The effect of sound masking on employees' acoustic comfort and performance in open-plan offices in Canada

2021 ◽  
Vol 263 (1) ◽  
pp. 5678-5683
Author(s):  
Roderick Mackenzie ◽  
Joonhee Lee ◽  
Vincent Le Men ◽  
Farideh Zarei
Keyword(s):  
Work Performance ◽  
Signal To Noise Ratio ◽  
Sound Level ◽  
Sound Levels ◽  
Before And After ◽  
Acoustic Comfort ◽  
Sound Environment ◽  
Open Plan ◽  
Sound Masking ◽  
And Performance

Sound masking systems are commonly used in open-plan offices to generate a controlled minimum level of background sound, in order to decrease the signal-to-noise ratio of intrusive speech and blend out transient office noise. However, a question in the acoustical design of offices is whether the self-generated noise of occupants may alone be sufficient to provide the background sound level conditions necessary to achieve similar levels of speech privacy and acoustic comfort as sound masking systems. This study examines the relationship between occupant-perceived speech privacy and acoustic comfort under three different acoustic scenarios (no masking, controlled 42 dBA, and 47 dBA masking sound levels). The study was conducted pre-COVID-19 in two separate open-plan offices located in Quebec, Canada that at the time were close to full occupancy. Employees completed subjective questionnaires before and after each change in conditions, focusing on how the sound environment impacted their comfort and work performance during the study. Statistical results show that the occupants were significantly more satisfied during the two sound masking conditions in comparison to the no-masking condition, where only the occupant-generated and exterior/mechanical system noise was present as the background sound. Implications for open-plan offices with lower occupancy conditions post-COVID-19 are discussed.

scholarly journals Influence of the Acoustic Cover of the Modular Expansion Joint on the Acoustic Climate in the Bridge Structure Surroundings

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2842
Author(s):  
Janusz Bohatkiewicz ◽  
Michał Jukowski ◽  
Maciej Hałucha ◽  
Marcin Dębiński
Keyword(s):  
Sound Level ◽  
Structural Elements ◽  
Expansion Joint ◽  
Expansion Joints ◽  
The Road ◽  
Sound Levels ◽  
Road Surfaces ◽  
Before And After ◽  
Bridge Structures

The noise generated at the interface between the wheels of vehicles and the road surface is well recognized in the literature worldwide. Many publications describe the phenomenon of reducing this kind of impact by silent road surfaces. A specific type of this noise is the sound generated by vehicles passing over the expansion joints of bridge structures. Due to the impulsive nature of this sound, it is very onerous for people living in the close vicinity of bridge structures. The passage of vehicles over expansion joints causes the formation of vibrations that are transmitted to the structural elements of bridge structures, which may cause the formation of the material sounds (especially arduous in the case of bridges with steel elements). An attempt to reduce this impact was made by making a prototype acoustic cover of the expansion joint on the selected bridge. The paper presents the results of research on the “in situ” acoustic effectiveness of this cover. Additionally, the noise was modelled in the object surroundings before and after the cover’s application. The acoustic efficiency of the cover in the whole measured frequency range was 5.3 dBA. In the narrower frequency bands (1/3 octave bands), larger sound level reductions were observed. The maximum sound levels measured under the tested dilatation were less than 10.0 dBA lower than the maximum sound levels measured under the reference dilatation.

scholarly journals Sound Quality Characteristics of Importance for Preschool Children’s Perception and Wellbeing After an Acoustic Intervention

2021 ◽  
Vol 7 ◽  
Author(s):  
Kerstin Persson Waye ◽  
Jonas Karlberg
Keyword(s):  
Oral Communication ◽  
Sound Level ◽  
Preschool Age ◽  
Acoustic Environment ◽  
Children's Perceptions ◽  
Children’S Perceptions ◽  
Sound Levels ◽  
Preschool Age Children ◽  
Sound Environment ◽  
Bodily Sensations

