A refined four‐load method for the evaluation of in‐duct acoustic source characteristics

1997 ◽  
Vol 102 (5) ◽  
pp. 3181-3181
Author(s):  
Seung‐Ho Jang ◽  
Jeong‐Guon Ih
Keyword(s):  
Acoustic Source ◽  
Source Characteristics

scholarly journals Acoustic Source Data for Medium Speed IC-Engines

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Antti Hynninen ◽  
Raimo Turunen ◽  
Mats Åbom ◽  
Hans Bodén
Keyword(s):  
High Frequency ◽  
Internal Combustion Engines ◽  
Low Frequency ◽  
Acoustic Source ◽  
Ic Engine ◽  
Source Characteristics ◽  
Medium Speed ◽  
Source Data ◽  
Exhaust Noise ◽  
Ic Engines

Knowledge of the acoustic source characteristics of internal combustion engines (IC-engines) is of great importance when designing the exhaust duct system and its components to withstand the resulting dynamic loads and to reduce the exhaust noise emission. The goal of the present study is to numerically and experimentally investigate the medium speed IC-engine acoustic source characteristics, not only in the plane wave range but also in the high frequency range. The low frequency acoustic source characteristics were predicted by simulating the acoustic multiload measurements by using a one-dimensional process simulation code. The low frequency in-duct exhaust noise of a medium speed IC-engine can be quite accurately predicted. The high frequency source data is estimated by averaging the measured acoustic pressures with different methods; using the simple cross-spectra averaging method seems promising in this instance.

Perception of acoustic source characteristics: Walking sounds

1991 ◽  
Vol 90 (6) ◽  
pp. 3036-3049 ◽  
Author(s):  
Xiaofeng Li ◽  
Robert J. Logan ◽  
Richard E. Pastore
Keyword(s):  
Acoustic Source ◽  
Source Characteristics

scholarly journals Synthesis of Room Impulse Responses for Variable Source Characteristics

10.14311/1444 ◽  
2011 ◽  
Vol 51 (5) ◽  
Author(s):  
M. Kunkemoeller ◽  
P. Dietrich ◽  
M. Pollow
Keyword(s):  
Radiation Pattern ◽  
Musical Instrument ◽  
Lecture Hall ◽  
Acoustic Measurements ◽  
Impulse Responses ◽  
Acoustic Source ◽  
Characteristic Radiation ◽  
Sound Sources ◽  
Variable Source ◽  
Source Characteristics

Every acoustic source, e.g. a speaker, a musical instrument or a loudspeaker, generally has a frequency dependent characteristic radiation pattern, which is preeminent at higher frequencies. Room acoustic measurements nowadays only account for omnidirectional source characteristics. This motivates a measurement method that is capable of obtaining room impulse responses for these specific radiation patterns by using a superposition approach of several measurements with technically well-defined sound sources. We propose a method based on measurements with a 12-channel independentlydriven dodecahedron loudspeaker array rotated by an automatically controlled turntable.Radiation patterns can be efficiently described with the use of spherical harmonics representation. We propose a method that uses this representation for the spherical loudspeaker array used for the measurements and the target radiation pattern to be used for the synthesis.We show validating results for a deterministic test sound source inside in a small lecture hall.

Study on acoustic source characteristics of gas pipeline leakage

2019 ◽  
Vol 50 (3) ◽  
pp. 67-77 ◽  
Author(s):  
Han Baokun ◽  
Liu Xiyang ◽  
Liu Bing ◽  
Bao Huaiqian ◽  
Jiang Xiangguang
Keyword(s):  
Basic Principle ◽  
Engineering Application ◽  
Leak Detection ◽  
Acoustic Method ◽  
Gas Pipeline ◽  
Operating Conditions ◽  
Acoustic Energy ◽  
Acoustic Source ◽  
Source Characteristics ◽  
Simulation Results

The characteristics of acoustic source of gas pipeline leakage determine the accuracy and adaptability of leak detection for gas pipelines based on acoustic method. In order to explore the characteristics of leakage acoustic source of gas pipeline, a physical model of gas pipeline leakage was developed. Initially, generation mechanism of acoustic source of gas pipeline leakage is studied in order to identify the basic principle of leak detection of gas pipeline based on acoustic method. After that, the simulation model is developed according to the basic principle of aeroacoustics, the flow field, and sound source characteristics of the gas pipeline leakage. Then, the experimental platform for the study on acoustic source characteristics of gas pipeline leakage is set up using the basic principle of the leak detection based on acoustic method and simulation results. The characteristics of acoustic source of leakage are obtained through experiments. Finally, the simulation and experimental results of acoustic source of leakage under different operating conditions are compared, and the accuracy of the simulation results is verified, which provides a theoretical basis for the engineering application of leak detection for gas pipeline based on acoustic method. The results show that the acoustic source of gas pipeline leakage is mainly quadrupole source and the leakage acoustic energy is mainly in the range of less than 100 Hz. The mean value of sound pressure level is increased with the pressure in pipeline and the size of leak aperture.

Acoustic Measurements of Men’s and Women’s Voices

1990 ◽  
Vol 33 (4) ◽  
pp. 761-775 ◽  
Author(s):  
Susan Nittrouer ◽  
Richard S. McGowan ◽  
Paul H. Milenkovic ◽  
Donna Beehler
Keyword(s):  
Fundamental Frequency ◽  
Underlying Mechanism ◽  
Early Morning ◽  
Acoustic Measurements ◽  
Acoustic Source ◽  
Signal To Noise ◽  
Men And Women ◽  
Women's Voices ◽  
Acoustic Measures ◽  
Source Characteristics

Several acoustic measures of laryngeal activity were made on adult speech to help answer two questions left unresolved by previous work: (1) how each measure varies, if at all, with phonetic structure, and (2) what aspect of laryngeal activity each measure specifies. Speech samples of 15 syllables (three vowels in five prevocalic consonantal contexts) were collected from men and women at two times of the day (early morning and late afternoon). Eight measurements were made, mainly on slices extracted from the middle of the vocalic portions, and inferential and correlational statistics were applied to these measures. Results of the inferential tests indicated differences between men and women in how laryngeal adjustments are made, affecting relative amounts of vocal jitter and spectral tilt of the voicing source. In addition, the voicing and manner characteristics of the prevocalic consonant were found to affect fundamental frequency, cycle-to-cycle perturbations, and amount of aspiration noise. To a lesser extent, vowel height and front/back tongue placement also affected these acoustic source characteristics. Results of the correlational tests showed that different laryngeal mechanisms contributed differentially to signal-to-noise ratios for men and women, and these mechanisms were more greatly affected by fundamental frequency for men’s samples. Finally, various acoustic measures of laryngeal noise were found to be related to the same underlying mechanism.

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