Noise generation by vacuum cleaner suction units. Part III. Contribution of structure-borne noise to total sound pressure level

2007 ◽  
Vol 68 (5) ◽  
pp. 521-537 ◽  
Author(s):  
Mirko Čudina ◽  
Jurij Prezelj
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Pressure Level ◽  
Noise Generation ◽  
Vacuum Cleaner

A Study of Noise Generation on the E387, S823, NACA 0012, and NACA 4412 Airfoils for Use on Small-Scale Wind Turbines in the Urban Environment

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Kenneth W. Van Treuren ◽  
Andrew W. Hays
Keyword(s):  
Wind Tunnel ◽  
Wind Turbines ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Reynolds Numbers ◽  
Pressure Level ◽  
Small Scale ◽  
Noise Prediction ◽  
Noise Generation ◽  
Naca 0012

Four airfoils typical to small-scale wind turbines were studied for noise generation: Eppler 387, NREL S823, NACA 0012, and NACA 4412. Wind tunnel sound pressure level (SPL) data were collected directly downstream of the airfoil for angles of attack from −10 deg to 25 deg and for Reynolds numbers from 50,000 to 200,000. Vertical and horizontal wake traverses define the extent of the noise generated. The data were analyzed by frequency and compared with a noise prediction from NREL AirFoil Noise (NAFNoise). The noise trends found can be applied to improve other airfoil selection when designing small-scale wind turbines.

scholarly journals RESEARCH INTO NOISE GENERATED BY DOMESTIC APPLIANCES IN THE ANECHOIC CHAMBER / BUITINIŲ PRIETAISŲ SKLEIDŽIAMO TRIUKŠMO TYRIMAI TRIUKŠMO SLOPINIMO KAMEROJE

2012 ◽  
Vol 5 (4) ◽  
pp. 441-447
Author(s):  
Agnė Žukauskienė ◽  
Raimondas Grubliauskas
Keyword(s):  
Environmental Protection ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Negative Impact ◽  
Pressure Level ◽  
Anechoic Chamber ◽  
Entire Body ◽  
Loud Noise ◽  
Vacuum Cleaner ◽  
Domestic Appliances

Loud noise has a negative impact on the entire body, especially on listening. We can hear daily noise everywhere – in the street, at work or at home. The Department of Environmental Protection of Vilnius Gediminas Technical University has adjusted an anechoic chamber adapted for suppressing sound. Under the above introduced conditions, 15 appliances (5 vacuum cleaners, 5 hair dryers and 5 shaving machines) have been tested. Equivalent sound pressure level of the vacuum cleaner has varied from 66 dBA to 83 dBA, that of the hair dryer has made from 64 dBA to 70 dBA and for the shaving machine – from 39 to 56 dBA. Santrauka Straipsnyje aptariamas triukšmo keliamas neigiamas poveikis žmogaus organizmui. Paaiškinamos triukšmo bei buitinio prietaiso sąvokos. Pateikiama informacija nuo kokio lygio triukšmas laikomas pavojingu žmogaus sveikatai. Vilniaus Gedimino technikos universiteto aplinkos apsaugos katedroje, specialiai tam pritaikytoje triukšmo slopinimo kameroje atliktas tyrimas su 15 buitinių prietaisų (5 dulkių siurbliais, 5 plaukų džiovintuvais, bei 5 barzdaskutėmis). Nustatytas šių buitinių prietaisų ekvivalentinis, maksimalus bei minimalus keliamo triukšmo lygis. Visų prietaisų triukšmo lygis pateikiamas 1/1 oktavos dažnių juostose (63 Hz –16 kHz). Lyginami gauti buitinių prietaisų triukšmo tyrimo rezultatai. Dulkių siurblių ekvivalentinis triukšmo lygis siekia nuo 66 dBA iki 83 dBA, plaukų džiovintuvų – nuo 64 dBA iki 70 dBA, barzdaskučių – nuo 39 dBA iki 56 dBA.