In Sweden preschool-age children spend most of their waking hours at preschool. At this age children undergo substantial physical and mental development and their hearing sensations may not be comparable to those of an adult. The preschool sound environment is loud and highly intermittent, and the acoustic may not be supportive for young children’s hearing, and wellbeing. This article describes an acoustic intervention among seven preschools, and comparisons with three reference preschools. The intervention included changing floor mats to plastic mats designed to reduce impact sounds, adding damping cushions under chairs, change of ceiling absorbers and, in some rooms, addition of wall absorbers. The effect of the intervention was studied using a previously developed interview protocol, “Inventory of Noise and Children’s Health,” in combination with sound level and room acoustic measurements. A total of 61 children aged 4–6 years were interviewed before the intervention, and 56 after. A reduction of the sound levels in a range of LAeq 1.2–3.8 dB for meal/craft rooms and play rooms were found for the intervention preschools using stationary noise level meters, while this was not found for the reference preschools. The reverberation time (T20) decreased slightly after the interventions. The average room frequency response for the two room types tended to be more flat after the interventions. Further investigations are needed to see its importance for the perceived acoustic quality. The results linking children’s perception and response to the measured reduction in sound levels, confirmed an association between reduced sound levels after the acoustic intervention and a 30% reduction in stomach ache, as well as in children’s perceptions of scraping, screeching sounds. Children’s perceptions of these sounds were further associated with important oral communication outcomes. Children’s bodily sensations of sounds were also associated with psychoacoustic symptoms and wellbeing. Despite the seemingly modest reduction in sound level, the acoustic intervention was indeed perceived and reported on by the children. Future studies should pay more attention to how a supportive preschool acoustic environment should be optimised and acoustically described to take preschool-age hearing and perception into account.

Tutorial and Guidelines on Measurement of Sound Pressure Level in Voice and Speech

2018 ◽  
Vol 61 (3) ◽  
pp. 441-461 ◽  
Author(s):  
Jan G. Švec ◽  
Svante Granqvist
Keyword(s):  
Sound Pressure Level ◽  
Background Noise ◽  
Sound Pressure ◽  
Signal To Noise Ratio ◽  
Practical Experience ◽  
Sound Level ◽  
Pressure Level ◽  
Sound Levels ◽  
Frequency Weighting ◽  
Voice And Speech

Purpose Sound pressure level (SPL) measurement of voice and speech is often considered a trivial matter, but the measured levels are often reported incorrectly or incompletely, making them difficult to compare among various studies. This article aims at explaining the fundamental principles behind these measurements and providing guidelines to improve their accuracy and reproducibility. Method Basic information is put together from standards, technical, voice and speech literature, and practical experience of the authors and is explained for nontechnical readers. Results Variation of SPL with distance, sound level meters and their accuracy, frequency and time weightings, and background noise topics are reviewed. Several calibration procedures for SPL measurements are described for stand-mounted and head-mounted microphones. Conclusions SPL of voice and speech should be reported together with the mouth-to-microphone distance so that the levels can be related to vocal power. Sound level measurement settings (i.e., frequency weighting and time weighting/averaging) should always be specified. Classified sound level meters should be used to assure measurement accuracy. Head-mounted microphones placed at the proximity of the mouth improve signal-to-noise ratio and can be taken advantage of for voice SPL measurements when calibrated. Background noise levels should be reported besides the sound levels of voice and speech.

The effects of masking sound and signal-to-noise ratio on work performance in Chinese open-plan offices

2021 ◽  
Vol 172 ◽  
pp. 107657
Author(s):  
Yuanyuan Zhang ◽  
Dayi Ou ◽  
Shengxian Kang
Keyword(s):  
Work Performance ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
Open Plan ◽  
Noise Ratio

Sound Levels in Classrooms and Effects on Self-Reported Mood among School Children

2003 ◽  
Vol 96 (3_suppl) ◽  
pp. 1289-1299 ◽  
Author(s):  
Pär Lundquist ◽  
Kjell Holmberg ◽  
Lage Burström ◽  
Ulf Landström
Keyword(s):  
School Children ◽  
Sound Level ◽  
Work Environments ◽  
Task Orientation ◽  
Sound Exposure ◽  
Recorded Sound ◽  
Sound Levels ◽  
Sound Environment ◽  
Exposure Levels ◽  
Lower Background

