An impedance tube for precision measurement of acoustic impedance and insertion loss at high sound pressure levels

1973 ◽  
Vol 28 (1) ◽  
pp. 23-IN1 ◽  
Author(s):  
T.H. Melling
Keyword(s):  
Insertion Loss ◽  
Precision Measurement ◽  
Acoustic Impedance ◽  
Sound Pressure ◽  
Impedance Tube ◽  
Sound Pressure Levels ◽  
High Sound

scholarly journals Automotive traffic noise and urban public spaces

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.

scholarly journals Improving the noise reduction by green roofs due to solar panels and substrate shaping

2018 ◽  
Vol 25 (3) ◽  
pp. 219-232 ◽  
Author(s):  
Timothy Van Renterghem
Keyword(s):  
Noise Reduction ◽  
Insertion Loss ◽  
Sound Pressure ◽  
Road Traffic ◽  
Green Roof ◽  
Green Roofs ◽  
Road Traffic Noise ◽  
Back Side ◽  
Solar Panels ◽  
Sound Pressure Levels

The urban fabric largely consists of acoustically rigid materials. This not only affects sound pressure levels in streets, but also how sound propagates towards the back side of a building or to connected urban canyons. A green roof is a practical solution to have roof absorption, mitigating diffracting sound waves. Flat green roofs were shown to provide roughly 3 dBA urban road traffic noise reduction relative to a common flat rigid roof. Although already relevant, it has been numerically studied in this work how the green roof insertion loss of flat roofs can be further increased. Solar panels on green roofs were found to significantly decrease sound pressure levels at the shielded building facade, up to 5 dBA on top of the insertion loss of granular substrates. Polyurethane foam slabs as green roof substrates provide relevant shielding when placed on a series of hollow trapezium-like cores of sufficient height.

Acoustic Resistance of an Orifice at High Sound Pressure Levels

2018 ◽  
Vol 64 (5) ◽  
pp. 563-566 ◽  
Author(s):  
A. I. Komkin ◽  
A. I. Bykov ◽  
M. A. Mironov
Keyword(s):  
Sound Pressure ◽  
Sound Pressure Levels ◽  
Acoustic Resistance ◽  
High Sound

scholarly journals Environmental ultrasound in laboratories and animal houses: a possible cause for concern in the welfare and use of laboratory animals

1988 ◽  
Vol 22 (4) ◽  
pp. 369-375 ◽  
Author(s):  
G. D. Sales ◽  
K. J. Wilson ◽  
K. E. V. Spencer ◽  
S. R. Milligan
Keyword(s):  
Sound Pressure ◽  
Visual Display ◽  
Laboratory Animals ◽  
Upper Limit ◽  
Sound Pressure Levels ◽  
Hearing Range ◽  
Human Hearing ◽  
High Sound ◽  
Possible Cause

Many laboratory animals are known to be sensitive to sounds (ultrasounds) beyond the nominal upper limit (20 kHz) of the human hearing range. Sources of sound in laboratories and animal houses were examined to determine the extent of ambient ultrasound. Of 39 sources monitored, 24 were found to emit ultrasonic sounds. Many of these (e.g. cage washers and hoses) also produced sound in the audible range. Running taps, squeaky chairs and rotating glass stoppers created particularly high sound pressure levels and contained frequencies to over 100 kHz. The oscilloscopes and visual display units investigated provided particular cause for concern as they emitted sounds that were entirely ultrasonic and therefore were apparently silent. Ambient ultrasound therefore appears to be common in laboratories and animal houses. It is suggested that its effect on laboratory animals should be investigated and guidelines on acceptable levels be formulated.

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