Contributions of Voice and Nonverbal Communication to Perceived Masculinity–Femininity for Cisgender and Transgender Communicators

2020 ◽  
Vol 63 (4) ◽  
pp. 931-947
Author(s):  
Teresa L. D. Hardy ◽  
Carol A. Boliek ◽  
Daniel Aalto ◽  
Justin Lewicke ◽  
Kristopher Wells ◽  
...  
Keyword(s):  
Fundamental Frequency ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Vocal Tract ◽  
Presentation Mode ◽  
Pressure Level ◽  
Presentation Modes ◽  
Audiovisual Stimuli ◽  
Vocal Tract Resonance ◽  
Point Light

Purpose The purpose of this study was twofold: (a) to identify a set of communication-based predictors (including both acoustic and gestural variables) of masculinity–femininity ratings and (b) to explore differences in ratings between audio and audiovisual presentation modes for transgender and cisgender communicators. Method The voices and gestures of a group of cisgender men and women ( n = 10 of each) and transgender women ( n = 20) communicators were recorded while they recounted the story of a cartoon using acoustic and motion capture recording systems. A total of 17 acoustic and gestural variables were measured from these recordings. A group of observers ( n = 20) rated each communicator's masculinity–femininity based on 30- to 45-s samples of the cartoon description presented in three modes: audio, visual, and audio visual. Visual and audiovisual stimuli contained point light displays standardized for size. Ratings were made using a direct magnitude estimation scale without modulus. Communication-based predictors of masculinity–femininity ratings were identified using multiple regression, and analysis of variance was used to determine the effect of presentation mode on perceptual ratings. Results Fundamental frequency, average vowel formant, and sound pressure level were identified as significant predictors of masculinity–femininity ratings for these communicators. Communicators were rated significantly more feminine in the audio than the audiovisual mode and unreliably in the visual-only mode. Conclusions Both study purposes were met. Results support continued emphasis on fundamental frequency and vocal tract resonance in voice and communication modification training with transgender individuals and provide evidence for the potential benefit of modifying sound pressure level, especially when a masculine presentation is desired.

Case study: Theoretical calculation model and variable condition analysis research on the water-splashing noise for natural draft wet cooling towers

2020 ◽  
Vol 68 (2) ◽  
pp. 137-145
Author(s):  
Yang Zhouo ◽  
Ming Gao ◽  
Suoying He ◽  
Yuetao Shi ◽  
Fengzhong Sun
Keyword(s):  
Theoretical Model ◽  
Sound Pressure Level ◽  
Water Droplet ◽  
Water Distribution ◽  
Sound Pressure ◽  
Cooling Tower ◽  
Distribution Patterns ◽  
Calculation Model ◽  
Pressure Level ◽  
Cooling Towers

Based on the basic theory of water droplets impact noise, the generation mechanism and calculation model of the water-splashing noise for natural draft wet cooling towers were established in this study, and then by means of the custom software, the water-splashing noise was studied under different water droplet diameters and water-spraying densities as well as partition water distribution patterns conditions. Comparedwith the water-splashing noise of the field test, the average difference of the theoretical and the measured value is 0.82 dB, which validates the accuracy of the established theoretical model. The results based on theoretical model showed that, when the water droplet diameters are smaller in cooling tower, the attenuation of total sound pressure level of the water-splashing noise is greater. From 0 m to 8 m away from the cooling tower, the sound pressure level of the watersplashing noise of 3 mm and 6 mm water droplets decreases by 8.20 dB and 4.36 dB, respectively. Additionally, when the water-spraying density becomes twice of the designed value, the sound pressure level of water-splashing noise all increases by 3.01 dB for the cooling towers of 300 MW, 600 MW and 1000 MW units. Finally, under the partition water distribution patterns, the change of the sound pressure level is small. For the R s/2 and Rs/3 partition radius (Rs is the radius of water-spraying area), when the water-spraying density ratio between the outer and inner zone increases from 1 to 3, the sound pressure level of water-splashing noise increases by 0.7 dB and 0.3 dB, respectively.

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