Two identical sounds within 30–40 ms are fused into one located auditory event.

Evidence

The typical research scenario is shown in Figure 12.20, where two loudspeakers are placed in the azimuth directions of ±40◦in anechoic listening conditions. The lead sound event S0, typically with an impulsive sound, is presented at time instant 0 ms by the loudspeaker at 40◦, and an identical signal is presented as a lag sound event, ST, by the loudspeaker at −40◦. The delay τ between the sound events is varied. When τ is zero, the listener perceives a single sound event in front, and when τ is increased to about 1 ms, the single spatial auditory event migrates towards the lead sound event. The spatial perception remains the same until the onset of the echo threshold, which occurs for values of τ of about 30–40 ms, depending on the signal. Only after this threshold is crossed does the lag sound event create an additive, spatially separated auditory event. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1500

Categorization

• XREF: Connects to listener envelopment and precedence-effect material in earlier sound-perception chapters of this same book. — connects to: Two simultaneous pure tones may fuse rather than be heard separately.; Delayed identical sounds fuse into one source until a 30-40 ms echo threshold

Broader Connections

• Delayed identical sounds fuse into one source until a 30-40 ms echo threshold #corroborates (0.90)
• Two simultaneous pure tones may fuse rather than be heard separately. #expands (0.75)