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Achieving acoustical comfort in restaurants

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Abstract

The achievement of a proper acoustical ambiance for restaurants has long been described as a problem of controlling noise to allow for speech intelligibility among patrons at the same table. This simplification of the acoustical design problem for restaurants does not entirely result in achieving either a sensation of acoustical comfort or a preferred condition for social activity sought by architects. In order to more fully study the subjective impression of acoustical comfort a large data base from 11 restaurants with 75 patron surveys for each (825 total) was assembled for analysis. The results indicate that a specific narrow range of reverberation time can produce acoustical comfort for restaurant patrons of all ages. Other physical and acoustical conditions of the dining space are shown to have little to no consistent effect on the registration of comfort. The results also indicate that different subjective components of acoustical comfort – quietude, communication, privacy – vary significantly by age group with specific consequences for the acoustical design of restaurants for different clienteles.
Published by the Acoustical Society of America
Volume 22 http://acousticalsociety.org/
168th Meeting of the Acoustical Society of America
Indianapolis, Indiana
27-31 October 2014
Architectural Acoustics: Paper 3pAA2
Achieving acoustical comfort in restaurants
Paul L. Battaglia, AIA
Department of Architecture, University at Buffalo, Buffalo, NY; plb@buffalo.edu
The achievement of a proper acoustical ambiance for restaurants has long been described as a
problem of controlling noise to allow for speech intelligibility among patrons at the same table.
This simplification of the acoustical design problem for restaurants does not entirely result in
achieving either a sensation of acoustical comfort or a preferred condition for social activity
sought by architects. In order to more fully study the subjective impression of acoustical comfort
a large data base from 11 restaurants with 75 patron surveys for each (825 total) was assembled
for analysis. The results indicate that a specific narrow range of reverberation time can produce
acoustical comfort for restaurant patrons of all ages. Other physical and acoustical conditions of
the dining space are shown to have little to no consistent effect on the registration of comfort.
The results also indicate that different subjective components of acoustical comfort quietude,
communication, privacy vary significantly by age group with specific consequences for the
acoustical design of restaurants for different clienteles.
© 2015 Acoustical Society of America [DOI: 10.1121/2.0000019]
Received 01 January 2015; Published 29 January 2015
Proceedings of Meetings on Acoustics, Vol. 22, 015001 (2015)
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Introduction
This study utilizes a compilation of data from students’ final pro jects for a spring 2014 seminar
conducted in the Department of Architecture, University at Buffalo. The seminar was entitled
“Aural Architecture” from a book by Brian Blesser and Linda-Ruth Salter and thus investigated
what they defined as “the properties of a space that can be experienced by listenin g.”1
In preparation for the final project students read and presented reports on recently-published papers
covering the study of acoustics in restaurants. Papers included a study by Astolfi and Fillippi that
found that good speech intelligibility by people at their own tables as well as speech privacy from
people at adjacent tables could be achieved through control of reverberation, absorption and
seating density.2Nahid and Hodgson reported from their study that optimal conditions for verbal-
communication quality could be achieved with a reduction in spatial volume, the use of physical
barriers and absorptive treatments.3
Of particular interest was a paper by Jens Holger Rindel which seeks to define acoustical qualit y
in restaurants.4Rindel developed a formula from his study:
Nmax = V/20 T.
This relationship defines the recommended maximum quantity of persons (N max) for sufficient
quality of verbal communication in terms of the cubic volume V (m3) and the reverberation time
T (seconds). When the Sabine equation for reverberation time, T = .16 V/a, is substituted into
Rindel’s formula we found that it reduces to:
Nmax = 0.3 a
Rindel’s paper continued to define acoustical quality according to the ratio of actual patrons (C,
for capacity) to the recommended maximum number of persons for sufficient quality of verbal
communication (C/Nmax). Since a ratio less than 1 represents good quality, this ratio was inverted
by the class so that a higher value indicates higher quality (Q) such that:
Q = Nmax /C = 0.3 a/C
Rindel’s measure of acoustical quality is directly proportional to the total amount of sound
absorption divided by the total number of occupants . This value (a/C) is identified as “ap
(absorption per person) for inclusion in the analysis with other more common acoustical and
physical measures of the subject spaces.
The Restaurants
The students each selected three restaurants from a list prepared by the author. They contacted the
owners to describe the project and to request permission to conduct the study including distribution
of a patron survey. As they encountered some resistance to the survey, some needed more than
three choices to find a willing participant.
Eventually, 17 restaurants were identified by the class (one for each student). Studies were
completed and final reports submitted. For this compilation six of the restaurant reports produced
by the students were eliminated for a variety of reasons of unsuitability of the locations for study.
Restaurant No. 12 had four separate dining spaces, each with diff erent acoustical conditions; the
P. Battaglia
Achieving acoustical comfort in restaurants
Proceedings of Meetings on Acoustics, Vol. 22, 015001 (2015)
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returned surveys were undifferentiated as to their
source space. Restaurants Nos. 13 and 14 a
Japanese noodle bar and a Chinese fast-food venue
had cooking areas within the dining space with
very loud (>82 dBC) exhaust fans in range hoods.
