Pitch strength, tone segregation, and frequency difference limen.

For pure tones in narrowband noise, two percepts are considered. At a sufficiently high tone-to-noise ratio, the tone can be clearly distinguished from the noise: the tone and the noise segregate. At a low signal-to-noise (SN) ratio, slightly above the masking threshold, only a tonal noise is perceived: the tone is fused with the narrowband noise. With respect to these phenomena, two hypotheses are tested relating pitch strength, tone segregation, and frequency difference limen. The first hypothesis is that with the aforementioned stimuli, pitch strength alone is capable to serve as a segregation cue. The second hypothesis tested is that frequency difference limen is the psychophysical correlate of this sensation. Three experiments were conducted. The first experiment was an identification experiment. Listeners had to identify a segregated tone at five center-frequencies (250-4000 Hz, octave-wise) in the presence of narrowband noise. The second experiment measured the detection threshold of the tone. The third experiment determined the frequency difference limen at various SN ratios. The results suggest that not only pitch strength can serve as segregation cue but is tied to the frequency resolvability.