scholarly journals Unsupervised analysis of background noise sources in active offices

2021 ◽  
Vol 149 (6) ◽  
pp. 4049-4060
Author(s):  
Domenico De Salvio ◽  
Dario D'Orazio ◽  
Massimo Garai
Keyword(s):  
Background Noise ◽  
Noise Sources ◽  
Unsupervised Analysis

scholarly journals Modeling and Mapping of Combined Noise Annoyance for Aircraft and Road Traffic Based on a Partial Loudness Model

2021 ◽  
Vol 18 (16) ◽  
pp. 8724
Author(s):  
Wonhee Lee ◽  
Chanil Chun ◽  
Dongwook Kim ◽  
Soogab Lee
Keyword(s):  
Background Noise ◽  
Road Traffic ◽  
Noise Source ◽  
Transportation Systems ◽  
Masking Effect ◽  
Noise Sources ◽  
Noise Annoyance ◽  
Short And Long Term ◽  
Loudness Model

Complex transportation systems often produce combined exposure to aircraft and road noise. Depending on the noise source, the annoyance response is different, and a masking effect occurs between the noise sources within the combined noise. Considering these characteristics, partial loudness was adopted to evaluate noise annoyance. First, a partial loudness model incorporating binaural inhibition was proposed and validated. Second, short- and long-term annoyance models were developed using partial loudness. Finally, the annoyance of combined noise was visualized as a map. These models can evaluate the annoyance by considering both the intensity and frequency characteristics of the noise. In addition, it is possible to quantify the masking effect that occurs between noise sources. Combined noise annoyance maps depict the degree of annoyance of residents and show the background noise effect, which is not seen on general noise maps.

Background Noise Effects on Combustor Stability

2002 ◽  
Author(s):  
Tim Lieuwen ◽  
Andrzej Banaszuk
Keyword(s):  
Acoustic Waves ◽  
Background Noise ◽  
Noise Sources ◽  
Turbulent Fluctuations ◽  
Number Systems ◽  
Damping Rate ◽  
Parametric Noise ◽  
High Reynolds ◽  
The Stability ◽  
Stability Limits

This paper considers the effects of background turbulent fluctuations upon a combustor’s stability boundaries. Inherent turbulent fluctuations act as both additive and parametric (also called multiplicative) excitation sources to acoustic waves in combustors. While additive noise sources exert primarily quantitative effects upon combustor oscillations, parametric noise sources can exert qualitative impacts upon its dynamics; particularly of interest here is their ability to destabilize a “nominally” stable system. The significance of these parametric noise sources increases with increased background noise levels and, thus, may play more of a role in realistic, high Reynolds number systems than experiments on simplified, lab scale combustors might suggest. The objective of this paper is to determine whether and/or when these effects might be significant. The analysis considers the effects of fluctuations in damping rate, frequency and combustion response. It is found that the effects of noisy damping and frequency upon the combustor’s stability limits is quite small, at least for the fluctuation intensities estimated here. The effects of a noisy combustion response, particularly of a fluctuating time delay between flow and heat release perturbations, can be quite significant, however, in some cases for turbulence intensities as low as <(u′/u¯)2>1/2∼5–10%. These results suggest that deterministic stability models calibrated on low turbulence intensity, lab scale combustors may not adequately describe the stability limits of realistic, highly turbulent combustors.

scholarly journals Improvements of a Hard-Wall Closed Test-Section of a Subsonic Wind Tunnel for Aeroacoustic Testing

2021 ◽  
Vol 26 (3) ◽  
pp. 248-258
Author(s):  
Odenir de Almeida ◽  
Fernando M. Catalano ◽  
Lourenco Tercio Pereira
Keyword(s):  
Wind Tunnel ◽  
Test Section ◽  
Background Noise ◽  
Noise Sources ◽  
Subsonic Wind Tunnel ◽  
Array Measurements ◽  
Before And After ◽  
Noise Measurements ◽  
Low Speed Wind Tunnel ◽  
Lower Background

For achieving accurate aeroacoustic measurements to the aircraft industry, a low-speed wind tunnel, primarily designed for aerodynamic testing, is modified to provide lower background noise environment. Based on data from single microphone at different wind tunnel locations and microphone phased-array measurements inside the test-section, the main noise sources are identified and feasible alternatives are implemented for reducing the background noise such as new acoustically treated corner-vanes and sidewall lining located upstream the drive system. The acoustically transparent concept for the test-section is also investigated showing promising results for further improvements in the wind tunnel. Results are presented for sound pressure levels from single microphone measurements at different locations in the wind tunnel as well as from the beamforming array inside the test-section. Background noise measurements before and after improvements confirm that the ability of performing aeroacoustic tests has significantly increased with noise reduction of 5 dB inside the test-section.

