Effect of a single lateral diffuse reflection on spatial percepts and speech intelligibility.

Area of Science:

• Room acoustics
• Psychoacoustics
• Architectural acoustics

Background:

• Diffusive surfaces are common in room acoustics but their perceptual effects are not fully understood.
• Early lateral reflections significantly influence spatial perception and speech intelligibility.

Purpose of the Study:

• To investigate the perceptual and behavioral effects of diffuse versus specular reflections.
• To determine how reflection type, delay, and azimuth impact spatial percepts and speech intelligibility (SI).

Main Methods:

• Two experiments were conducted using field measurements and realistic acoustic elements.
• Compared diffuse and specular reflections with a speaker-like source directivity.
• Assessed spatial percepts (distance, width, focus) and SI in diffuse noise.

Main Results:

• A single diffuse reflection reduced perceived source distance and enhanced clarity.
• Speech intelligibility (SI) was significantly higher with diffuse reflections than specular ones.
• Perceptual outcomes were influenced by reflection angle, surface properties, and source directivity.

Conclusions:

• Diffuse reflections enhance speech clarity and intelligibility, contrary to specular reflections.
• Findings support the role of loudness, binaural cues, and the precedence effect in perception.
• Results provide valuable implications for optimizing acoustic design with diffusive surfaces.