MEMS microphone intensity array for cabin noise measurements

2021 ◽  
Vol 263 (3) ◽  
pp. 3023-3034
Author(s):  
Carsten Spehr ◽  
Daniel Ernst ◽  
Hans-Georg Raumer
Keyword(s):  
Sound Intensity ◽  
Phase Match ◽  
Acoustic Energy ◽  
Low Frequencies ◽  
Cabin Noise ◽  
Noise Simulation ◽  
Mems Microphone ◽  
Noise Measurements ◽  
Mems Microphones ◽  
Absorbing Material

Aircraft cabin noise measurements in flight are used toto quantify the noise level, and to identify the entry point of acoustic energy into the cabin. Sound intensity probes are the state-of-the-art measurement technique for this task. During measurements, additional sound absorbing material is used to ease the rather harsh acoustic measurement environment inside the cabin. In order to decrease the expensive in-flight measurement time, an intensity array approach was chosen. This intensity probe consists of 512 MEMS-Microphones. Depending on the frequency, these microphones can be combined as an array of hundreds of 3D- intensity probes. The acoustic velocity is estimated using a high order 3D finite difference stencil. At low frequencies, a larger spacing is used to reduce the requirement of accurate phase match of the microphone sensors. Measurements were conducted in the ground-based Dornier 728 cabin noise simulation as well as in-flight.

Structural Source Identification from Acoustic Measurements Using an Energetic Approach

2017 ◽  
Vol 34 (4) ◽  
pp. 431-441 ◽  
Author(s):  
A. Samet ◽  
M. A. Ben Souf ◽  
O. Bareille ◽  
M. N. Ichchou ◽  
T. Fakhfakh ◽  
...  
Keyword(s):  
Energy Method ◽  
Numerical Test ◽  
Acoustic Energy ◽  
Vibration Source ◽  
Radiated Noise ◽  
Acoustic Cavity ◽  
Energetic Approach ◽  
Structural Force ◽  
Noise Measurements ◽  
Acoustic Energy Density

AbstractAn inverse energy method for the identification of the structural force in high frequency ranges from radiated noise measurements is presented in this paper. The radiation of acoustic energy of the structure coupled to an acoustic cavity is treated using an energetic method called the simplified energy method. The main novelty of this paper consists in using the same energy method to solve inverse structural problem. It consists of localization and quantification of the vibration source through the knowledge of acoustic energy density. Numerical test cases with different measurement points are used for validation purpose. The numerical results show that the proposed method has an excellent performance in detecting the structural force with a few acoustical measurements.

Enhancement of acoustic absorption of a rigidly backed poroelastic plate with periodic elliptic inclusions

2019 ◽  
Vol 33 (30) ◽  
pp. 1950367
Author(s):  
Hongbo Zhang ◽  
Bilong Liu
Keyword(s):  
Material Properties ◽  
Composite Plate ◽  
Incidence Angle ◽  
Major Axis ◽  
Acoustic Energy ◽  
Absorption Peak ◽  
Acoustic Absorption ◽  
The Finite Element Method ◽  
Solid Materials ◽  
Low Frequencies

Perfect acoustic absorption is an important issue for a lot of applications. In this paper, a rigidly backed poroelastic plate with periodic elliptic inclusions is proposed to achieve perfect acoustic absorption at low frequencies by using the finite element method (FEM) with the porous material considered as fluid and solid materials. The absorption of the acoustic energy in such a composite plate resulting from viscous and thermal losses is enhanced by the resonances of the inclusions and energy trapping between the upper part of the poroelastic plate and the inclusion at low frequencies. The influence of the geometry, the incidence angle and the material properties on the absorption coefficient are investigated in detail. Our results show that increasing the major axis of the inclusion, the first absorption peak is pushed to lower frequencies and its value is first increased upto one and then it is decreased. The major axis is the most important parameter to tune the absorption peak, when the thickness is not changed. Once the major axis is determined, perfect acoustic absorption persists even if other parameters are changed. The reported results pave the way for the design of absorption devices which could be used to solve the major issue of noise control.

scholarly journals Using a Planar Array of MEMS Microphones to Obtain Acoustic Images of a Fan Matrix

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Lara del Val ◽  
Alberto Izquierdo ◽  
Juan José Villacorta ◽  
Luis Suárez
Keyword(s):  
Microelectromechanical Systems ◽  
Processing System ◽  
Signal Acquisition ◽  
Acoustic Images ◽  
Mems Microphone ◽  
The Matrix ◽  
Planar Array ◽  
Mems Microphones ◽  
The Individual ◽  
Signal Acquisition And Processing

