Phonemic Restoration

Phonemic Restoration is a perceptual illusion in which a listener hears a phoneme (a speech sound) that is not actually present. Warren (1970; see also Warren & Obusek, 1971) first demonstrated the phenomenon experimentally by replacing the /s/ in "legislatures" with a cough or a tone. Listeners reported that they still heard the /s/, and they made mistakes when asked to say where the cough or tone had occurred in the word.

Samuel (1981)showed that phonemic restoration actually affects perceptual discriminability and not just response bias. Two types of stimuli were used: one in which noise replaced a phoneme in a word, and another in which noise was simply added on top of that phoneme. Samuel found that phonemic restoration made it more difficult for listeners to tell whether a phoneme was present with noise added or had been replaced by noise. In Signal Detection Theory terms, phonemic restoration reduced the discriminability between the two types of stimuli (as measured by d-prime).

The following .wav files demonstrate phonemic restoration. First the sentence "The soldier's thoughts of the battle made him nervous" was recorded and digitized. Next, a burst of white noise was created that completely overlapped with the phoneme /l/ in "battle." To created the added version of the sentence, the noise was superimposed on the sentence so that both the original word and the noise were present. To create the replaced version, the section of "battle" containing the phoneme /l/ was removed and the noise was inserted in its place.

Here is what the sentence with the phoneme /t/ removed sounds like:

And here is the noise by itself:

Now here is the sentence either with noise added to the /l/ in "battle" or with the /l/ removed and replaced with noise. Listen and try to guess which version it is, added or replaced:

Finally, here are both the added and replaced versions. Listen to the replaced version and see whether you hear the missing /l/ or not.


Samuel, A. G. (1981). Phonemic restoration: Insights from a new methodology. Journal of Experimental Psychology: General, 110:4, 474-494.

Warren, R. M. (1970). Perceptual restoratoin of missing speech sounds. Science, 167, 392-393.

Warren, R. M., & Obusek, C. (1971). Speech perception and phonemic restorations. Perception & Psychophysics, 9, 358-363.