Design of silencer using resonator arrays with high sound pressure and grazing flow

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.

Download Full-text

Automotive traffic noise and urban public spaces

Revista Nacional de Gerenciamento de Cidades ◽

10.17271/2318847297220212964 ◽

2021 ◽

Vol 9 (72) ◽

Author(s):

Greicikelly Gaburro Paneto ◽

Cristina Engel de Alvarez ◽

Paulo Henrique Trombetta Zannin

Keyword(s):

Urban Space ◽

Sound Pressure ◽

Traffic Noise ◽

Motor Vehicles ◽

Open Spaces ◽

Sound Levels ◽

Measurement Results ◽

Sound Pressure Levels ◽

High Sound

In contemporary cities, and usually without realizing it, the population has been exposed to high sound pressure levels, which besides causing discomfort, can lead to health problems. Considering that a large part of this noise comes from emission from motor vehicles, this research aims to evaluate the sound behavior in sound environments configured by voids in the urban fabric, in order to identify whether open spaces can act as attenuators of sound levels. To obtain the expected results, the methodology used was structured from a review of the state-of-the-art and computer simulations relating the variables that influence the formation of urban space and sound emission and propagation, taking as a case study an urban portion of the municipality of Vitória/ES. In parallel, questionnaires were applied to evaluate the user's perception of their exposure. The measurement results indicated that the sound pressure levels caused by traffic noise are above the limit tolerated limit by the NBR norm 10151:2000 for the daytime period. In turn, the results obtained from the population indicated that there is little perception of noise by the users of the spaces surveyed.

Download Full-text

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

10.1115/imece2001/htd-24390 ◽

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.

Download Full-text

Acoustic Simulation’s Verification of WFI ATHENA Filterwheel Assembly

Archives of Acoustics ◽

10.1515/aoa-2017-0051 ◽

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.

Download Full-text

Noise Power Spectrum for Firecrackers

International Journal of Artificial Life Research ◽

10.4018/jalr.2011010107 ◽

2011 ◽

Vol 2 (1) ◽

pp. 62-70 ◽

Cited By ~ 1

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.

Download Full-text