Carvajal, Juan Camilo Gil

Cubick, Jens

Dau, Torsten

Santurette, Sébastien

Sounds presented via headphones are typically perceived inside the head. However, the illusion of a sound source located out in space away from the listener’s head can be generated with binaural headphone-based auralization systems by convolving anechoic sound signals with a binaural room impulse response (BRIR) measured with miniature microphones placed in the listener’s ear canals. Sound externalization of such virtual sounds can be very convincing and robust but there have been reports that the illusion might break down when the listening environment differs from the room in which the BRIRs were recorded [1,2,3]. This may be due to incongruent auditory cues between the recording and playback room during sound reproduction [2]. Alternatively, an expectation effect caused by the visual impression of the room may affect the position of the perceived auditory image [3]. Here, we systematically investigated whether incongruent auditory and visual roomrelated cues affected sound externalization in terms of perceived distance, azimuthal localization, and compactness

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Downloaded from orbit.dtu.dk on: Dec 21, 2017Effects of incongruent auditory and visual room-related cues on sound externalizationCarvajal, Juan Camilo Gil; Santurette, Sébastien; Cubick, Jens; Dau, TorstenPublication date:2015Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Carvajal, J. C. G., Santurette, S., Cubick, J., & Dau, T. (2015). Effects of incongruent auditory and visual room-related cues on sound externalization. Poster session presented at Tenth anniversary symposium of theinternational laboratory for Brain, Music, and Sound Research, Montréal, Canada.Effects of incongruent auditory and visualroom-related cues on sound externalizationJuan Camilo Gil Carvajal, Sébastien Santurette, Jens Cubick, Torsten DauHearing Systems, Department of Electrical Engineering, Technical University of DenmarkIntroductionSounds presented via headphones are typically perceivedinside the head. However, the illusion of a sound sourcelocated out in space away from the listener’s head canbe generated with binaural headphone-based auralizationsystems by convolving anechoic sound signals with a bin-aural room impulse response (BRIR) measured with minia-ture microphones placed in the listener’s ear canals. Soundexternalization of such virtual sounds can be very convinc-ing and robust but there have been reports that the illusionmight break down when the listening environment differsfrom the room in which the BRIRs were recorded [1,2,3].This may be due to incongruent auditory cues betweenthe recording and playback room during sound reproduc-tion [2]. Alternatively, an expectation effect caused by thevisual impression of the room may affect the position of theperceived auditory image [3]. Here, we systematically in-vestigated whether incongruent auditory and visual room-related cues affected sound externalization in terms of per-ceived distance, azimuthal localization, and compactness.Methods• Eighteen naïve listeners were divided into two groups:– A: Blindfolded during testing but with auditory aware-ness of the room provided by an in-room noise source– V: Shielded from room-related acoustic input but withvisual awareness of the room• All listeners also tested with all cues (VA) available• Three playback rooms:– IECM: Medium-sized IEC standard (V ≈ 100 m3, T60 =0.4 s) in which all BRIRs were recorded– RevS: Small reverberant (V = 43.2 m3, T60 = 2.8 s)– DryL: Large anechoic (V = 330.4 m3, T60 < 0.01 s)Fig.1 Overview of the experimental procedure followed by test subjects.• Seven azimuthal positions (2, 3, 6, 7, 9, 11, and 12o’clock) were reproduced• Loudspeakers visible at positions 1, 3, 11, and 12• Subjective rating scales for distance, azimuth, and com-pactness perceptionFig.2 Loudspeaker setup and subjective rating scales used for the experiments.For distance judgments, listeners could provide ratings of 0 (inside the head), 1,2, 3, 4 (at the loudspeaker), or 5, corresponding to areas I, II, III, IV, V, and VI, re-spectively. For compactness judgments, listeners could provide ratings of 0 (mostcompact), 1, 2, 3, 4, or 5 (least compact), corresponding to areas A, B, C, D, E, andF, respectively.Results: Distance perception. IECM RevS DryLVAAVFig.3 Distance perception ratings obtained in the three playback rooms under conditions VA, A, and V for each tested source position. The boxplots indicate median valuesacross subjects as well as first and third quartiles. ‘Ref’ stands for a dry diotic reference signal, ‘All’ for the median rating across all source positions.• Significant effect of listening environment: lower VA ratings in RevS for all positions, in DryL for positions 3, 6, 11, and 12• In RevS, no difference between A and VA conditions, but significantly higher ratings for V than VA for most positions• In DryL, no significant differences between A, V, and VA conditions for most positionsResults: Azimuthal localization. 2 o’clock 6 o’clock 12 o’clock 2 o’clockFig.4 Angular orientation ratings obtained for positions2, 6, and 12 in room IECM . Top row: A vs VA. Bottom row:V vs VA. Upper right panel: VA in different rooms.• No significant effect of listening room:Similar confusions in all rooms• Visual capturing effect: Less correctresponses at position 2 for V vs VA andfor VA vs A• Less front-back confusions for VA vs AResults: Compactness• No significant ef-fect of listening en-vironment: Similarratings in all rooms• Similar but lessconsistent ratingswhen cues fromeither modality arelimitedFig.5 Compactness ratings obtained in condition VA in the three playback rooms.References:[1] Begault DR (1999). “Auditory and non-auditory factors that potentially influ-ence virtual acoustic imagery,” Proc. Audio Eng. Soc. 16:13-26.[2] Werner S, Siegel A (2011). “Effects of binaural auralization via headphones onthe perception of acoustic scenes,” Proc. ISAAR 3:215-222.[3] Udesen J, Piechowiak T, Gran F (2015). “The effect of vision on psychoacoustictesting with headphone-based virtual sound,” J. Audio Eng. Soc. 63:552-561.Conclusions• A mismatch between recording and playback room isdetrimental to virtual sound externalization.• The auditory modality governs externalization in termsof perceived distance when cues from the recording andplayback room are incongruent.• In incongruent listening situations, the more reverber-ant the playback room is, the more critical the auditoryimpression of the room becomes.• The visual impression of the room does not affect per-ceived distance, but source-related visual cues help re-solve localization ambiguities and improve compactnessperception.Presented at: Tenth Anniversary Symposium of the International Laboratory forBrain, Music, and Sound Research — October 22, 2015, Montréal, CanadaContact: Juan Camilo Gil Carvajal — s130655@student.dtu.dkSébastien Santurette — ses@elektro.dtu.dkJens Cubick — jecu@elektro.dtu.dkTorsten Dau — tdau@elektro.dtu.dk

Effects of incongruent auditory and visual room-related cues on sound externalization

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Effects of incongruent auditory and visual room-related cues on sound externalization

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