05_Quirt_COST2011-Zurich_Impact

Objective and Subjective Assessment of
Response of Floor Assemblies to
Footstep & Low-Frequency Impact Sounds
David Quirt, presenting the findings of
B. Gover, J. Bradley, B. Zeitler, and S. Schoenwald
Dave.Quirt@nrc-cnrc.gc.ca
Presented at COST TU0901, Zurich, November 2011
Impact Sound in Buildings
 Created by occupants:
walking, jumping, etc.
 Recognized need for
subjectively relevant
ratings (metrics)
 Research project
investigating design
details for lightweight
wood construction (in
part for Japanese and
Korean markets)
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Direct
Transmission
Flanking
Transmission
Flanking
Transmission
Impact Sources and Metrics
Metrics
Standard
tapping
machine
 Ln,w (ISO 717)
 Ln,w+CI,100-2500 (ISO 717)
 Ln,w+CI,50-2500 (ISO 717)
Metrics
Impact ball
 Li,Fmax,r (JIS A 1419)
 Li,Fmax,Aw (KS F 2863)
 LiFavg,Fmax (63-1kHz) (Ryu et al.)
Metrics
Tire “bang”
machine
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 Li,Fmax,r (JIS A 1419)
 Li,Fmax,Aw (KS F 2863)
 LiFavg,Fmax (63-1kHz) (Ryu et al.)
The Approach
 Physical measurements of
assemblies in laboratory,
using sources and ratings
defined in ISO, ASTM, JIS,
KS standards.
 Recordings of impact
sounds gathered for
laboratory playback and
subjective judgment
 Subjective judgments and
rankings compared with
standardized and nonstandardized metrics
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Recordings for Subjective Evaluation
Ball drop at centre of floor
(from 10, 50, 100 cm height)
Ceiling
(bottom of
assembly)
Adult without shoes
walking in circular pattern
1.2 m
Added
absorption
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Subjective Tests
 Recorded impact sounds
played to listeners in room
(loudspeakers above ceiling)
 Listeners rated annoyance
compared to reference case
Recordings
from assembly X
Playback
 12 subjects, 19 assemblies
?
Judgment?
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Results:
Children run & jump
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Adult walkers
Results: Impacts simulating children
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Results: Adults walking (no shoes)
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Results: Two Sources
 Different sources yield different rankings
 So… do we need to add a “heavy-soft” test method?
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Results: Conventional Measures
 Good correlations of subjective judgement with ratings from
measurements using standard tapping machine
 Adding spectrum adaptation term CI improves the correlation
 Not a surprise – Warnock showed strong correlation of floor
attenuation for hammer box, walkers, heavy/soft impactors
 But Ln,w +CI (50-2500) may not be the best choice for other
sources such as walkers with hard shoes or dropping dishes
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Conclusions & Ongoing Work
 Good correlations of subjective judgement with ratings
from measurements using standard tapping machine
(for both sock-footed walkers and ball drop sounds
simulating running children)
 Inclusion of spectrum adaptation term CI improves the
correlation for Ln,w
 Other weighting choices may be even better,
considering all the significant sources expected
 Listening tests and analysis continue
Acknowledgements: Canada Wood Group; Council of Forest
Industries; Forestry Innovation Investment British Columbia;
Natural Resources Canada
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