AUDITORY VERSUS VISUAL SPATIAL IMPRESSION: A STUDY OF TWO .
Proceedings of ICAD 04-Tenth Meeting of the International Conference on Auditory Display, Sydney, Australia, July 6-9, 2004AUDITORY VERSUS VISUAL SPATIAL IMPRESSION:A STUDY OF TWO AUDITORIADensil Cabrera, Andy Nguyen and Young Ji ChoiSchool of Architecture, Design Science and PlanningThe University of SydneyNSW 2006, Australiadensil@arch.usyd.edu.auABSTRACTSpatial impression refers to the attributes of subjective spacebeyond localization. In the field of auditorium acoustics,auditory spatial impression is often divided into ‘apparentsource width’, ‘envelopment’ and sometimes ‘intimacy’. Inseparate experiments, this study considers how visual andauditory spatial impression vary within two auditoria, and hencesimilarities between these two sensory modes.In the visual experiment, the ‘spaciousness’, ‘envelopment’,‘stage dominance’, ‘intimacy’ and target distance were judgedby subjects using grayscale projected photographs, taken fromvarious positions in the audience areas of the two auditoriawhen a visual target was on stage.In the auditory experiment, the ‘apparent source width’,‘envelopment’, ‘intimacy’ and performer distance were judgedusing an anechoic orchestral recording convolved with binauralimpulse responses measured from the same positions in the twoauditoria.Results show target distance to be of primary importance inauditory and visual spatial impression – thereby providing abasis for covariance between some attributes of auditory andvisual spatial impression. Nevertheless, some attributes ofspatial impression diverge between the senses.1.INTRODUCTIONFor many years, researchers the field of auditorium acousticshave been interested in the auditory spatial impression ofauditoria, and its variation within an auditorium. Auditoryspatial impression contributes much to the judged acousticalquality of soundfields for music [1]. Three of the mostcommonly studied spatial attributes are apparent source width(commonly abbreviated to ASW), listener envelopment (LEV)and intimacy, with a high level of each of these being desirablefor musical acoustics [1].ASW, an aspect of the more general term ‘spaciousness’, isused to assess the effect of an auditorium environment on theauditory image size of a musical performance. Strong earlylateral reflections are among the factors that can contribute tolarge ASW. Although ASW disregards expansion in dimensionsother than width, width is thought to be the most significantexpansion dimension, because of the horizontal separationbetween the two ears. The absolute maximum interaural crosscorrelation coefficient (IACC) taken from the first 80 ms of abinaural impulse response is often used as a predictor of ASW.LEV refers to the sense of being surrounded that isengendered by a reverberant field. While ASW is affectedprimarily by the spatial impulse response 0-80 ms after thedirect sound, LEV is primarily affected by the late sound, after80 ms. The strength of the late lateral sound energy is animportant predictor of LEV. IACC can also be used to predictLEV, although late lateral sound level measures are moreeffective.Intimacy is a sense of closeness to and involvement with aperformance – as opposed to a sense of detachment. The abilityto discern detail is likely to be important for intimacy. Whilesome researchers relate intimacy to the delay between the directsound and the first significant reflection in the impulse response[2], this relationship may be of limited application [3].Perceived distance is not normally considered directly inauditory spatial impression in the auditorium acoustics field,but could plausibly be related to intimacy. In rooms, perceiveddistance depends on multiple cues, such as sound pressurelevel, frequency content, familiarity with the source, and theratio of direct to reverberant sound energy [4]. In auditorydistance estimation experiments, there is a tendency forunderestimation, especially in the far field – and there may be acontext-dependent horizon beyond which all sound sources areheard as equally distant.Beyond auditorium acoustics, auditory spatial impressionhas been studied in audio systems. Soulodre et al [5] havefound that physical acoustic correlates of LEV apply to spatialaudio reproduction in much the same way as in auditoriumcontexts. Rumsey [6] has identified dimensions of spatial audioreproduction, drawing partly on the auditorium acousticstradition, as well as audio quality listening tests. His keyattributes are grouped into those concerned with