scholarly journals Acoustic Simulation’s Verification of WFI ATHENA Filterwheel Assembly

2017 ◽  
Vol 42 (3) ◽  
pp. 483-489
Author(s):  
Adam Pilch ◽  
Tadeusz Kamisinski ◽  
Mirosław Rataj ◽  
Szymon Polak
Keyword(s):  
Main Part ◽  
Sound Pressure ◽  
Pressure Level ◽  
Noise Levels ◽  
Large Area ◽  
Fem Simulations ◽  
Absorbing Material ◽  
Reduce Risk ◽  
High Sound ◽  
Very High

Abstract Ariane 5 rocket produces very high sound pressure levels during launch, what can influence structures located in the fairing. To reduce risk of damage, launch in vacuum conditions is preferred for noise sensitive instruments. In Wide Filed Imager (WFI) project, the main part of the filterwheel assembly is an extremely thin (~240 nm) filter of large area (170×170 mm), very sensitive to noise and vibrations. The aim of this study was to verify numerical calculations results in anechoic measurements. The authors also checked the influence of WFI geometry and sound absorbing material position on sound pressure level (SPL) affecting the filter mounted inside the assembly. Finite element method (FEM) simulations were conducted in order to obtain noise levels in filter position during Ariane 5 rocket launch. The results will be used in designing of WFI filterwheel assembly and endurance of the filter during launch verification.

Influence of the Acoustic Reflex on Vowel Recognition

1986 ◽  
Vol 29 (3) ◽  
pp. 420-424 ◽  
Author(s):  
Michael Dorman ◽  
Ingrid Cedar ◽  
Maureen Hannley ◽  
Marjorie Leek ◽  
Julie Mapes Lindholm
Keyword(s):  
Auditory System ◽  
Sound Pressure ◽  
Dynamic Range ◽  
Recognition Accuracy ◽  
Pressure Level ◽  
Acoustic Reflex ◽  
The Poor ◽  
Stapedial Reflex ◽  
Vowel Recognition ◽  
High Sound

Computer synthesized vowels of 50- and 300-ms duration were presented to normal-hearing listeners at a moderate and high sound pressure level (SPL). Presentation at the high SPL resulted in poor recognition accuracy for vowels of a duration (50 ms) shorter than the latency of the acoustic stapedial reflex. Presentation level had no effect on recognition accuracy for vowels of sufficient duration (300 ms) to elicit the reflex. The poor recognition accuracy for the brief, high intensity vowels was significantly improved when the reflex was preactivated. These results demonstrate the importance of the acoustic reflex in extending the dynamic range of the auditory system for speech recognition.

scholarly journals Status of noise pollution in urban area of Dharan Sub- Metropolitan City and Inaruwa Municipality of Sunsari District, Nepal

2017 ◽  
Vol 7 (1) ◽  
pp. 35-40
Author(s):  
Ranij Shrestha ◽  
Alankar Kafle ◽  
Kul Prasad Limbu
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Pollution Assessment ◽  
Noise Pollution ◽  
Pressure Level ◽  
Noise Levels ◽  
Night Time ◽  
Level Measurement ◽  
Standard Value ◽  
Autumn And Winter

The environmental noise level measurement in Dharan and Inaruwa cities of eastern Nepal were conducted and compared with the ambient noise standards provided by Government of Nepal. The noise pollution assessment was performed in autumn and winter seasons by the indicator average day time sound pressure level (Ld, during 7.00 to 22.00 hrs) and average night time sound pressure level (Ln, during 22.00 to 7.00 hrs). The Ld and Ln values at the commercial, silence and residential zones of Dharan were 78 to 82 and 72 to 73, 65 to 73 and 60 to 70, 65 to 76 and 62 to 64 dB(A) in autumn and 78 to 79 and 72 to 76, 64 to 71 and 58 to 68, 63 to 74 and 60 to 62 dB(A) in winter, respectively whereas for Inaruwa, measurement were 75 to 77 and 73 to 75, 59 and 57, 67 and 60 dB(A) in autumn and 66 to 70 and 63 to 68, 55 and 53, 65 and 58 dB(A) in winter, respectively. The results showed that noise levels exceeded the standard value at most of the sites.

