Perception, 2013, volume 42, pages 985 – 990

doi:10.1068/p7555

SHORT REPORT

Using acoustic information to perceive room size: effects of blindness, room reverberation time, and stimulus Andrew J Kolarik1, Shahina Pardhan2, Silvia Cirstea2, Brian C J Moore1 1 

Department of Psychology, University of Cambridge, Downing Street, Cambridge CB2 3EB, UK; e‑mail: [email protected]; 2  Vision and Eye Research Unit (VERU), Postgraduate Medical Institute, Anglia Ruskin University, Eastings 204, East Road, Cambridge CB1 1PT, UK Received 25 June 2013, in revised form 16 October 2013 Abstract. Blind participants greatly rely on sound for spatial information regarding the surrounding environment. It is not yet established whether lack of vision to calibrate audition in far space affects blind participants’ internal spatial representation of acoustic room size. Furthermore, blind participants may rely more on farthest distance estimates to sound sources compared with sighted participants when perceiving room size. Here we show that judgments of apparent room size and sound distance are correlated, more so for blind than for sighted participants. Sighted participants judged a reverberant virtual room to be larger for speech than for music or noise stimuli, whereas blind participants did not. The results suggest that blindness affects the use of room reverberation for distance and room-size judgments. Keywords: spatial hearing, blindness, auditory distance, room size

1 Background Acoustic cues provide information regarding sound source distance and room size. Although acoustic cues for room size afford much lower precision than visual cues (Calcagno et al 2012; Zahorik 2001), the former may be important to blind people, who rely on acoustic information for their spatial awareness of far space. Auditory distance information may also inform blind people when attempting to assess room dimensions; even in anechoic environments, blind people can use the perceived position of the farthest sound source to estimate the minimum possible distance to the far wall. Several authors have hypothesized that perceived auditory distance and perceived room size are related (Cabrera et al 2005; Calcagno et al 2012), and this hypothesis was tested here. We also tested whether lack of visual information to calibrate audition, previously shown to adversely affect some aspects of spatial hearing such as vertical sound localization (Lewald 2002), influenced acoustic room-size judgments. Finally, we tested whether perceived room size was affected by stimulus type and room reverberation characteristics. 2 Method Full details are given below. Groups of blind and sighted participants took part in the experiment. Virtualization methods were utilized to simulate sound sources at distances ranging from 1.22 to 13.79 m from the listener, in a large virtual room (see figure 1) that was either anechoic or reverberant. Stimuli consisted of speech, music, or a broadband 90 ms white noise burst. Participants reported the perceived distance of each sound for a series of trials with the same stimulus type, following which they were asked to estimate the perceived length, width, and height of the room.

986

A J Kolarik, S Pardhan, S Cirstea, B C J Moore

Virtual room size: 30 × 35 × 10 m

13.8 m

Figure 1. Schematic of the simulated room. The circle shows the participant’s position.

3 Results Figure 2 shows room-size estimates plotted as a function of farthest distance estimates. Two data points from the sighted group were removed as they fell more than three standard deviations away from the overall mean. Almost all responses were underestimates (actual room size = 10 500 m3, actual distance = 13.8 m). Correlation and orthogonal regression were used to examine the relationship between farthest distance estimates and room-volume estimates for the blind (solid lines) and sighted (dashed lines) groups. For the overall results, utilized for analysis to maximize experimental power, the correlation was higher for the blind than for the sighted group (r = 0.83, p 

Using acoustic information to perceive room size: effects of blindness, room reverberation time, and stimulus.

Blind participants greatly rely on sound for spatial information regarding the surrounding environment. It is not yet established whether lack of visi...
624KB Sizes 0 Downloads 0 Views