width, depthand immersion. The concepts of width, depth and immersionare applied to individual sound sources, the ensemble, and theenvironment. In fact the model is rather more complex thandescribed here, its complexity suggesting that the threepreviously mentioned attributes of ASW, LEV and intimacyscarcely account for the variety of impressions available inspatial hearing, especially if contexts beyond auditoriumacoustics are considered.The study of visual space appears not to offer aconcentrated body of work on spatial impression equivalent tothat offered by auditorium acoustics. The approach of this paperis to apply visual spatial impression scales based on the threeauditory spatial impression scales of ASW, LEV and intimacy.ASW may not be simply related to an aspect of visualexperience, because the visually perceived boundaries of imagestend to be better defined than those of auditory images. In anauditorium context, the concept of ‘stage dominance’ could be arough visual counterpart of ASW – if the stage is to be thoughtof as the visual target. The term ‘spaciousness’, which is often
Proceedings of ICAD 04-Tenth Meeting of the International Conference on Auditory Display, Sydney, Australia, July 6-9, 2004closely related to ASW in the auditorium acoustics literature,pertains more to the perception of a room’s field of view invision [7, 8, 9] rather than the space occupied by performers.The perceived size of a space depends on the size of the visualsolid angle and apparent depth of the visual image. Perspectiveis a cue for depth [9], and the balance of surfaces across visualimages is controlled by room form (such as width and height).Envelopment, in the visual world, is a feeling of beingsurrounded by objects, surface, people, light, and more. Inphenomenological writings, envelopment refers to one’s bodyin the center with the experiential world surrounding [10, 11].According to this theory, we experience the world not onlythrough vision, but also through the body. This seems tosuggest that ‘envelopment’ seems to translate well betweenmodes of experience, such as auditory, olfactory, andkinesthetics [12]. Roundness in an architectural space appearsto encourage this sense of surroundedness. Darkness – or thedepletion of visual perception – may also provide a sense ofenvelopment as the person relies on senses closer to the body[13].Intimacy, in the visual world, relates to distance orproximity of the body to the surrounding visual elements suchas surfaces, objects, or people. Visual intimacy is alsoassociated with the ability to see clearly facial details or surfacetextures [12].Visual distance cues include monocular accommodationand binocular convergence, perspective, knowledge of thetarget (especially its size), retinal image size of boundaries andtextures, and many more [7, 8, 9, 14]. There is some evidencefor progressive underestimation of visual distances withincreasing physical distance, which may be analogous to theunderestimation of auditory distances previously mentioned [8,15].Nguyen and Cabrera studied the visual spatial impression ofthree auditoria (two of which are represented in the presentstudy) [16]. Subjects (professional architects) made judgementsof grayscale photographs using the terms ‘spaciousness’,‘envelopment’, ‘stage dominance’ and ‘intimacy’, and thesubjects also estimated the performer distance. That studyfound performer distance to be judged rather accurately acrossthe range from 10 m to 45 m, with a tendency to underestimate.Spaciousness was close to the inverse of intimacy, both being afunction of distance from the visual target on the stage.Envelopment was not affected by distance, but instead wasaffected by the auditorium. Stage dominance was affected bydistance and auditorium. However, that study mixed imagesfrom the three auditoria in the experiment, thereby focussing thesubjects’ attention on differences between the auditoria. In thepresent study subjects assess one auditorium at a time, and sothe emphasis is on differences in spatial impression within eachauditorium.2.AIMThis study compares the auditory and visual spatial impressionin representations of two auditoria. As a case study, itinvestigates the degree of commonality between auditory andvisual spatial impression in each auditorium. If matchingattributes of spatial impression in the two senses co-vary, thenthere is some prospect for sensory substitution in applicationssuch as auditory display.Figure 1. Photographs from the rear gallery of Hall A(top) and Hall B (bottom).3.METHOD3.1. AuditoriaThe