Figure 1.

Schematized spectrograms of induced and masked foregrounds. A single frequency tone is depicted as a horizontal bar with a narrow frequency range (A), but noise has a broader frequency spectrum (see Noise Only in D). Higher intensity components are represented by darker shading. A, A complete tone segment is reported as continuous by human listeners. B, A tone with a silent portion (gap) is reported as sounding discontinuous by listeners who readily detect the gap; however, when a higher intensity interrupting noise fills this gap (D), most listeners report that the tone was continuous throughout as if the tone were present in the noise (auditory induction). In this case they report that the stimulus in D sounds like the stimulus shown in C. E, When intense noise is changed to completely “surround” the foreground, the foreground is masked and continuity cannot be determined. Note, when lower intensity “surrounding” noise is used, no masking occurs, and the entire foreground is heard correctly. F, When a foreground with a gap is used with intense surrounding noise, the entire foreground is masked and continuity cannot be determined; however, with lower intensity noise, no masking occurs, and the discontinuity in the foreground can be readily identified. Note that there are intermediate intensities at which induction can occur without masking such that D would be reported as continuous and F would be reported as discontinuous.