This paper proposes the use of a signal acquisition and processing system based on an8×8planar array of MEMS (Microelectromechanical Systems) microphones to obtain acoustic images of a fan matrix. A3×3matrix of PC fans has been implemented to perform the study. Some tests to obtain the acoustic images of the individual fans and of the whole matrix have been defined and have been carried out inside an anechoic chamber. The nonstationary signals received by each MEMS microphone and their corresponding spectra have been analyzed, as well as the corresponding acoustic images. The analysis of the acoustic signals spectra reveals the resonance frequency of the individual fans. The obtained results reveal the feasibility of the proposed system to obtained acoustic images of a fan matrix and of its individual fans, in this last case, in order to estimate the real position of the fan inside the matrix.

Airframe noise measurements on JAXA Jet Flying Test Bed “Hisho” using a phased microphone array

2017 ◽  
Vol 16 (4-5) ◽  
pp. 255-273 ◽  
Author(s):  
Takehisa Takaishi ◽  
Hiroki Ura ◽  
Kenichiro Nagai ◽  
Yuzuru Yokokawa ◽  
Mitsuhiro Murayama ◽  
...  
Keyword(s):  
Microphone Array ◽  
Low Frequency ◽  
Landing Gear ◽  
Frequency Resolution ◽  
Test Bed ◽  
Noise Sources ◽  
Low Frequencies ◽  
Airframe Noise ◽  
Noise Measurements ◽  
Wooden Platform

In 2015, the Japan Aerospace Exploration Agency launched the Flight demonstration of QUiet technology to Reduce nOise from High-lift configurations project to verify by flight demonstration the feasibility of practical noise-reducing aircraft modification concepts. In order to serve as a baseline for comparison before modification, airframe noise sources of the JAXA Jet Flying Test Bed “Hisho” were measured with a 30 m diameter array of 195 microphones mounted on a wooden platform built temporary beside the runway of Noto Satoyama Airport in Japan. A classical Delay and Sum in the time domain beamforming algorithm was adapted for the present study, with weight factors introduced to improve the low-frequency resolution and autocorrelations eliminated to suppress wind noise at high frequencies. In the landing configuration at idle thrust, the main landing gear, nose landing gear, and side edges of the six extended flap panels were found to be the dominant “Hisho” airframe noise sources. Deconvolution by the DAMAS and CLEAN-SC algorithms provided clearer positions of these sound sources at low frequencies. Integration of acoustical maps agreed well with the sound pressure level measured by a microphone placed at the center of the microphone array and gave detailed information about the contribution of each noise source.

Multi-Modal Acoustic Flow Decomposition Examined in a Hard Walled Cylindrical Duct

2015 ◽  
Vol 39 (2) ◽  
pp. 289-296 ◽  
Author(s):  
Stefan Weyna ◽  
Witold Mickiewicz
Keyword(s):  
Acoustic Waves ◽  
Sound Propagation ◽  
Practical Interest ◽  
Sound Intensity ◽  
Wide Band ◽  
Acoustic Energy ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
Circular Duct ◽  
Duct Geometry

Abstract Flow fields could be of great interest in the study of sound propagation in aeroengines. For ducts with rigid boundaries, the fluid-resonant category may contribute significantly to unwanted noise. An understanding of the multi-modal propagation of acoustic waves in ducts is of practical interest for use in the control of noise in, for example, aero-engines, automotive exhaust and heating or ventilation systems. The purpose of our experiments was to test the acoustic energy transmission of duct modes based on studies carried out by the sound intensity technique. Sound intensity patterns in circular duct are discussed of modal energy analysis with particular reference to proper orthogonal decomposition and dynamic mode decomposition. The authors try to justify some advantages of the sound intensity experimental research in this area. In the paper, the wide-band sound signal propagated from source approximated with loudspeaker in hard-walled duct is imaged using a sound intensity - based approach. For a simple duct geometry, the sound intensity field is examined visually and by performing a modal decomposition greater insight into the acoustic structures is obtained. The image of sound intensity fields below and above “cut-off” frequency region are found to compare acoustic modes which might resonate in duct.

scholarly journals Is the Frequency Content of the Calls in North American Treefrogs Limited by Their Larynges?

