Effect of spatial separation between traffic noise and water sound on soundscape assessment

This study aims to examine the effect of the spatial separation and signal-to-noise ratio (SNR) between target traffic noise and water sound on soundscape assessment. An in situ audio-visual recording of a water fountain was augmented with an audio recording of a busy expressway for the laboratory test. The combined acoustic stimuli (traffic noise and water sound) were generated at five azimuths: water sound co-located with the traffic (0°) or symmetrically separated by ±45°, ±90°, ±135°, or 180°. In addition, the water sound presented at two SNRs (-3 and 3 dB). For audio-visual congruency, the viewpoint of the fountain video in each stimulus was shifted by the same azimuths (location of traffic is fixed). Participants experienced the audio-visual stimuli through a multi-channel loudspeaker system and a head-mounted display. The participants were asked to evaluate the perceived loudness of noise and overall soundscape quality of each stimulus. Results revealed that the effect of azimuth separation was significant in both perceived loudness of noise and overall soundscape quality. Meanwhile, the effect of SNR was only significant on the perceived loudness of noise.