Restaurant No. 15 had large windows fronting a
busy street, with the glass about 5 meters from the
curb, resulting in a loud, intermittent background
noise. Restaurants Nos. 16 and 17 – a large dining
hall in a dormitory and a student center dining
lounge had surveys returned from only young
diners, almost entirely under 25 years of age. The
remaining 11 restaurants, quite fortunately,
represent a large range of sizes, acoustical
conditions, and ages of diners, and no extraneous
noise.
The Survey
A patron survey was prepared by the class for
distribution by waiters at each of the study
locations (Fig. 1). Managers were directed to give
willing patrons the survey only during times when
the restaurant was busy, notably 75% full or more.
(We trust this directive was followed but do not
have verification in all cases).
The survey includes only six questions. One
identifies the patron’s age grouping and a second
the frequency of dining at the restaurant, intended
as an indication of comfort. The second question
does not necessarily indicate
acoustic
comfort as
the class would decide, so only the age group
question was included in data analysis. The other
four questions ranked subjective impressions on a
scale from 1 to 4 for Quietude, Communication,
Privacy, and Comfort. These four questions were
presented so that a higher response value indicates
that the restaurant appears to be quiet (Quietude);
that it is easy to have a conversation with other
diners at the table (Communication, assumed to be
related to sound level, not personality or the
content of the conversation); that the conversations
from adjacent tables are not disturbing (Privacy);
and that, overall, the restaurant’s acoustic
environment subjectively appears “comfortable”
Figure 1: Patron Survey
P. Battaglia
Achieving acoustical comfort in restaurants
Proceedings of Meetings on Acoustics, Vol. 22, 015001 (2015)
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for whatever aural conditions the patron would associate with the term (Comfort).
The survey data would have benefited from a question regarding Preference: “Do you like the way
this restaurant sounds?” Also, some measure of Capacity during the survey might improve
verification of the results: “Right now, about how full is this restaurant?
The Data
The students read one of nine different papers selected by the author from acoustic journals and
presented them (in pairs) to the entire seminar. These papers were discussed by the class and
information from each was used to identify several acoustical and physical characteristics of spaces
whose measures might define the acoustical quality of restaurants . These characteristics were
combined with the survey results to create the data set (Fig. 2).
Restaurant No.
1
2
3
4
5
6
7
8
9
10
11
Acoustic
Measures
T: Reverberation Time (sec)
0.367
0.458
0.517
0.530
0.711
0.748
0.769
0.825
1.188
1.467
1.518
B: Background Noise (dBC)
72
78
72
72
82
78
80
73
84
70
81
Basic
Measures
L: Length (m)
23.7
11.9
16.7
26.6
17.1
16.3
9.2
10.7
16.8
18.6
13.9
W: Width (m)
9.6
9.7
8.4
11.2
9.7
5.5
7.3
10.0
15.2
11.6
13.4
H: Height (m)
3.0
3.1
3.3
2.4
4.6
4.0
3.0
3.6
4.1
6.1
4.6
C: Capacity (persons)
152
96
70
100
133
60
60
50
210
100
96
Calculated
Measures
F: Floor Area (m2)
228
115
140
298
166
90
67
107
255
216
186
V: Volume (m3)
684
356
462
715
764
360
201
385
1,045
1,316
856
D: Density-1 (m2/person)
1.50
1.20
2.00
2.98
1.25
1.50
1.12
2.14
1.21
2.16
1.94
P: Proportions (Cavity Ratio)
2.20
2.90
2.95
1.52
3.72
4.86
3.69
3.48
2.57
4.27
3.37
R: Ratio (Aspect Ratio)
2.47
1.23
1.99
2.38
1.76
2.96
1.26
1.07
1.11
1.60
1.04
aT: Absorption, Total (m2)
298
124
143
216
172
77
42
75
141
144
90
aP: Absorption per Person
1.96
1.29
2.04
2.16
1.29
1.28
0.70
1.50
0.67
1.44
0.94
Average
Demographics
Age Group
2.480
2.507
2.940
1.933
1.827
2.534
2.160
2.400
1.851
1.630
2.200
Visits
2.452
3.213
2.490
2.547
2.267
2.702
1.880
2.980
2.014
3.560
2.520
Average
Subjective
Impressions
Quietude
2.667
2.853
2.930
2.960
2.687
2.982
2.610
2.820
1.486
2.300
2.240
Communication
2.947
3.213
3.440
3.187
3.280
3.517
2.626
3.300
2.270
2.960
2.440
Privacy
3.013
3.473
3.440
3.107
3.267
3.466
2.800
3.340
2.757
2.760
2.400
Comfort
3.240
3.320
3.440
3.373
3.160
3.534
2.933
3.370
2.919
2.800
2.360
Age Group 1:
25 and under
Quietude
2.833
2.938
2.500
2.824
2.778
2.667
2.067
2.750
1.367
2.432
2.571
Communication
3.278
3.188
4.000
3.088
3.500
3.833
3.000
3.750
2.433
3.023
2.714
Privacy
3.389
3.500
3.500
2.912
3.306
3.667
2.933
4.000
2.767
2.841
2.714
Comfort
3.444
3.375
4.000
3.324
3.556
3.667
3.133
3.875
3.067
2.864
2.714
Age Group 2:
26 to 45
Quietude
2.875
2.857
3.000
3.111
3.114
3.217
2.243
2.647
1.741
2.158
2.600
Communication
3.000
3.381
3.077
3.167
3.500
3.609
2.595
3.088
2.407
3.053
2.800
