Fig. 1.

Perceptual completion effects. a Examples of “modal” and “amodal” visual completion. In the modal case (left), we see a white rectangle overlaid on gray bars. However, the rectangle edges do not produce contrast where they overlap the background. In the amodal case (right), the black rectangle is seen to continue behind the gray bars. b Traditional examples of auditory completion. Tones can be heard to continue when interrupted with a sound (e.g., noise) sufficiently loud as to plausibly mask the tone. The tone is heard to continue even though it is not physically present during the noise. Illusory phonemes (or phonemic restoration) can also occur under similar conditions, when a short segment of speech is replaced with a louder sound. Here and in e, the gray shading of the sound waveform symbolizes illusory sound that is heard despite not being present in the stimulus. c Example auditory scene in which two sound sources (speech and applause) combine to form a single waveform that arrives at the ear. d Masking of background sound texture. The speech sound has more energy during certain time-frequency windows, intermittently masking the background applause sound. The red areas show windows where the speech has more energy than the applause. The blue areas show windows where the applause has more sound energy than the speech. e Illusory texture from auditory texture completion. Illusory texture can be heard when a texture is interrupted with another sound sufficiently loud as to mask the texture. The texture is heard to continue even though it is not physically present during the interrupting sound. Texture completion is differentiated from other forms of auditory completion in the long temporal extent over which illusory textures can be heard (often exceeding 2 s)