation with heavy background noise, making it difficult to properly hear every phoneme being spoken.

Different factors can change the strength of the effect, including how rich the context or linguistic cues are in speech, as well as the listener's state, such as their hearing status or age.

The purpose of the experiment was to give a reason to why in background of extraneous sounds, masked individual phonemes were still comprehensible.

In his initial experiments, Warren provided the sentence shown and first replaced the first 's' phoneme in legislatures with extraneous noise, in the form of a cough.

Phonemic restoration is one of several phenomena demonstrating that prior, existing knowledge in the brain provides it with tools to attempt a guess at missing information, something in principle similar to an optical illusion.

It is believed that humans and other vertebrates have evolved the ability to complete acoustic signals that are critical but communicated under naturally noisy conditions.

For humans, while it is not fully known at what point in the processing hierarchy the phonemic restoration effect occurs,[3] evidence points to dynamic restorative processes already occurring with basic modulations of sound set at natural articulation rates.

[4] Recent research using direct neurophysiological recordings from human epilepsy patients implanted with electrodes over auditory and language cortex has shown that the lateral superior temporal gyrus (STG; a core part of Wernicke's area) represents the missing sound that listeners perceive.

This research is also dependent on the amount of words the observer is comfortable understanding because of the nature of top-down processing.

[12] Female as opposed to male listeners were better able to use a delayed informative cue at the end of a long sentence to report an earlier word which was disrupted by noise.

The additional produced white noise that replaces the phoneme adds its own echo and causes listeners to not perform as well.

Because the brain processes information optimally at a certain rate, when the gap became approximately the length of the word is when the effect started top breakdown and become ineffective.

Using the visual cues of mouth movements, the brain will you both in top-down processing to make a decision about what phoneme is supposed to be heard.

[16][17] Only when the intensity of the noise replacing the phonemes is the same or louder as the surrounding words, does the effect properly work.

This version of the phonemic restoration effect was particularly strong because the brain was doing much less guess work with the sentence, because the information was given to the observer.