Privacy
3.000
3.524
3.077
3.333
3.455
3.522
2.919
3.147
2.852
2.684
2.600
Comfort
3.500
3.524
3.308
3.444
3.136
3.652
3.027
3.294
3.185
2.842
2.600
Age Group 3:
46 to 65
Quietude
2.607
2.857
2.935
3.176
2.182
2.700
2.579
3.071
1.333
2.250
1.833
Communication
2.893
3.381
3.478
3.412
2.818
3.350
2.526
3.536
1.733
2.625
2.333
Privacy
3.000
3.524
3.543
3.176
2.909
3.350
2.684
3.393
2.600
2.625
2.333
Comfort
3.107
3.524
3.413
3.294
2.818
3.400
2.737
3.500
2.333
2.500
2.167
Age Group 4:
66 and over
Quietude
2.308
2.933
3.000
2.667
1.500
3.333
2.500
2.800
1.000
1.500
NA
Communication
2.538
3.000
3.615
3.167
2.000
3.444
2.000
3.200
2.000
2.500
NA
Privacy
2.538
3.267
3.538
3.333
3.000
3.444
1.750
3.200
2.500
2.500
NA
Comfort
2.923
3.000
3.615
3.667
1.500
3.444
2.250
3.200
1.500
2.250
NA
Figure 2: Restaurant Data
The basic acoustical measure of Reverberation Time (RT-60 at 1,000 Hz) was measured when
unoccupied utilizing free online software (Room Equalization Wizard v.5). Background Noise
(dBC) was measured for each restaurant when more than 75% occupied, during the dinner hour,
P. Battaglia
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Proceedings of Meetings on Acoustics, Vol. 22, 015001 (2015)
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utilizing a Radio Shack sound level meter in the
center of the space and averaging readings over
two minutes. Basic physical measures of Length,
Width and Height were developed by drawing
three-dimensional models of the space and using
the model to define a rectangular solid of equal
area and volume. Capacity was determined by a
count of seats, including stools at the bar where it
was part of the same space as the dining area.
The basic dimensions that were collected and
documented in the drawings were used to
calculate the physical measures that might affect
subjective impressions of acoustical comfort.
Floor Area, Cubic Volume, Cavity Ratio (5H x
(L+W)/LW), Aspect Ratio (L/W), Total
Absorption, the measure of Absorption per Person (after Rindel), and Density Factor were
calculated and tabulated. The Density Factor (D) is the inverse-density in m2/person (not people
per unit area as usually defines density) and corresponds to a measure of occupant load as used in
common building codes.
Analysis
Scatter plots showing the mean-error-squared (r2
values) for Average Comfort and each of the
physical measures were generated from the
Microsoft Excel spreadsheet:
A degree of correspondence is evident
between Average Comfort and Absorption
per Person, lending some support to
Rindel’s analysis (Fig. 3).
The data does not indicate a strong
correlation between Average Comfort and
Background Noise (r2= 0.140). This is very
surprising considering the number of
studies that assume increased noise in
restaurants results in discomfort (Fig. 4).
There is also no evident correlation
between Average Comfort and many other
room characteristics including Density (r2
= 0.082), Proportions (r2= 0.0122), and
Total Absorption (r2= 0.0396). However,
there is a significant correlation for
Average Comfort and Reverberation Time,
which also indicates an optimal level
between 0.5 and 0.7 seconds (Fig. 5).
R² = 0.3517
2.000
2.200
2.400
2.600
2.800
3.000
3.200
3.400
3.600
3.800
0.50 1.00 1.50 2.00 2.50
Comfort (Average)
Absorption per Person (metric sabins)
Figure 4: Average Comfort and Absorption per Person
R² = 0.14
2.000
2.200
2.400
2.600
2.800
3.000
3.200
3.400
3.600
3.800
65 70 75 80 85
Comfort (Average)
Background Noise (dBC)
Figure 4: Average Comfort and Background Noise
R² = 0.752
2.200
2.400
2.600
2.800
3.000
3.200
3.400
3.600
3.800
0 0.5 1 1.5 2
Comfort (Average)
Reverberation Time
Figure 5: Average Comfort and Reverberation Time
Figure 3: Average Comfort and Absorption per Person
P. Battaglia
Achieving acoustical comfort in restaurants
Proceedings of Meetings on Acoustics, Vol. 22, 015001 (2015)
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Reverberation Time compared to
the averaged responses for the
subjective impressions of
Communication, Quietude and
Privacy yield some interesting
correspondences:
Reverberation Time affects
Privacy (lack of disruption due
to sounds from other tables) to a
large extent (Fig.6).
Quietude (how quiet the space
seems to be) also corresponds
with high significance (Fig. 7).
Communication (ability to
converse with other diners at the
same table) correlates the least
(Fig. 8).
There is a significant agreement
between Average Quietude and
Absorption per Person (r2=
0.4864) and there appears to be
an optimal amount of 1.8 metric
sabins per person (Fig. 9). A
possible explanation: less
absorption would make the
restaurant seem too noisy, and
more absorption would lend too
much clarity to conversations
from diners at adjacent tables.