Cavitation Detection Using Wavelet Denoising

Volume 3 ◽  
2004 ◽  
Author(s):  
Joseph P. Welz ◽  
Matthew P. Iannacci ◽  
David M. Jenkins
Keyword(s):  
Real Time ◽  
Measurement Technique ◽  
Background Noise ◽  
Static Pressure ◽  
Wavelet Denoising ◽  
Stationary Object ◽  
Noise Sources ◽  
Accepted Practice ◽  
Cavitation Detection ◽  
Damage Prevention

Cavitation in turbomachinery provides a source of damage to the hydrodynamic surfaces. Detection of cavitation at the earliest possible time after inception is desirable from a damage prevention standpoint. In order to detect cavitation in real time, acoustic sensing of the cavitation events has long been an accepted practice. A problem with this measurement technique is the potential contamination from electrical and acoustic background noise sources. This work employs an algorithm based on wavelet denoising. The wavelet denoising algorithm depends on a measurement of the acoustic background noise in the absence of cavitation. Cavitation measurements of a stationary object are evaluated with and without the application of the denoising process. The results of this comparison indicate that the wavelet denoising procedure allows an increased number of cavitation events to be detected at a given static pressure, and cavitation is detected at higher pressures than previous techniques.

Contribution of non‐verbal and non‐ventilation noise sources to background noise levels in elementary school classrooms.

2011 ◽  
Vol 129 (4) ◽  
pp. 2523-2523
Author(s):  
Alex Hornecker ◽  
Clothilde Giacomoni ◽  
Michelle C. Vigeant ◽  
Robert D. Celmer
Keyword(s):  
Elementary School ◽  
Background Noise ◽  
Noise Levels ◽  
Noise Sources

scholarly journals Aircraft and Background Noise Annoyance Effects

1983 ◽  
Vol 27 (1) ◽  
pp. 52-52
Author(s):  
Kelli F. Willshire
Keyword(s):  
Noise Level ◽  
Background Noise ◽  
Signal To Noise Ratio ◽  
Body Movement ◽  
Movement Analysis ◽  
Aircraft Noise ◽  
Air Conditioner ◽  
Noise Sources ◽  
Community Noise ◽  
Noise Annoyance

Traditionally, community aircraft flyover annoyance has been studied in the absence of other noises. However, the importance of considering the flyovers along with other community noise sources is gaining increasing awareness. To investigate annoyance of multiple noise sources, two experiments were conducted. The first experiment used 48 subjects, and the second used 216 subjects. The first experiment was designed to establish annoyance-noise level functions for three community noise sources presented individually: jet aircraft flyovers, air conditioner, and traffic. This experiment provided baseline data for a second experiment which is currently being conducted to investigate (1) effects of background noise on aircraft annoyance as a function of noise level and spectrum shape; (2) the relative contributions of background noises and aircraft noise to overall annoyance; and (3) effect of type of annoyance rating: overall or source specific. In the second experiment, the subjects were required to make either overall or source specific annoyance ratings or a combination of the two. Both experiments used two dependent measures: rated annoyance and amount of subconscious body movement or fidgeting. Results of the first experiment indicated that the slope of the annoyance-noise level function for traffic was significantly different from the slopes corresponding to flyover and air conditioner noise. This added further justification to the need to determine the influence of different background noises on aircraft noise annoyance (e.g., experiment two). Preliminary body movement analysis indicated no relationship of body movements to source noise level. Results of the second experiment showing differential effects of signal-to-noise ratio and background source type across total noise level will be presented and discussed. Results will also be presented to illustrate the effects of all the sources (flyover, air conditiner, and traffic) on relative annoyance as a function of the type of annoyance questionnaire. Further data on the correlation of movement with source noise level will be discussed. However, based on the results of the first experiment, little relation to annoyance is expected. All results will be applied in an effort to develop an improved model of human response to community noise.

scholarly journals Noise Risk Assessment at Air Separation Plant PT. X Surabaya (Nitrogen, Oxygen, and Argon Plant)

2017 ◽  
Vol 1 (2) ◽  
pp. 70
Author(s):  
Hanif Rizqi Diniari ◽  
Tofan Agung Eka Prasetya ◽  
Erwin Dyah Nawawiwetu ◽  
Abdul Rohim Tualeka
Keyword(s):  
Background Noise ◽  
Noise Intensity ◽  
Intensity Measurement ◽  
Air Separation ◽  
Risk Level ◽  
Noise Sources ◽  
Separation Plant ◽  
Cross Sectional ◽  
Measurement Result ◽  
Descriptive Research

Background : Noise was one of the dangerous factors at a workplace which causes various effects on workers. Purpose :  The purpose of this research was to described the activity stages, identified the noise danger, and assessed the risk and its level at Air Separation Plant of PT. X. Methods : This research was a descriptive research with a cross sectional approach. The object of the research was the noise danger potential and the noise risk level assessment at Air Separation Plant of PT. X. Results : The result of this research showed that there were 12 identified noise danger points. These results consisted of 5 (42 %) noise risks with low category, 2 (16 %) with middle category, and another 5 (42 %) with high category. The highest noise intensity measurement result was found on Recycle Nitrogen Compressor (RNC) machine, which was 116,5 dBA.  Conclusion :  Based on this data, it can be concluded that there were 12 identified noise danger points and the highest noise intensity measurement result was found on Recycle Nitrogen Compressor (RNC) machine, which was 116,5 dBA. It is suggested for the related company to execute controls mostly in diminishing the noise sources.

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