Auditory detection of multiple targets

When listeners focus on a single frequency to detect an auditory signal, other unattended sounds are suppressed and sensitivity to those sounds is diminished. If they focus on a sound with two or more frequency components, similar results are obtained, but sensitivity to each of the components is less than to a single frequency. The present paper shows just how signal detection is degraded when attention is directed by multi-component cues (comprising either two or four tones) to targets at various frequencies. Psychometric functions obtained with the multi-component cues are shifted toward higher signal levels (signals are first detected at higher levels) relative to those obtained in control conditions with a single-component cue. As the cue components are spread further apart in frequency, the shift in the psychometric function may become as large as 3dB; nevertheless, it is a generally smaller than the shift for a signal frequency that does not match any frequency component of the cue. Frequency spacing among the cue components also affects detection, with performance better (smaller shifts in the psychometric function) when the components are very far apart than when moderately far apart.