R² = 0.4801
1.000
1.500
2.000
2.500
3.000
3.500
0 0.5 1 1.5 2
Quietude (Average)
Reverberation Time
R² = 0.6277
2.000
2.200
2.400
2.600
2.800
3.000
3.200
3.400
3.600
0 0.5 1 1.5 2
Privacy (Average)
Reverberation Time
R² = 0.3557
2.000
2.200
2.400
2.600
2.800
3.000
3.200
3.400
3.600
0 0.5 1 1.5 2
Communication (Average)
Reverberation Time
Figure 6: Average Privacy and Reverberation Time
Figure 7: Average Quietude and Reverberation Time
Figure 8: Average Communication and Reverberation
Time
R² = 0.4864
1.000
1.500
2.000
2.500
3.000
3.500
0.50 1.00 1.50 2.00 2.50
Quietude (Average)
Absorption per Person (metric sabins)
Figure 9: Average Quietude and Absorption per Person
P. Battaglia
Achieving acoustical comfort in restaurants
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Comfort by Age Group compared to Reverberation Time shows some expected results with strong
correlations to the data:
Age Group 1 (25 and under) has an optimal 0.7 second reverberation time for Comfort.
Age Groups 2, 3 and 4 (all over 25) all have a constant slope in the plot where higher
reverberation time results in less comfort.
Related to these results is that Comfort in Age Group 1 (25 and under) has no relationship
to Quietude (r2= 0.1468). This may lend some credence to the partying invocation among
the young: “Let’s make some noise.”
Comfort in Age Group 2 (26 to 45) is strongly related to Privacy (sounds from other tables)
compared to other subjective impressions.
The opposite is indicated for Age Group 4 (over 65) where Privacy is not as important to
Comfort as is Quietude and Communication. The general loss of clarity in hearing with
age may account for these results.
Summary
There is no apparent correspondence between background noise and the subjective impression of
acoustical comfort, at least within the 70-84 dBC range of the data set. There is a strong
correspondence between reverberation time and the subjective impression of acoustical comfort.
The data and analysis indicate an optimal range for reverberation time between 0.5 and 0.7 second
will provide acoustical comfort for most restaurant patrons. There also appears to be an optimal
value of 1.8 metric sabins per person (about 20 sabins/person) for attaining the proper level of
background sound.
By inserting these target values into the Sabine equation for reverberation time an equation for
optimal ceiling height can be derived based upon a certain selected density of seating:
For V = H x A (height x area); a = apx C (absorption per person x capacity); D = A/C.
Therefore, when ap= 1.8 metric sabins:
T = .16 V/a = .16 (H x A/1.8 x C) = .16 x H x D/1.8; solving for H,
H = 11.25 T/D (for I-P: H = 400 T/D)
For example, if a restaurateur desires a reverberation time of 0.7 second and a density factor of 1.9
m2/person (20.44 ft2/person) the architect can determine that the optimal height for a desirable
acoustical ambiance is about 4.14 meters (13’-7”): H = 11.25 x 0.7/1.9 = 4.14 meters.
Acoustical comfort is defined differently by age group. The youngest Age Group 1 (under 25)
seems unaffected by a loud background level. Age Group 2 (26-45) associates comfort with
privacy where sounds of conversations from other tables are not disturbing. Age Group 3 (46-65)
wants it all – Quietude, Communication and Privacy. Age Group 4 (over 65) prefers a quiet setting
and an ability to easily converse with other diners at the same table, but sounds from other tables
are not necessarily disturbing.
A good, successful restaurateur begins the design of a new eating establishment by developing the
menu selections followed by the range of prices for the offerings. The menu and price determine
the target clientele, including age range. Since the architect can see from the data analysis
P. Battaglia
Achieving acoustical comfort in restaurants
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presented here, understanding the ages of the patrons expected by the restaurateur is critical to the
design of the proper acoustical conditions for the dining space.
Acknowledgements
I offer my sincere thanks to the restaurateurs who welcomed our students for this study. Especially
I want to thank Dr. Robert Burkard, Chair of the UB Department of Rehabilitation Medicine and
to Cort Lippe, composer and professor in the UB Department of Music , for insights into the
mechanics of hearing and the digital generation of sound.
Finally, congratulations to the wonderful students of the spring 2014 Aural Architecture seminar
from the University at Buffalo whose final (unpublished) papers were used (or not used) in the
compilation of data for this study: Eric Becker (No. 10), Daniel Boyle (No. 7), Bo-Ashley Brindley
(No. 4), Vadim Fedorishin (No. 1), Kristen Gabriele (No. 6), Timothy Gargiulo (No. 13), Shaun
Hyla (No. 2), Xingjian Liao (No. 5), Sungyong Lim (No. 14), Olga Lyubezhanin (No. 15), Richard
Malone (No. 9), Alexey Mokhov (No. 3), Christopher Osterhoudt (No. 16), Steven Parks (No. 17),
Jared Parylo (No. 12), Anthony Santoro (No. 8), and Edward Schelleng (No. 11).
1B. Blesser and L.-R. Salter, Spaces Speak, Are You Listening? Experiencing Aural Architecture, MIT
Press, 2007.