Design of Generator Acoustic Blanket and its Impact on Generator Cooling Performance

2001 ◽  
Author(s):  
Wei Tong
Keyword(s):  
Sound Pressure ◽  
Noise Exposure ◽  
Cost Effective ◽  
Design Stage ◽  
Cooling Load ◽  
Noise Levels ◽  
Cooling Performance ◽  
Early Design Stage ◽  
Blanket Design ◽  
High Sound

Abstract Generator noise is one of the primary concerns in generator designs. The most cost-effective way to deal with the noise issue is to incorporate the reduction of sound pressure level in an early design stage. Once a generator is manufactured, it is often expensive to modify the design for reducing noise levels. For old generators with high sound pressure levels, an effective method to lower the generator noise exposure is to employ acoustic blankets wrapped on the generator external surfaces. However, with the application of acoustic blankets, heat transfer through generator walls can be greatly reduced, leading to the higher generator core temperature and higher generator cooling load. This paper has addressed the design of generator acoustic blankets and its impact on generator cooling performance. The analysis has shown that the influence of acoustic blankets on the generator thermal performance is low or moderate. This suggests that the current acoustic blanket design is feasible. Results from this study have been used to optimize the blanket design.

scholarly journals Reducing the harmful effects of noise on the human environment. Sound insulation of industrial skeleton enclosures in the 10–40 kHz frequency range

2020 ◽  
Vol 18 (2) ◽  
pp. 1451-1463
Author(s):  
Witold Mikulski
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Sheet Steel ◽  
Pressure Level ◽  
Sound Insulation ◽  
Frequency Range ◽  
Noise Sources ◽  
Human Environment ◽  
Absorbing Material ◽  
Acoustic Enclosures

Abstract Purpose The purpose of the research is to work out a method for determining the sound insulation of acoustic enclosures for industrial sources emitting noise in the frequency range of 10–40 kHz and apply the method to measure the sound insulation of acoustic enclosures build of different materials. Methods The method is developed by appropriate adaptation of techniques applicable currently for sound frequencies of up to 10 kHz. The sound insulation of example enclosures is determined with the use of this newly developed method. Results The research results indicate that enclosures (made of polycarbonate, plexiglass, sheet aluminium, sheet steel, plywood, and composite materials) enable reducing the sound pressure level in the environment for the frequency of 10 kHz by 19–25 dB with the reduction increasing to 40–48 dB for the frequency of 40 Hz. The sound insulation of acoustic enclosures with a sound-absorbing material inside reaches about 38 dB for the frequency of 10 kHz and about 63 dB for the frequency of 40 kHz. Conclusion Some pieces of equipment installed in the work environment are sources of noise emitted in the 10–40 kHz frequency range with the intensity which can be high enough to be harmful to humans. The most effective technical reduction of the associated risks are acoustic enclosures for such noise sources. The sound pressure level reduction obtained after provision of an enclosure depends on its design (shape, size, material, and thickness of walls) and the noise source frequency spectrum. Realistically available noise reduction values may exceed 60 dB.

Noise Power Spectrum for Firecrackers

2011 ◽  
Vol 2 (1) ◽  
pp. 62-70 ◽  
Author(s):  
K. B. Patange ◽  
A. R. Khan ◽  
S. H. Behere ◽  
Y. H. Shaikh
Keyword(s):  
Sound Pressure ◽  
Impulsive Noise ◽  
Power Spectra ◽  
Noise Power ◽  
Human Beings ◽  
Noise Levels ◽  
Different Types ◽  
Noise Measurements ◽  
Pressure Peak ◽  
High Sound

Frequency of noise can affect human beings in different ways. The sound of firecrackers is a type of intensive impulsive noise, which is hazardous. In this paper, the noise produced by firecrackers during celebration festivals in Aurangabad (M.S.), India is measured. The noise is analyzed from the study of power spectra for different types of firecrackers. Noise measurements of firecrackers show that they produce high sound pressure peak levels at their characteristics frequencies. Plots of noise power versus frequency for different crackers are presented and the inferences are discussed. Typical firecracker peak noise levels are given.

scholarly journals So Small, So Loud: Extremely High Sound Pressure Level from a Pygmy Aquatic Insect (Corixidae, Micronectinae)

PLoS ONE ◽  
2011 ◽  
Vol 6 (6) ◽  
pp. e21089 ◽  
Author(s):  
Jérôme Sueur ◽  
David Mackie ◽  
James F. C. Windmill
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Aquatic Insect ◽  
Pressure Level ◽  
High Sound

