scholarly journals Determination of thermal and acoustic comfort inside a vehicle’s cabin

2018 ◽  
Vol 32 ◽  
pp. 01002
Author(s):  
Alexandra Ene ◽  
Tiberiu Catalina ◽  
Andreea Vartires
Keyword(s):  
Thermal Comfort ◽  
Air Temperature ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Pressure Level ◽  
The Other ◽  
Air Velocity ◽  
Acoustic Comfort ◽  
Comfort Parameters

Thermal and acoustic comfort, inside a vehicle’s cabin, are highly interconnected and can greatly influence the health of the passengers. On one hand, the H.V.A.C. system brings the interior air parameters to a comfortable value while on the other hand, it is the main source of noise. It is an intriguing task to find a balance between the two. In this paper, several types of air diffusers were used in order to optimize the ratio between thermal and acoustic interior comfort. Using complex measurements of noise and thermal comfort parameters we have determined for each type of air diffuser the sound pressure level and its impact on air temperature and air velocity.

Two Methods to Test Transducer Array Directivity

2014 ◽  
Vol 912-914 ◽  
pp. 1485-1488
Author(s):  
Hong Liu ◽  
Guo Zhu Zhao
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Beam Width ◽  
Directivity Pattern ◽  
Acute Angle ◽  
Pressure Level ◽  
The Other ◽  
Transducer Array ◽  
Acoustic Transducer ◽  
The One

An array which possess more array element number and whose frequency of the drive signal can be as large as possible in a range, directivity will be more preferable. On the other hand, when the structure of the sound radiating surface of the transducer or array layout is symmetrical, the corresponding directivity pattern will be symmetrical. In order to test transducer directivity, two methods are designed. The one is to measure the ultrasonic sound pressure level by instruments. The sound pressure level is measured at multiple points to deduce the directivity angle of the acoustic transducer array. The beam width of the 3×3 array is about at 23kHz, and the directivity acute angle is about 10°; higher frequencies will lead to the side lobes, but it can be negligible when compared to the main lobe. The other method is using the frequency analyzer to test transducer directivity in a silencer chamber. The sound pressure level can be read out from frequency response diagrams. The angle between the sound pressure value that decreasing 3db from the max value 111.7db and the max value is about 11°. So the directivity acute angle is about 11°. It should be noticed that, as the directivity diagram can not be directly attributed, there is some deviation in the conclusion.

DETERMINATION OF MONOPOLE AND DIPOLE SOURCES OF FLOW AROUND A CYLINDER USING A VIRTUAL MICROPHONE ARRAY

Akustika ◽  
2021 ◽  
pp. 76
Author(s):  
Victor Ershov ◽  
Igor Khramtsov ◽  
Oleg Kustov
Keyword(s):  
Numerical Simulation ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Microphone Array ◽  
Pressure Level ◽  
Noise Sources ◽  
Ansys Fluent ◽  
Flow Around A Cylinder ◽  
Vortex Shedding Frequency

In this paper, the problem of localization of noise sources of flow around a cylinder was considered on the basis of a computational experiment using a virtual 54-channel microphone array. Numerical simulation was performed using the computational fluid dynamics software ANSYS Fluent. Several spatial orientations of the cylinder were considered for the generation of dipoles with different directions. Simulation of a simplified two-microphone azimuthal decomposition technique (ADT) is performed to determine the sound pressure level of the generated dipoles at a vortex shedding frequency of 1450 Hz. A procedure of localization of the noise of the flow around a virtual cylinder was performed using monopole and dipole beamforming algorithms. It was found that the numerical simulation results are in good agreement with the data obtained by other researchers, both in terms of the sound pressure level and the results of the localization of dipoles in space.

Unsteady Isentropic Flow through Ducts with Prescribed Sound Pressure Level Distribution

1995 ◽  
Vol 117 (3A) ◽  
pp. 279-284 ◽  
Author(s):  
J. G. Cherng ◽  
Tsung-Yen Na
Keyword(s):  
Sound Pressure Level ◽  
Unknown Parameter ◽  
Sound Pressure ◽  
Flow Speed ◽  
Pressure Level ◽  
Cross Sectional ◽  
Isentropic Flow ◽  
First Case ◽  
Flow Through

An analytical method for the determination of the required shape of a duct for a prescribed sound pressure level distribution is presented in this paper. The physical model involves a sound wave propagating in an unsteady flow of compressible fluids through ducts. Two cases are considered. In the first case, the channel shape, F(X), is given as either an exponential function or a linear function of the distance along the axis with an unknown parameter in the expression for F(X). The unknown parameter is determined by the prescribed ratio of the sound pressure level at the exit section of the duct to that at the entrance. In the second case, the sound pressure level is specified at every point along the length of the duct, and the duct shape, F(X), is sought. The governing differential equations of the model are presented. The method of complex superposition is used to separate the real and the imaginary parts of the perturbation quantities. The results show that the cross-sectional area is sensitive to the flow speed and the frequency of the sound source. Furthermore, a convergent/divergent duct has to be used to achieve a linear sound pressure level distribution.

A Criterion for Predicting the Annoyance Due to Lower Level Low Frequency Noise

1983 ◽  
Vol 2 (4) ◽  
pp. 160-168 ◽  
Author(s):  
N. Broner ◽  
H.G. Leventhall
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Low Frequency ◽  
Threshold Effect ◽  
Pressure Level ◽  
The Other ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Estimation Task ◽  
Noise Annoyance

In a study of the annoyance due to low frequency noise, 75 subjects (consisting of 21 complainants and 54 controls) carried out a magnitude estimation task and rated the annoyance due to lower-level low frequency noise (55dB–75dB). After allowing for a threshold effect, it was found that the E-weighted sound pressure level was, in general, the best predictor of lower-level low frequency noise annoyance. However, it was not a significantly better predictor than any of the other nine noise measures considered. The widely available dB(A) noise measure was therefore suggested as a useful predictor of group annoyance due to lower-level low frequency noise.

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