2A. Astolfi and M. Fillippi, “Good acoustical quality in restaurants: A compromise between speech
intelligibility and privacy,” Pro. EuroNoise 2003, Naples, Italy, S102 (2003).
3M. Nahid and M. Hodgson, “Prediction of optimal conditions for verbal-communication quality in eating
establishments,” J. Acoust. Soc. Am. 129(4), 2005-2014 (2011).
4J. Rindel, “Acoustical capacity as a means of noise control in eating establishments,” Joint Baltic-Nordic
Acoustics Meeting 2012, Odense, Denmark (2012).
P. Battaglia
Achieving acoustical comfort in restaurants
Proceedings of Meetings on Acoustics, Vol. 22, 015001 (2015)
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... The often-problematic acoustic environments in restaurants, cafes and dining halls are examined by many researchers who tried to define acceptable and preferred ranges for various performance criteria, such as reverberation time and sound pressure levels. Rindel (2012a), Soyer and Houdet (1986), Astolfi and Filippi (2004), Kang (2006), Hodgson et al. (2009), Battaglia (2014, Svensson et al. (2014), Zelem et al. (2015), Watson and Downey (2008), and Tarlao et al. (2021) investigated acoustics of eating establishments with measurements and questionnaires. In these studies, it is mentioned that a narrow range between 0.5 and 0.7 seconds of reverberation time has been found to provide acoustic comfort for customers (Battaglia 2014) and a reverberation time over 2 seconds can make users uncomfortable (Zelem et al. 2015). ...
... Rindel (2012a), Soyer and Houdet (1986), Astolfi and Filippi (2004), Kang (2006), Hodgson et al. (2009), Battaglia (2014, Svensson et al. (2014), Zelem et al. (2015), Watson and Downey (2008), and Tarlao et al. (2021) investigated acoustics of eating establishments with measurements and questionnaires. In these studies, it is mentioned that a narrow range between 0.5 and 0.7 seconds of reverberation time has been found to provide acoustic comfort for customers (Battaglia 2014) and a reverberation time over 2 seconds can make users uncomfortable (Zelem et al. 2015). Rindel (2012a) proposed the concept of acoustic capacity (N max ), which is defined as the "maximum number of persons allowed in the room for sufficient quality of verbal communication." ...
... Reverberation time has been investigated by many studies in literature. For example, Battaglia (2014) stated that there was a strong relationship between reverberation time and acoustic comfort. Figure 9 shows the relation between reverberation time and acoustic comfort in five eating establishments. ...
Article
Psychoacoustic parameters are mostly used for determining the sound quality of mechanical sounds. They have also started to be used for evaluating soundscapes of open areas and enclosed spaces. This research aims to find out the relationship between the psychoacoustic parameters and acoustic comfort in non-acoustic enclosed public spaces, specifically in eating establishments. Both on-site measurements and laboratory listening tests were conducted for five eating establishments. During on-site measurements, a simultaneous questionnaire study was also carried out. Subjective and objective data were comparatively evaluated. Listening tests were based on auralizations with calibrated simulation models. This provided a research model, that allows control over the acoustic environment without having to make real changes in the physical elements of the eating establishments. The auralization sound files were presented to listening test participants with headphones and they evaluated soundscapes with different psychoacoustic properties. As results, better acoustic comfort was found to be related with higher sharpness, lower reverberation time, lower loudness and lower roughness values for the examined parameter ranges.
... Studies dealing with the influence of the acoustic environment on patrons have predominantly considered music as a relevant factor (e.g., Caldwell and Hibbert, 2002); only a few studies also considered a possible influence of ambient noise (Antun, et al., 2010;Bitner, 1992). One study explicitly focusing on acoustical comfort in restaurants surveyed 11 restaurants and 825 patrons, and obtained acoustical comfort by the four parameters Privacy, Comfort, Quietude and Communication and also measured reverberation time and background noise level as acoustical factors (Battaglia, 2014). The results show that reverberation time predicted each one of the four comfort parameters; also, comfort was predicted by the sound pressure level. ...
... The results show that reverberation time predicted each one of the four comfort parameters; also, comfort was predicted by the sound pressure level. Battaglia (2014) concludes that reverberation times of 0.5-0.7 s are within the optimal range for perceived acoustical comfort. However, his study did not include reverberation times under 0.5 s, so the question remains whether a further lowering of the reverberation time might increase acoustical comfort. ...
... In line with previous findings (e.g., Battaglia, 2014;Gozalo et al., 2015), we further hypothesized that the L A,eq,15 would negatively predict soundscape pleasantness (H2a). Similarly, we expected a negative influence of T 20,occ on soundscape pleasantness (H2b). ...
