Reverberation time and audibility in phased geometrical acoustics using plane or spherical wave reflection...

Area of Science:

• Room acoustics
• Architectural acoustics
• Acoustical modeling

Background:

• Geometrical acoustics is standard for large rooms; phased geometrical acoustics improves predictions for smaller spaces.
• Spherical wave reflection coefficients enhance accuracy, but their precise effect on room acoustics parameters requires further investigation.

Purpose of the Study:

• To predict reverberation time in medium-sized rooms (27-300 m³).
• To analyze the impact of spherical versus plane wave reflection modeling on reverberation time predictions.
• To assess the audibility of predicted differences through listening tests.

Main Methods:

• Phased geometrical acoustics was employed for reverberation time prediction.
• Plane and spherical wave reflection models were compared across various boundary conditions, including non-uniform absorption.
• Laboratory listening tests used narrow band noise stimuli (125 Hz, 250 Hz) and a three-alternative forced choice method.

Main Results:

• Calculated differences between plane and spherical wave models exceeded the 5% just-noticeable difference for reverberation time.
• Over half of the listeners could discern the modeled acoustic differences in all tested scenarios.
• Statistically significant differences were observed in two-thirds of cases, particularly those with longer reverberation times.

Conclusions:

• Spherical wave reflection modeling provides audibly distinct results compared to plane wave modeling in medium-sized rooms.
• The audibility of modeled differences is confirmed, especially in environments with longer reverberation.
• Phased geometrical acoustics with spherical wave considerations offers a more perceptually relevant approach to room acoustics prediction.