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in Trimble Sketchup a . We normally model the audience area with a limited level of detail e.g. as a plane with skirts as this area is normally highly absorbing and scattering. In this room however in the unoccupied state the audience area consists of hard wooden chairs and desks. It was found that a model with a more detail audience area gave better agreements between simulations and measurements so the more detailed version of the audience area was included in this study. Initial materials were selected according to a visual inspection of the room and absorption coefficients were fine tuned in order to match average measured and simulated T 30 values. In this auditorium we examine: The influence of different signal to noise ratios on the obtained measurement results by using different sweep lengths. Whether meaningful measurement results can be obtained using different excitation signals (sweep, hand claps, popping balloons). The sensitivity to uncertainty of exact receiver position on measured and simulated parameters. Measured and simulated parameters for a number of receiver positions. Figure 4: Horizontal directivity pattern of the Dodecahedron Loudspeaker D12, by LANGE Loudspeakers, at 2000 and 4000 Hz. For the impulse response series obtained with ODEON a dodecahedron omni-directional source was employed. Figure 4 shows the directivity pattern for such a source by LANGE Loudspeakers b . It can be seen that at 2000 and 4000 Hz the source is not perfectly omnidirectional. a http://www.sketchup.com b http://www.langeloudspeakers.com 12
p x E-1 Impulse response recordings were made and processed with ODEON 12.1 for 2 sources (P) and 5 receiver (R) positions, giving a total of 10 combinations in accordance with the ISO 3382- 1 standard 3 . The following study is focused only on the results from source one (P1). A perspective view of the auditorium, together with a ground plan and the source-receiver positions is displayed in Figure 5. The impulse responses were recorded with an exponential sweep signal. Figure 6 shows an example of the impulse response for the combination S1-P1 at 4000 Hz. Room acoustic parameters described in ISO 3382-1 3 where derived. 0 3 5 8 10 13 metres 1 5 metres 3 P1 5 0 4 2 Odeon©1985-2013 Licensed to: Odeon Odeon©1985-2013 Licensed to: Odeon Figure 5: Model of the auditorium 21 at the Technical University of Denmark, as it appears inside ODEON. Left: Three-dimensional rendering of Auditorium 21 with colors corresponding to the reflectance of the surfaces 14 . Right: Source and receiver positions inside auditorium 21. D:\Measured Impulse responses\isra_measurements1\Auditorium21GEorgeClaus15feb2013\s1r1_4000.wav Ray Impulse response at 4000Hz 4 3.5 3 2.5 2 1.5 1 0.5 gfedcb gfedcb gfedcb Omni microphone Onset time Truncation time 0 -0.5 -1 -1.5 -2 -2.5 -3 -3.5 -4 -4.5 -0.2 -0.1 0 0.1 0.2 Odeon©1985-2013 Licensed to: Odeon A/S 0.3 0.4 0.5 0.6 0.7 0.8 time (seconds incl. filter delay) 0.9 1 1.1 1.2 1.3 Figure 6: Typical impulse response obtained with the sweep method in ODEON. Combination S1-R1 at 4000 Hz. 13
Page 1 and 2: Toronto, Canada International Sympo
Page 3 and 4: Table 1: Room Acoustic Parameters i
Page 5 and 6: scattering coefficients have been a
Page 7 and 8: prediction of C 80 it is important
Page 9 and 10: SPL(dB) can be some influence from
Page 11: is used for separating multiple imp
Page 15 and 16: SPL / Noise (dB) an indicator wheth
Page 17 and 18: Ts (ms) SPL (dB) Statistics Active
Page 19 and 20: 4.3 Different excitation stimuli Fo
Page 21 and 22: R3 at 4,55 m R2 at 6,84 m R5 at 8,9
Page 23 and 24: In Figure 16 measured and simulated
Page 25 and 26: 6 CONCLUSIONS It is possible to mak

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