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Sound and music are well-studied aspects of the quality of experience in restaurants; the role of the room acoustical conditions, their influence on the visitors’ soundscape evaluation and their impact on the overall customer satisfaction in restaurants, however, has received less scientific attention. The present field study therefore investigated whether sound pressure level, reverberation time, and soundscape pleasantness can predict factors associated with overall restaurant quality. In total, 142 persons visiting 12 restaurants in Berlin rated relevant acoustical and non-acoustical factors associated with restaurant quality. Simultaneously, the A-weighted sound pressure level (LA,eq,15) was measured, and the reverberation time in the occupied state (T20,occ) was obtained by measurements performed in the unoccupied room and a subsequent calculation of the occupied condition according to DIN 18041. Results from linear mixed-effects models revealed that both the LA,eq,15 and T20,occ had a significant influence on soundscape pleasantness and eventfulness, whereby the effect of T20,occ was meditated by the LA,eq,15. Also, the LA,eq,15 as well as soundscape pleasantness were significant predictors of overall restaurant quality. A comprehensive structural equation model including both acoustical and non-acoustical factors, however, indicates that the effect of soundscape pleasantness on overall restaurant quality is mediated by the restaurant’s atmosphere. Our results support and extend previous findings which suggest that the acoustical design of restaurants involves a trade-off between comfort and liveliness, depending on the desired character of the place.
... Although the use of sound absorbing materials is well known for the improvement of acoustic comfort in closed rooms/buildings (Battaglia, 2014;Xiao and Aletta, 2016;Thomas et al., 2018), less is known about the use of such materials for the improvement of acoustic comfort for residents of housing complexes with shared inner yards (Taghipour et al., 2019c). Within other exterior spaces of the urban layout, facade absorption has been found to affect the acoustic performance. ...
... In many studies, the improvement of acoustic comfort has been presented as the general improvement of acoustics, measured in objective acoustical and/or room acoustical parameters (such as lower SPL) (Xiao and Aletta, 2016;Thomas et al., 2018). Other studies have used a subjective evaluation of the acoustic comfort (Yang and Kang, 2005;Kang and Zhang, 2010;Battaglia, 2014;Taghipour et al., 2019b), where acoustic comfort was found to be related to the SPL (Yang and Kang, 2005). ...
Article
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Room acoustical parameters have frequently been used to evaluate or predict the acoustical performance in rooms. For housing complexes in urban areas with high population density, it is important to improve acoustic performance not solely indoors, but outdoors as well; for example on the balconies or in the yards. This paper investigates to what extent classic room acoustical parameters would be able to predict the perceived acoustic comfort in outdoor spaces (i.e., courtyards) of virtual housing complexes. Individual and combined effects of a series of independent variables (such as facade absorption, sound source, and observer position) on short-term acoustic comfort were investigated in three laboratory experiments. ODEON software was used for virtual inner yard simulation, whereby 2D spatialization was carried out for a playback over five loudspeakers. Moderate facade absorption was found to increase acoustic comfort. Relatively pleasant and relatively unpleasant sounds were associated with comfort and discomfort, respectively. Lower acoustic comfort ratings were observed at receiver positions with high sound pressure levels and/or strong flutter echoes. A further analysis of the results is carried out here with respect to the room acoustical parameters and their ability to predict the acoustic comfort ratings. Speech transmission index (STI), definition (D50), clarity of speech (C50) and music (C80), early decay time (EDT), and lateral energy fraction (LF80) were found to be significantly correlated with acoustic comfort. They were found to be significant predictors of acoustic comfort in a series of linear mixed-effect models. Furthermore, linear mixed-effect models were established with the A-weighted equivalent continuous sound level, LAeq, as a significant predictor of acoustic comfort.
... The result that LAeq15' is negatively related to soundscape pleasantness is in line with the findings by Gozalo (15), and partly in line with Battaglia who found week correspondence between background noise and the subjective impression of acoustical comfort in restaurants (8). By contrast, it contradicts findings by Zhang et al. (21) who observed positive relationships between LAeq and acoustic comfort in urban open public spaces. ...
... Furthermore, our results suggest, that lower reverberation times lead to higher soundscape pleasantness. This is in line with Battaglia's findings who found that lower reverberation times correlate with acoustical comfort (8). ...
Conference Paper
Studies of the hospitality industry on restaurant quality only partially consider the acoustical side of atmosphere. In contrast, studies on restaurant acoustics make high demands in terms of low reverberation times to account for speech intelligibility. This raises questions regarding the reasons for this discrepancy and desirable auditive characteristics in the context of restaurants. We thus carried out a correlational field study involving a sample of 12 restaurant settings. In this study, we investigated the effect of reverberation time and sound pressure level on customers’ perceived affective quality of the soundscape. In addition, the relationship between soundscape pleasantness and the overall satisfaction with the restaurant was analyzed. Analyses using linear mixed-effects models revealed that the soundscape indicators pleasantness and eventfulness are related to the (room) acoustical parameters sound pressure level and reverberation time. Moreover, soundscape pleasantness judgments were shown to predict overall customer satisfaction. Theoretical and practical implications for the acoustical design of restaurants are discussed.
... These studies investigate the sonic character of open spaces like public gardens, streets, squares, roads and enclosed spaces like libraries, eating establishments, schools, workshops, studios, shopping malls. There are also studies focused on restaurants, cafes and dining halls where the spaces are examined considering acoustics [3][4][5][6][7][8][9][10]. In the study where Soyer and Houdet investigate 18 school dining halls (12 acoustically treated -6 non-treated), it is stated that acoustically treated halls in their research have an LAeq value between 77-82 dBA and the nontreated ones between 81-85 dBA [3]. ...
... Rindel suggests the term 'acoustical capacity' for eating establishments, which is defined as "the maximum number of persons allowed in the room for sufficient quality of verbal communication" [7]. In Battaglia's study, 11 restaurants with reverberation times between 0.4 -1.5 seconds have been evaluated [8]. No relationship has been found between the background noise (70-84 dBC) and acoustic comfort evaluations. ...
