Investigation of Auditory Objects Caused by Directional Sound Sources in Rooms

Abstract

The auditory impression of sound sources is strongly influenced by the room, which, e.g., determines the apparent source width. What is more, typical sources are not omnidirectional, which also makes their orientation a strong influence. This influence, however, has only been investigated a little, although it can even change the perceived location of the source. To provide more insight, we performed extensive listening experiments inside our anechoic laboratory that is equipped with a 24-channel loudspeaker playback to simulate both the directional source and the room. The directional source is described by two frequency-independent 3rd order directivity designs in 36 different orientations, and the room is simulated by the two-dimensional 1st and 2nd order image source method. Results of the experiment indicate that, in most cases, the auditory location can be determined by the loudest unmasked acoustic reflection path. This allows to explain the primary direction perceived with an astonishingly simple model including precedence effects.

Perceptual Matching of Room Acoustics for Auditory Augmented Reality in Small Rooms - Literature Review and Theoretical Framework

“…If the loudspeaker was turned by 180∘, facing away from the listener, the plausibility was seriously affected, if the same approach was used (Neidhardt, 2021). This confirms the findings by Zotter & Frank (2015); Steffens et al (2021) and shows that auralizations created by the various signal processing approaches should be tested with such an indirect reproduction scenario because it is much more critical than the listening positions in front of a sound source.…”

“…It was shown that these natural reflection properties result in a considerably different appearance of the precedence effect (Robinson et al, 2013; Wendt & Höldrich, 2021) and for surfaces in close distances (< 50 cm) additional near-field effects occur (Paasonen et al, 2017). Adding first-order image source reflections to a rotating directional sound source in a small room can lead to considerable shifts of the apparent source direction (Zotter & Frank, 2015). The addition of further reflections did not cause additional localization shifts, only smoothed the transition.…”

Compact Spherical Loudspeaker Arrays

“…Using a similar room simulation, the study in [21] asked participants to indicate the perceived direction of an auditory event created by a third-order directional source. The results showed that for different source orientations, listeners perceived auditory objects at directions that often did not coincide with the sound source, but with the delayed reflection paths, cf.…”

Evaluation of Three Auditory-Sculptural Qualities Created by an Icosahedral Loudspeaker

“…Laitinen [21] and Wendt [22] present experiments that use compact spherical beamformer arrays to vary distance impressions by crossfading between direct and indirect, rather diffuse sound reinforcement. In previous studies [23][24][25][26], we were able to show the basic characteristics of static and dynamic beamforming in various experiments using stationary and transient sounds. In a performance situation, a quarter-circle arrangement of reflectors is often employed to support a robust and detailed spatialization throughout the audience area [27], cf.…”