two auditoria that were tested contrasted in severalways. Hall A (the Michael Fowler Centre in Wellington, NewZealand) is a large volume concert and multipurposeauditorium. Hall B (the Verbrugghen Hall at the University ofSydney’s Conservatorium of Music) is of moderate volume,primarily designed for music recital. Physical characteristics ofthese auditoria are summarized in Table 1.Hall AHall BVolume25,000 m37650 m3ShapeEllipticRectangularMaximum Length42 m34 mMaximum Width36 m18 mMaximum Height22 m12.5 mStage Area (when visited)100 m2235 m2Seats2,500450Table 1: Physical characteristics of Hall A and B.Note that the stage area in Hall B, which occupies 40% ofthe main floor area, is substantially larger than that of Hall A.The Hall A stage was in its smallest configuration when visited,
Proceedings of ICAD 04-Tenth Meeting of the International Conference on Auditory Display, Sydney, Australia, July 6-9, 2004with choral risers replacing the rear of the stage, and withoutthe front stage extension.Both visual and auditory spatial impression were explicitconsiderations in the design of Hall A [17].3.2. Auditory ExperimentBinaural impulse responses were measured in both halls using aBrüel & Kjær Head and Torso Simulator (HATS), and aloudspeaker in the center of the stage. The HATS ears were at aheight of 1.2 m above the floor, and the loudspeaker at a heightof 1.4 m, in the center of the stage. In Hall A, a Mackie HR824loudspeaker was used as the measurement source, whilst aSoundsphere 2212-1 loudspeaker on a custom-built subwooferwas used in Hall B [18]. The loudspeaker for Hall A is a studiomonitor, while the system in Hall B is closer to omnidirectional,more powerful, and covers a broader frequency range (logisticsprecluded taking this system to New Zealand). In bothauditoria, impulse responses were obtained from logarithmicsine sweeps (60 Hz – 18 kHz, 60 s in Hall A; and 20 Hz –20 kHz, 5.4 s in Hall B). Hall A had 15 receiver position(galleries and stalls), while Hall B had 9 (stalls only) – refer toTable 2. These responses were extracted and analyzed usingAurora software [19], yielding 2.5 to 3.5 seconds of impulseresponse 6W34W08AA25BB35HH44D12D17D7I12I19I5M21M3N10Table 2:stimuli.Angle fromGalleryDistanceMidlineor StallsfromSourceA12 m60 GalleryA13.5 m35 GalleryA20 m35 GalleryA20 m25 GalleryA20 m10 GalleryA25 m0 GalleryA10 m0 StallsA15 m0 StallsA15 m15 StallsA20 m15 StallsA20 m0 StallsA22 m45 StallsA25 m25 StallsA25 m25 StallsA30 m15 StallsB10 m0 StallsB10 m15 StallsB10 m15 StallsB15 m0 StallsB15 m15 StallsB15 m15 StallsB20 m15 StallsB20 m15 StallsB20 m0 StallsMeasurement positions represented by the auditoryHallMeasurements were calibrated, so that the sensitivity of thetwo ear channels could be matched, and the variation in soundpressure level through each auditorium could maintained.However, the measurement system level between auditoriacould not be matched meaningfully due to the differentloudspeaker systems used.An anechoic recording of the opening 15 seconds of theOverture to the Marriage of Figaro (Mozart) [20] wasconvolved with the measured impulse responses to create thesubjective experiment auditory stimuli. As this experiment usedSennheiser HD600 headphones, the transfer function betweenthese headphones and the HATS ear simulators wascompensated for through 1/3-octave band digital equalization.Subjects listened to the stimuli in an anechoic room usingheadphones. Although anechoic conditions were not required,the low noise floor of this room (of 18 dBA) was presumed tobe important in allowing subjects to hear the sometimes subtledifferences between the sound stimuli. A black curtain coveredthe absorptive wall in front of the subjects so as to reduce visualdistraction.The 13 subjects (researchers and students in acoustics andaudio) were mostly already familiar with the concepts of spatialimpression such as ASW, LEV and intimacy. Nevertheless,these were defined and explained to them and illustratedgraphically to ensure that they responded meaningfully to thescales. Stimuli representing the two auditoria were presented indifferent sessions, so as to emphasize sensitivities to differenceswithin each hall. Subjects listened to all stimuli for anauditorium before beginning their assessment of thatauditorium. For each auditorium, four audio compact discs wereprepared containing all stimuli, in distinct randomly determinedorder. Subjects listened to one of these discs for training, andanother for the experiment. Half the subjects assessed Hall Afirst, and the other