Echo thresholds for reflections from acoustically diffusive architectural surfaces

Area of Science:

• Acoustics
• Psychoacoustics
• Architectural Acoustics

Background:

• Sound reflection from irregular surfaces causes temporal and spatial diffusion.
• Research has focused on predicting diffusion, with less attention to its perceptual impact.
• Differences in reflection waveforms (damped onset/offset, spread energy, lower amplitude, decorrelation) from architectural surfaces are significant but perceptually undocumented.

Purpose of the Study:

• To investigate the perceptual effect of temporal diffusion on the echo threshold.
• To compare the detectability of diffuse reflections versus specular reflections.

Main Methods:

• Echo threshold tests were performed using speech and music signals.
• Simulated reflections with varying degrees of temporal diffusion were compared to direct sound and specular reflections.
• Stimuli were presented in diotic and spatialized formats.

Main Results:

• Diffuse reflections were less detectable as separate auditory events than specular reflections for speech signals at equal energy.
• No significant difference in echo threshold was found for music signals between diffuse and specular reflections.
• Echo thresholds were shorter for speech than music, and for spatialized than diotic presentation.

Conclusions:

• Temporal diffusion significantly impacts the detectability of reflections in speech, making them less perceptible as echoes.
• The perceptual effect of temporal diffusion on echo threshold differs between speech and music signals.
• Auditory presentation methods (diotic vs. spatialized) and signal type influence echo threshold perception.