Article
Noise in eating establishments has been studied in architectural acoustics literature. For evaluating acoustics in these spaces, researchers predominantly investigate sound pressure levels and reverberation times. Yet, noise in eating spaces originate from a wide variety of sources and is hard to describe and evaluate with only sound pressure levels and reverberation times. Better metrics for acoustics in closed public spaces are needed. Psychoacoustic parameters of loudness, sharpness, fluctuation strength and roughness are promising metrics that have been used by many recent studies evaluating noise annoyance. However, unlike the established metrics such as reverberation time, no set of recommended values exist for these parameters, yet. The aim of this study is to investigate noise in eating establishments through psychoacoustic parameters and understand both the noise characteristics and the metrics themselves. This paper presents a set of sound recordings during lunch hours in two eating spaces in Izmir Institute of Technology. The entry and egress of occupants have been tracked manually, while sound levels have been measured and the noise has been recorded for psychoacoustics analysis. The relationship between the number of occupants and psychoacoustic parameters has been investigated through these objective measurements. The relationship between the number of occupants and sound levels is discussed in the light of the Lombard effect.
... Even the definition of the term "acoustic comfort" is vague and colorful in the literature. While, in many studies, an "improvement in acoustic comfort" meant a general improvement of acoustics and was measured by different sets of objective acoustical or room acoustical parameters (such as lower sound pressure level, SPL) [10,11], other studies used a subjective evaluation of acoustic comfort [9,15,16]. Furthermore, a series of studies measured an improvement in acoustic comfort directly with a decrease in noise annoyance (associated with corresponding decrease in SPL) [17]. While acoustic comfort has been found to be related to the SPL-i.e., L eq (equivalent continuous sound level) or L dn (day-night sound level)- [15], reducing SPL alone might not be a sufficient measure for improving acoustic comfort in urban areas [15,18,19]. ...
... Residents of housing complexes might benefit from the latter, e.g., by controlled absorptions and reflections of the facade. Whereas sound absorbing materials have been frequently used to improve acoustic comfort in closed rooms [9][10][11], little is known about the influences of sound absorbers on the (outside) facade to improve acoustic comfort for residents of housing complexes with shared inner yards. ...
Article
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Housing complex residents in urban areas are not only confronted with typical noise sources, but also everyday life sounds, e.g., in the yards. Therefore, they might benefit from the increasing interest in soundscape design and acoustic comfort improvement. Three laboratory experiments (with repeated-measures complete block designs) are reported here, in which effects of several variables on short-term acoustic comfort were investigated. A virtual reference inner yard in the ODEON software environment was systematically modified by absorbers on building facades, whereby single-channel recordings were spatialized for a 2D playback in laboratory. Facade absorption was found, generally, to increase acoustic comfort. Too much absorption, however, was not found to be helpful. In the absence of any absorbers on the facade, absorbing balcony ceilings tended to improve acoustic comfort, however, non-significantly. Pleasant and unpleasant sounds were associated with comfort and discomfort, accordingly. This should encourage architects and acousticians to create comfortable inner yard sound environments, where pleasant and unpleasant sound occurrence probabilities are designed to be high and low, respectively. Furthermore, significant differences were observed between acoustic comfort at distinct observer positions, which could be exploited when designing inner yards.
... Bu araştırmalarda parklar, caddeler, meydanlar, yollar gibi açık alanlar ve kütüphane, yemekhane, derslik, alışveriş merkezleri, tüneller gibi kapalı alanlar, ses peyzajı asçısından incelenmiştir. Kapalı alanlar arasında özellikle restoran, kafe ve benzeri yemek yenen mekanların akustik açıdan incelendiği çalışmalar da yapılmıştır[3][4][5][6][7][8][9][10]. Soyer ve Houdet'in 12'si akustik olarak düzenlenmiş, diğer 6'sı akustik olarak düzenlenmemiş toplam 18 adet okul yemekhanesinde yaptığı çalışmada, akustiği iyileştirilmiş yemekhanelerin 77-82 dBA arasında, akustik açıdan düzenleme görmemiş yemekhanelerin ise 81-85 dBA aralığında LAeq değerlerine sahip olduğu gözlemlenmiştir[3]. ...
... Battaglia'nın 11 restoranda yapılan çalışmasında ise, fon gürültüsü, çınlama süresi, mekanın boyutları, akustik kapasite, sandalye sayısı ile sessizlik, iletişim, mahremiyet ve konfora dair anket soruları değerlendirilmiştir[8]. Çalışmada incelenen mekanların çınlama süreleri 0,4 ile 1,5 arasında değişmektedir. ...