assessed Hall B first. Thus stimulus orderwas systematically varied between subjects, such that no twosubjects had the same overall stimulus order.ASW, LEV and intimacy were rated on a discrete integerscale ranging between 0 (defined as ‘none’) and 10 (defined as‘maximal’). Source distance was estimated in meters.Table 3 summarizes the characteristics of the auditorystimuli, either in terms of the impulse response properties orbinaural measurements of the actual stimuli. Unless otherwisestated, values are for mid frequencies (500 Hz and 1 kHz octaveband mean). Low frequency values (mean of 125 Hz and250 Hz octave bands) and high frequency values (mean of2 kHz and 4 kHz octave bands) were also included in theanalysis, as well as other kinds of acoustical measurement.Exponential means are used for decibels, and standarddeviations are parenthesized.Hall AHall BReverberation Time RT302.3 s (0.05)2.2 s (0.04)Early Decay Time1.7 s (0.24)2.3 s (0.09)Clarity Index C502.7 dB (1.1)-6.5 dB (1.3)Clarity Index C804.5 dB (1.3)-3.5 dB (1.0)IACC0.28 (0.09)0.21 (0.09)Broadband SPL76 dB (1.8)79 dB (1.3)Table 3: Acoustical characteristics of the auditory stimuli. IACCis the early inter-aural cross-correlation coefficient [1], and SPLis the equivalent sound pressure level (Leq) measured at themicrophones of a dummy head wearing the headphones used inthe experiment.3.3. Visual ExperimentGrayscale images were taken at a height of 1.2 m at selectedseat positions, with a music stand and chair on the stage at thecenter of the frame (at the same location as the loudspeaker ofthe auditory experiment). Camera locations were the same asthe dummy head locations of the auditory experiment, exceptthat additional photographs were taken in Hall B, mainly in itsgallery (no impulse responses had been recorded in the Hall Bgallery for logistical reasons). A Nikon Coolpix 5400 digital
Proceedings of ICAD 04-Tenth Meeting of the International Conference on Auditory Display, Sydney, Australia, July 6-9, 2004camera was used with a lens focal length equivalent to 28 mm(with respect to a 35 mm film camera). Typical minimalperformance lighting conditions were used. Fifteen imageswere taken in each hall. The additional positions used forphotographs in Hall B are summarized in Table 4.Angle fromGalleryDistanceMidlineor StallsfromSourceO5B20 m10 StallsO10*B20 m0 StallsGR3B10 m45 GalleryGR15B25 m15 GalleryGA10B20 m0 GalleryGC10B22 m0 GalleryGE10B25 m0 GalleryTable 4: Additional measurement positions used in the visualbut not the auditory experiment. Seat O10 was used instead ofN10 in the visual experiment (these seats are both close to 20 mfrom the source, on the auditorium’s midline).SeatNumberHallThe images were presented via a data projector, with theimage size approximately 1.5 m across in a small windowlessroom. There were 13 subjects, 10 of whom had not participatedin the auditory test. The distance between the subjects and thescreen was from 2 to 3 m. The lights were dimmed in the room.The tests were presented using Microsoft PowerPoint,automatically changing the slides in a timed sequence. Theybegan with a preview section, which allowed the subjects to seeall 15 images for a hall. The first image was projected for 60 s,each subsequent image having a 2 s reduction, hence the lasthaving a duration of 32 s. The two halls were presented inseparate slide-shows, so as to emphasize sensitivity todifferences between images within each hall. Image order wasrandomly varied between sessions.For each image, subjects rated the Sense of Spaciousness(defined as the apparent volume of the room, as perceived fromthe image); the Sense of Envelopment (defined as the sense ofbeing surrounded by the three-dimensional space); the StageSpatial Dominance (defined as the degree to which the stagedominates the image); the Sense of Intimacy (defined as theapparent proximity or closeness to the performer); and theestimated distance from the camera to the performer (in meters).The first four subjective parameters were rated using a discretescale (from 0 to 10, where 0 was defined as ‘none’, and 10 as‘maximal’).Table 5 summarizes some characteristics of the images usedin the experiment. Note that some images in the stalls of Hall Ascarcely had a view of the stage surface due to their angle ofview.Hall AHall BImage Brightness78 (16)91 (8)Stage Brightness213 (30)173 (17)Non-stage Brightness75 (18)81 (14)Stage:Non-stage area ratio0.02 (0.02)0.12 (0.12)Table 5: Image characteristics. Brightness is stated as an 8-bitnumber (ranging from 0-255).4.RESULTSAs