The principle of this field study is an investigation of recorded sound levels in 24 classrooms and relations between sound level measures and aspects of children's rated annoyance, task orientation, and inattentiveness. The background sound-exposure levels were distributed within the interval of 33–42 dB(A)eq and the activity sound level exposure ranged between 47–68 dB(A)eq. The recorded levels must be considered as high for work environments where steady concentration and undisturbed communication is essential. Results do not support the hypothesis that lower background-sound level and fewer students per class would improve the sound environment by generating a lower activity noise or the hypothesis that higher sound levels should increase annoyance and inattentiveness as well as deteriorate task orientation ratings.

scholarly journals Underwater Sound Levels in Glacier Bay During Reduced Vessel Traffic Due to the COVID-19 Pandemic

2021 ◽  
Vol 8 ◽  
Author(s):  
Christine M. Gabriele ◽  
Dimitri W. Ponirakis ◽  
Holger Klinck
Keyword(s):  
Harbor Seal ◽  
Sound Level ◽  
Underwater Sound ◽  
Ecological Processes ◽  
Acoustic Environment ◽  
Glacier Bay ◽  
Cruise Ships ◽  
Sound Levels ◽  
Sound Environment ◽  
Vessel Noise

The global COVID-19 pandemic caused a sharp decline in vessel traffic in many areas around the world, including vessel-based tourism throughout Alaska, USA in 2020. Marine vessel traffic has long been known to affect the underwater acoustic environment with direct and indirect effects on marine ecological processes. Glacier Bay National Park in southeastern Alaska has monitored underwater sound since 2000. We used continuous, calibrated hydrophone recordings to examine 2020 ambient sound levels compared with previous years: 2018, the most recent year with data available, and 2016 for historical perspective. Park tourism occurs mainly in May–September. Overall, the number of vessel entries in Glacier Bay was 44–49% lower in 2020 (2020: n = 1,831; 2018: n = 3,599; 2016: n = 3,212) affecting all vessel classes, including the complete absence of cruise ships and only three tour vessel trips. In all years, we found clear seasonal and diurnal patterns in vessel generated noise, focused from 06:00 to 20:00 local time (LT) in the summer months. Broadband (17.8–8,910 Hz) sound levels in the 2020 Visitor Season were 2.7 dB lower than 2018 and 2.5 dB lower than 2016. Focusing on morning (06:00–09:00 LT) and afternoon (15:00–18:00 LT) time-blocks when tour vessels and cruise ships enter and exit Glacier Bay, median broadband sound levels were 3.3–5.1 dB lower in 2020 than prior years. At the 95th percentile levels, morning and afternoon peak times in 2020 were 6.3–9.0 dB quieter than previous years. A 3 dB decline in median sound level in the 125 Hz one-third octave band in 2020 reflects a change in medium and large vessel noise energy and/or harbor seal vocalizations. Our results suggest that all types of vessels had a role in the quieter underwater sound environment in 2020, with the combined acoustic footprint of tour vessels and cruise ships most evident in the decrease in the 95th percentile loudest sounds. This and other descriptions of the pandemic-induced quiet, and the gradual return to increased activity, can help inform efforts to improve existing methods to mitigate vessel noise impacts and maintain the ecological integrity of marine protected areas.

Spatial uniformity tolerances for sound masking systems in open-plan offices

2021 ◽  
Vol 263 (1) ◽  
pp. 5643-5649
Author(s):  
Roderick Mackenzie ◽  
Farideh Zarei ◽  
Vincent Le Men
Keyword(s):  
Sound Field ◽  
Sound Level ◽  
Fine Grid ◽  
Office Space ◽  
Ambient Sound ◽  
Spatial Uniformity ◽  
Field Uniformity ◽  
Open Plan ◽  
Discrete Measurement ◽  
Sound Masking

Electronic sound masking systems raise the ambient sound level in offices to a controlled minimum sound level in order to increase speech privacy and reduce distractions. Sound masking systems are calibrated to provide the most uniform sound field achievable, as a spatially non-uniform masking sound field could result in occupant perception and uneven speech privacy conditions. Tolerances for acceptable spatial uniformity vary between specifiers, and may be based on different evaluation methods using only a few discrete measurement points to represent an entire office space. However, the actual uniformity of a masking sound field across an office, and the parameters influencing it, has not been widely investigated. Thus, this study aims to investigate the masking sound uniformity in a typical open-plan office space using fine-grid measurements conforming to measurement method of ASTM E1573-18. Percentages of measured locations where the sound pressure levels were within specified tolerances (with increments of 0.5 dB) were calculated using the measured 1/3 octave band levels. The research also utilized geometric acoustical simulations to investigate how physical office parameters (number of loudspeakers, partition heights, ceiling absorption, and diffusion characteristics) affect the sound field uniformity of the sound masking system.