Conference Paper
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Mekanların akustik açıdan değerlendirmesi yapılırken, sesin şiddeti dışında birçok diğer parametre insan algısını etkilemektedir. Örneğin belirli işlevlere sahip mekanlarda olması beklenen çınlama süreleri literatürde mevcuttur. Bununla birlikte; gürlük, keskinlik, pürüzlülük ve dalgalanım kuvveti gibi psikoakustik parametrelerin, mekan fonksiyonuna bağlı olarak tahmin edilebilir aralıklarda olup olmadığı kesinliğe kavuşmuş bir konu değildir. Bu bildiride, İYTE merkezi yemekhanesinde yapılan ölçümler üzerinden, yemek yeme eylemi esnasında çıkan konuşma, çatal – bıçak, sandalye ve benzeri seslerin oluşturduğu ses peyzajı, psikoakustik parametreler açısından değerlendirilmiştir. Aynı zaman aralığında ve farklı günlerde yapılan ölçümler ile yapılan kayıtlarda, sabit bir aralıkta kalan değerler olup olmadığı gözlemlenmiştir. Daha sonra yemekhane ölçümleri, kütüphanede yapılan ölçüm serisi ile kıyaslanarak psikoakustik parametreler incelenmiştir. [Evaluation of a dining hall soundscape in terms of psychoacoustic parameters] Besides sound pressure level, many other parameters affect human perception while evaluating spaces in terms of acoustics. As an example, recommended reverberation times are defined for certain space functions. However, generally accepted value ranges for psychoacoustic parameters like loudness, sharpness, fluctuation strength and roughness do not exist. This paper presents a set of recordings during lunch hours in the main dining hall and working hours in the library at Izmir Institute of Technology. Both soundscapes are investigated in terms of psychoacoustic parameters.
Article
Sound level data and occupancy data have been logged in five restaurants by the research team at the University of Nebraska – Lincoln. Sound levels and occupancy at 10 second intervals were documented over time periods of roughly two hours during active business hours. Noise levels were logged with dosimeters distributed throughout each restaurant, and occupancy was obtained from images recorded by infrared cameras. This work presents data on average sound levels and statistical metrics, such as L10 and L90 values as well as on each restaurant’s Acoustical Capacity and Quality of Verbal Communication, as introduced by Rindel (2012). Acoustical Capacity is a metric describing the maximum number of persons for reasonable communication in a space, calculated from the unoccupied reverberation time and the volume of the space. Quality of Verbal Communication is a metric describing the ease with which persons in the space can communicate at a singular point in time, depending on the reverberation time, the volume of the space, and the number of occupants in the space. This work also aims to confirm the validity of Rindel’s predictive model (2010). Advisor: Lily M. Wang
Conference Paper
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Many restaurants have smooth rigid surfaces made of wood, steel, glass, and concrete. This often results in a lack of sound absorption. Such restaurants are notorious for high sound noise levels during service that most owners actually desire for representing vibrant eating environments, although surveys report that noise complaints are on par with poor service. This study investigated the relation between objective acoustic parameters and subjective evaluation of acoustic comfort at five restaurants in terms of three parameters: noise annoyance, speech intelligibility, and privacy. At each location, customers filled out questionnaire surveys, acoustic parameters were measured, and recordings of restaurant acoustic scenes were obtained with a 64-channel spherical array. The acoustic scenes were reproduced in a virtual sound environment (VSE) with 64 loudspeakers placed in an anechoic room, where listeners performed subjective evaluation of noise annoyance and privacy and a speech intelligibility test for each restaurant noise background. It was found that subjective evaluations of acoustic comfort correlate with occupancy rates and measured noise levels, that survey and listening test results agreed well and that, in the VSE, speech reception thresholds were similar for the five reproduced restaurant backgrounds.
Conference Paper
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Questo studio focalizza la sua attenzione sulle mense aziendali valutando, tramite una serie di indagini oggettive e soggettive, il disagio acustico sia dei lavoratori che dei fruitori. Gli alti livelli di rumore e un'acustica della sala non corretta, in generale sono in grado di causare effetti negativi sulla persona, sia dal punto di vista fisico sia psicologi-co. Questi effetti sono, inoltre, accentuati sui soggetti portatori di deficit uditivi e che utilizzano protesi acustiche. Gli Autori hanno messo a punto un protocollo che comprende sia la raccolta di dati soggettivi, tramite questionari, sia oggettivi attraverso la misura dei livelli di rumore, di diversi parametri acustici architettonici per poi correlarli. Saranno qui presentati i risul-tati di un'indagine pilota effettuata su una mensa. I questionari sono stati somministrati ad un campione costituito da 6 addetti alla ristorazione e 140 fruitori di età compresa tra 25 e 65 anni.
Article
This paper discusses the prediction of verbal-communication quality in eating establishments (EEs). EEs contain talkers and listeners who require high speech intelligibility at their tables, and high speech privacy between tables. Using catt-Acoustic, verbal-communication quality--quantified by speech transmission index (STI)--in models of three existing EEs was predicted. Talker voice-output levels were predicted using an existing empirical model accounting for the Lombard effect. With these, catt-Acoustic predicted impulse responses, speech levels and noise levels at primary and secondary listener positions, and the corresponding STIs. The untreated EEs were first modeled for various talker and listener positions, and occupancies. Then various treated configurations, involving reduced volume, increased absorption and barriers were studied to determine the effectiveness of the treatments. The results suggest that placing barriers around tables can be an effective way to achieve good verbal-communication quality. Increasing the absorption of the room surfaces or decreasing the ceiling height to control reverberation may not be effective. However, increasing the surface absorption and putting barriers around tables may achieve optimal speech conditions in EEs. Subdividing large EEs into smaller ones can also be effective.