Electroacoustic Characteristics of Personal FM Systems

1982 ◽  
Vol 47 (4) ◽  
pp. 355-362 ◽  
Author(s):  
David B. Hawkins ◽  
Dianne J. Van Tasell
Keyword(s):  
Hearing Aids ◽  
Sound Pressure ◽  
Internal Noise ◽  
Pressure Level ◽  
Volume Control ◽  
Clinical Use ◽  
Noise Levels ◽  
Response Curves ◽  
Direct Input ◽  
System Configurations

Electroacoustic characteristics of various personal FM system configurations were obtained through the use of a Zwislocki ear simulator and KEMAR. Saturation Sound Pressure Level 90 and frequency response curves were obtained with different hearing aids in the microphone mode and then compared to the response obtained when the hearing aids were coupled to a FM receiver via neck loops and direct input. In addition, hearing aid orientation to and distance from the loop, clothing effects, internal noise levels, FM receiver volume control taper, and the effect of different FM receivers were investigated. The results indicated substantial microphone-teleloop response differences. Only minor differences were observed in the microphone-direct input comparison. Other variables were found that significantly affect the use of these personal FM systems. The results are discussed in terms of the implications for clinical use.

scholarly journals THICKNESS INFLUENCE ON ABSORBING PROPERTIES OF STRATIFIED COMPOSITE MATERIALS

2015 ◽  
Vol 21 (4) ◽  
pp. 28-34
Author(s):  
IULIANA IAȘNICU (STAMATE) ◽  
OVIDIU VASILE ◽  
RADU IATAN
Keyword(s):  
Composite Material ◽  
Sound Pressure ◽  
Layered Composite ◽  
Sound Level ◽  
Pressure Level ◽  
Sound Level Meter ◽  
Absorbing Materials ◽  
Absorbing Material ◽  
Study Case ◽  
Level Meter

Plates known as sound absorbing materials: textiles recovered fabrics plus polyethylene are made layered composite material intended to be used to encapsulate industrial engines, as sources of noise in the production departments. Influence of thickness sound-absorbing material can be supported by the values obtained for the absorption coefficient, but it can be studied as a study case in the anechoic chamber, where the sound pressure level is measured with a sound level meter. Cases captured: a free engine; the engine placed in a metallic cube and motor inserted; metal cube that was doubled separately with one material and then with the composite material proposed. For each situation are eight determinations on the perimeter of a circle with a radius of one meter from the source of the noise. Plot a graph of experimental results that support the idea: greater thickness of the layer of material will cause a better absorption of noise.

Firecrackers Noise

2003 ◽  
Vol 34 (5) ◽  
pp. 9-12 ◽  
Author(s):  
N. Tandon
Keyword(s):  
Impulse Noise ◽  
Sound Pressure ◽  
Measurement Methods ◽  
Noise Levels ◽  
The World ◽  
Noise Measurements ◽  
Pressure Peak ◽  
Hearing Damage ◽  
High Sound

Fireworks are used all over the world to celebrate special occasions. Noise produced by firecrackers that are used to celebrate these occasions has been highlighted. This impulse type of noise can cause hearing damage. Noise measurements of firecrackers show that they produce high sound pressure peak levels. Typical firecracker impulse noise levels are given. Noise limits and measurement methods used for the fireworks in some countries are presented.

scholarly journals Prediction of Turbulent Boundary Layer Induced Noise in the Cabin of a BWB Aircraft

2012 ◽  
Vol 19 (4) ◽  
pp. 693-705 ◽  
Author(s):  
Joana Rocha ◽  
Afzal Suleman ◽  
Fernando Lau
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Sound Pressure ◽  
Pressure Level ◽  
Interior Noise ◽  
Analytical Models ◽  
Frequency Range ◽  
Noise Levels ◽  
Cabin Noise ◽  
Cabin Interior

This paper discusses the development of analytical models for the prediction of aircraft cabin noise induced by the external turbulent boundary layer (TBL). While, in previous works, the contribution of an individual panel to the cabin interior noise was considered, here, the simultaneous contribution of multiple flow-excited panels is analyzed. Analytical predictions are presented for the interior sound pressure level (SPL) at different locations inside the cabin of a Blended Wing Body (BWB) aircraft, for the frequency range 0–1000 Hz. The results show that the number of vibrating panels significantly affects the interior noise levels. It is shown that the average SPL, over the cabin volume, increases with the number of vibrating panels. Additionally, the model is able to predict local SPL values, at specific locations in the cabin, which are also affected with by number of vibrating panels, and are different from the average values.

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