the two auditoria were tested in separate sessions in both theauditory and visual experiments, they are separated in theanalysis (although they are charted together in the figures).Analysis of variance (ANOVA, factorial) was used to test thesignificance of differences in subjective ratings for the singleindependent variable of Seat Number. ANOVA showssignificance in both auditoria for the auditory scales of LEV andIntimacy and the visual scales of Spaciousness, StageDominance, Intimacy and Estimated Distance. Non-significantauditory results were obtained in the Hall A for ASW (P 0.15)and the ratio of perceived to actual distance (P 0.09). A nonsignificant visual envelopment result was obtained in Hall A(P 0.12).4.1. Distance EstimatesDespite their lack of significance (which reflects a wide spreadof responses) auditory distance results show some systematicrelationships with distance in both auditoria (Figure 2). Usingtrim means (upper and lower quartiles excluded), the stall seatsin Hall A match actual distance well (r 0.87, P 0.001), whilstthe gallery seats lack such a relationship. In Hall B, distancesare overestimated, but still correlate to actual distance (r 0.70,P 0.03). The differences in responses between the twoauditoria appear to be partly due to the greater bass levelachieved in Hall B, which gave the impression of a larger room(based on informal feedback given by the subjects). The use ofan omnidirectional source in Hall B is also likely to haveincreased its distance estimates by giving a lower direct-toreverberant sound energy ratio than a directional source. Thiscontrast may have been increased both by the fact that Hall Awas designed for great clarity [17], and that the smaller volumeof Hall B for a
auditory spatial impression is often divided into ‘apparent source width’, ‘envelopment’ and sometimes ‘intimacy’. In separate experiments, this study considers how visual and auditory spatial impression vary within two auditoria, and hence similarities between these two sensory modes.
Complete denture impression Impression Trays In complete denture prosthesis we make two impressions for each patient: a primary impression and final or secondary impression. To make an impression we should have impression tray. Impression tray: it is a device used to carry, confine and control the impression material from the patient's mouth while making an impression. During impression making .
tray impression for a fixed complete denture. The impression copings for a closed tray technique are placed on implants or multi-unit abutments and the impression made. The impression material polymerizes the impression is dislodged from the closed tray impression copings. Furthermore, the impression copings are removed and implant
Test of Auditory Comprehension of Language-3. Austin, TX: PRO-ED. Test of Auditory Processing Skills, 3rd Edition (TAPS-3): This test measures what the person does with what is heard, and can be used for ages 4-18. There are numerous sub scores, and three cluster scores including basic auditory skills, auditory memory, and auditory cohesion.
Impression making is an essential step in the fabrication of complete dentures. The success of complete dentures depends on selecting the impression materials , the accuracy of the impression and the impression technique. Impression mak-ing in total edentulism is important, not only for denture retention and stability but also for the mucosa status, which should be maintained without any .
healthcare services. Complete dentures are one of the treatment modalities for edentulous patients [1] [2]. Impression making is an essential step in the fabrication of complete dentures. The success of complete dentures depends on selecting the impression materials , the accuracy of the impression and the impression technique. Impression mak-
and auditory perceptual parallel processing effect in the brain. On this account, auditory sentence materials were presented that varied in syntax (syntactically correct vs. syntactically incorrect) and auditory space (standard vs. infrequent ITD change). For the source analysis, a distributed source model was used without any priors regarding the
social development. Visual processing refers to a group of skills used for interpreting and understanding visual information. The evaluation may include testing for visual spatial orientation skills, visual analysis skills, including auditory-visual integration, visual-motor integration skills and rapid naming.
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