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Investigating sound decrement per doubling of distance as a universal room acoustics parameter Ng, Denny
Abstract
The suitability of Sound Decay per Doubling of Distance (π·πΏβ), as a universal room acoustics rating parameter was investigated. π·πΏβ was combined with the Speech Transmission Index (πππΌ) to rate acoustical room quality. This follows the methodology of ISO 3382-3, allowing evaluation of room quality using speech intelligibility as a foundation quantity. To prescribe rating criteria, all rooms where unamplified speech is present were postulated to be categorizable into one of three room types: Case 1 (intelligibility) rooms where intelligibility is required at all distances, Case 2 (distraction) rooms where distraction is permissible until a defined distance, or Case 3 (privacy) rooms where privacy is expected beyond a defined distance. For rating metrics, Case 1 used listening effort, Case 2 used loss of productivity, and Case 3 used percentage of speech intelligible. An idealized initial tool was developed which calculates πππΌ at all points along a π·πΏβ curve. The tool calculated πππΌ based only on reverberant speech and was therefore applicable only to rooms where direct speech is impeded by obstacles. Assumptions used in the initial tool were checked using experimental data collected in 62 rooms of varying case classifications from 22 buildings. The data were used to evaluate the accuracy of regressions using sound pressure level measurements over a limited range of 1 β 16 m (π·πΏ2,π ,π΄,1β16π,), the octave band variation in π·πΏ2, and the sound pressure level at 1 m from a sound source. The maximum regression error for π·πΏ2,π ,π΄,1β16π, was 5.6 dB, and 2.5 dB on average. DL2 trends observed in the experimental data were then implemented in the DL2 tool and the STI calculation model was updated to include direct speech contributions. The updated tool was used to evaluate theoretical rooms for each case using the developed rating schemes. Room reverberation time (RT, π) and background noise levels (BNL, πΏπ) were modeled using values recommended in standards. Due to the variability of RT and BNL within rooms of similar types, standardized rating schemes based on π·πΏβ were deemed unfeasible. However, π·πΏβ and the tool developed provide valuable insight on how to optimize rooms acoustically.
Item Metadata
Title |
Investigating sound decrement per doubling of distance as a universal room acoustics parameter
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2020
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Description |
The suitability of Sound Decay per Doubling of Distance (π·πΏβ), as a universal room acoustics rating parameter was investigated.
π·πΏβ was combined with the Speech Transmission Index (πππΌ) to rate acoustical room quality. This follows the methodology of ISO 3382-3, allowing evaluation of room quality using speech intelligibility as a foundation quantity.
To prescribe rating criteria, all rooms where unamplified speech is present were postulated to be categorizable into one of three room types: Case 1 (intelligibility) rooms where intelligibility is required at all distances, Case 2 (distraction) rooms where distraction is permissible until a defined distance, or Case 3 (privacy) rooms where privacy is expected beyond a defined distance. For rating metrics, Case 1 used listening effort, Case 2 used loss of productivity, and Case 3 used percentage of speech intelligible.
An idealized initial tool was developed which calculates πππΌ at all points along a π·πΏβ curve. The tool calculated πππΌ based only on reverberant speech and was therefore applicable only to rooms where direct speech is impeded by obstacles.
Assumptions used in the initial tool were checked using experimental data collected in 62 rooms of varying case classifications from 22 buildings. The data were used to evaluate the accuracy of regressions using sound pressure level measurements over a limited range of 1 β 16 m (π·πΏ2,π ,π΄,1β16π,), the octave band variation in π·πΏ2, and the sound pressure level at 1 m from a sound source. The maximum regression error for π·πΏ2,π ,π΄,1β16π, was 5.6 dB, and 2.5 dB on average.
DL2 trends observed in the experimental data were then implemented in the DL2 tool and the STI calculation model was updated to include direct speech contributions.
The updated tool was used to evaluate theoretical rooms for each case using the developed rating schemes. Room reverberation time (RT, π) and background noise levels (BNL, πΏπ) were modeled using values recommended in standards.
Due to the variability of RT and BNL within rooms of similar types, standardized rating schemes based on π·πΏβ were deemed unfeasible. However, π·πΏβ and the tool developed provide valuable insight on how to optimize rooms acoustically.
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Genre | |
Type | |
Language |
eng
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Date Available |
2020-02-20
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0388674
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2020-05
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Campus | |
Scholarly Level |
Graduate
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Rights URI | |
Aggregated Source Repository |
DSpace
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Rights
Attribution-NonCommercial-NoDerivatives 4.0 International