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Marcos Gridi-Papp
Keyword(s):  
Frequency Modulation ◽  
Sound Intensity ◽  
Frequency Content ◽  
Frequency Range ◽  
Low Frequencies ◽  
High Frequencies ◽  
Mating Calls ◽  
Limited Frequency ◽  
Positive Direct ◽  
High Diversity

A high diversity of mating calls is found among frogs. The calls of most species, however, are simple, in comparison to those of mammals and birds. In order to determine if the mechanics of the larynx could explain the simplicity of treefrog calls, the larynges of euthanized males were activated with airflow. Laryngeal airflow, sound frequency, and sound intensity showed a positive direct relationship with the driving air pressure. While the natural calls of the studied species exhibit minimal frequency modulation, their larynges produced about an octave of frequency modulation in response to varying pulmonary pressure. Natural advertisement calls are produced near the higher extreme of frequency obtained in the laboratory and at a slightly higher intensity (6 dB). Natural calls also exhibit fewer harmonics than artificial ones, because the larynges were activated with the mouth of the animal open. The results revealed that treefrog larynges allow them to produce calls spanning a much greater range of frequencies than observed in nature; therefore, the simplicity of the calls is not due to a limited frequency range of laryngeal output. Low frequencies are produced at low intensities, however, and this could explain why treefrogs concentrate their calling at the high frequencies.

Attenuation of Earmuffs against Low Frequency Noise

1987 ◽  
Vol 6 (4) ◽  
pp. 167-174 ◽  
Author(s):  
Jukka Starck ◽  
Jussi Pekkarinen ◽  
Seppo Aatola
Keyword(s):  
Low Frequency ◽  
Peak Level ◽  
Standard Test ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Low Frequencies ◽  
Hearing Protectors ◽  
Noise Measurements ◽  
Attenuation Values ◽  
Very High

The standard test for hearing protectors cannot be applied to determine the attenuation values for low frequency noise or for noise consisting of high intensity impulses. Moreover, the aging of earmuffs and the use of spectacles may cause leakage which decreases attenuation mainly at low frequencies. To study the real attenuation of earmuffs, noise measurements were taken outside and inside the earmuffs of workers at industrial work places, and of military conscripts when shooting with different firearms. The effect of spectacles on the attenuation was measured under laboratory conditions. In industrial workplaces the average attenuation was 4 dB in the 63 and 125 Hz octave bands. For shooting noise the attenuation was found to be good for small calibre weapons but poor for large calibre weapons, which generate very high peak level impulses at low frequencies. Spectacles decreased earmuff attenuation by 9–11 dB.

scholarly journals Application of MEMS Microphone Array Technology to Airframe Noise Measurements

2005 ◽  
Author(s):  
William Humphreys ◽  
Qamar Shams ◽  
Sharon Graves ◽  
Bradley Sealey ◽  
Scott Bartram ◽  
...  
Keyword(s):  
Microphone Array ◽  
Airframe Noise ◽  
Array Technology ◽  
Mems Microphone ◽  
Noise Measurements

The lung-eardrum pathway in three treefrog and four dendrobatid frog species: some properties of sound transmission.

1994 ◽  
Vol 195 (1) ◽  
pp. 329-343 ◽  
Author(s):  
G Ehret ◽  
E Keilwerth ◽  
T Kamada
Keyword(s):  
High Frequency ◽  
Body Wall ◽  
Low Frequency ◽  
Sound Intensity ◽  
The Body ◽  
Response Curves ◽  
Low Frequencies ◽  
Best Response ◽  
Lateral Body ◽  
Frequency Components

Frequency-response curves of the tympanum and lateral body wall (lung area) were measured by laser Doppler vibrometry in three treefrog (Smilisca baudini, Hyla cinerea, Osteopilus septentrionalis) and four dendrobatid frog (Dendrobates tinctorius, D. histrionicus, Epipedobates tricolor, E. azureiventris) species. The high-frequency cut-off of the body wall response was always lower than that of the tympanum. The best response frequencies of the lateral body wall were lower than those of the tympanum in some species (S. baudini, O. septentrionalis, D. tinctorius), while in the others they were rather similar. Best tympanic frequencies and best body wall response frequencies tended to differ more with increasing body size. Stimulation of the tympanum by sound transfer through 3.14 mm2 areas of the lateral body wall showed that the lung-eardrum pathway can be in two states, depending on breathing activity within the lungs: 44% (in Smilisca), 39% (in Hyla) and 31% (in Osteopilus) of the eardrum vibrations were 2.5-8 times (8-18 dB) larger when the frogs were breathing with the lungs compared with non-breathing conditions. The vibration amplitudes of the tympanum and lateral body wall of the treefrogs followed the same dependence on sound intensity, only absolute amplitudes differed between species. Our results suggest that the lung-eardrum pathway attenuates high-frequency components of species-specific calls and enhances low-frequency components. In addition, an amplitude modulation is imposed on the low frequencies during the rhythm of breathing.

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