Effect of visual elements on Indoor soundscape perception in open-plan office

2021 ◽  
Vol 263 (1) ◽  
pp. 5161-5165
Author(s):  
Beta Bayu Santika ◽  
Hyun In Joo ◽  
Jin Yong Jeon
Keyword(s):  
Work Performance ◽  
Subjective Evaluation ◽  
Visual Stimuli ◽  
Work Productivity ◽  
Computer Software ◽  
Design Guideline ◽  
Visual Elements ◽  
3D Engine ◽  
Sound Environment ◽  
Open Plan

This study examined the effect of changes in visual elements on spatial comfort and work productivity in the aspect of indoor soundscape perception in the open-plan office (OPO) sound environment. Various OPO visual stimuli were simulated using computer software (Unity 3D engine) to change the visual environment by varying variables such as worker density, window ratio, green ratio, and ceiling height. An interactive virtual reality environment was implemented to perform a specific task while experiencing the audio-visual stimuli combining the general OPO noise stimulus and the simulated OPO visual stimulus. Subjective evaluation was performed on a total of 30 subjects to evaluate indoor soundscape quality and work performance for each stimulus. Based on the results of this study, a pleasant OPO design guideline was proposed. Keywords: Open-plan office, indoor soundscape, interactive VR test, spatial comfort

Optimization of Noise and Vibration of a Cylindrical Cam Mechanism Using Inertial Compensation Techniques

1997 ◽  
Author(s):  
Song Lin Ge ◽  
Giovanni Nerli ◽  
Monica Carfagni
Keyword(s):  
Considerable Effect ◽  
Sound Level ◽  
Noise And Vibration ◽  
Remarkable Effect ◽  
Cam Mechanism ◽  
Compensation Systems ◽  
Sound Levels ◽  
Before And After ◽  
The Difference ◽  
The Impact

Abstract An innovative concept has been developed in which the dynamic behaviour of a cylindrical cam mechanism is modified using inertial compensation techniques. Elastic and magnetic compensation systems are incorporated in the experimental acoustic and acceleration analysis procedure. Both compensation systems have a remarkable effect on the reduction of the noise and vibration levels produced by the impact between the cam follower and the groove inversions. However, individually they both have different influences on the groove junctions. Generally they both have a considerable effect on the integral cam mechanism in terms of reducing emitted sound levels. The results also show that the difference in emitted sound levels before and after modification is approximately 3 dB. This conclusion means that the difference of the equivalent sound level is roughly equal to a reduction of about thirty percent below the original level with the compensation devices in position.

scholarly journals Model-based imputation of sound level data at thoroughfare using computational intelligence

2021 ◽  
Vol 11 (1) ◽  
pp. 519-527
Author(s):  
Michał Kekez
Keyword(s):  
Random Forest ◽  
Computational Intelligence ◽  
Sound Level ◽  
Training Data ◽  
Training Dataset ◽  
Scaling Functions ◽  
Sound Levels ◽  
Level Data ◽  
Impute Data ◽  
Before And After

Abstract The aim of the paper was to present the methodology of imputation of the missing sound level data, for a period of several months, in many noise monitoring stations located at thoroughfares by applying one model which describes variability of sound level within the tested period. To build the model, at first the proper set of input attributes was elaborated, and training dataset was prepared using recorded equivalent sound levels at one of thoroughfares. Sound level values in the training data were calculated separately for the following 24-hour sub-intervals: day (6–18), evening (18–22) and night (22–6). Next, a computational intelligence approach, called Random Forest was applied to build the model with the aid of Weka software. Later, the scaling functions were elaborated, and the obtained Random Forest model was used to impute data at two other locations in the same city, using these scaling functions. The statistical analysis of the sound levels at the abovementioned locations during the whole year, before and after imputation, was carried out.

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