Informational masking and auditory attention.
Informational masking is broadly defined as a degradation of auditory detection or discrimination of a signal embedded in a context of other similar sounds; it is not related to energetic masking caused by physical interactions between signal and masker. In this paper, we report a systematic release from informational masking of a target tone in a nine-tone rapid auditory sequence as the target is increasingly isolated in frequency or intensity from the remaining sequence components. Improved target-tone frequency difference limens as isolation increases are interpreted as a reflection of increasingly focused auditory attention. The change from diffuse to highly focused attention is gradual over the frequency and intensity ranges examined, with each 1-dB increment in target intensity relative to the remaining components producing performance improvements equivalent to those produced by a 2% increase in frequency isolation. The results are modeled as bands of attention in the frequency and intensity domains. For attention directed by frequency isolation, there is a strong correspondence with auditory filters predicted by the power spectrum model of masking. These data also support the existence of an attention band of intensity, with a bandwidth of about 5-7 dB at the moderate levels used in this experiment.
Leek
M R
MR
Army Audiology and Speech Center, Walter Reed Army Medical Center, Washington, DC 20307-5001.
Brown
M E
ME
Dorman
M F
MF
D000328:Adult; D001288:Attention; D006801:Humans; D008144:Loudness Perception; D010470:Perceptual Masking; D010897:Pitch Discrimination; D011571:Psychoacoustics; D013018:Sound Spectrography