Modeling the Sound Source of an Intake and Predicting the Intake Sound Pressure Level for a Motorcycle

2003 ◽  
Author(s):  
Hideki Kido ◽  
Hiroyuki Kuwahara ◽  
Eike Brechlin ◽  
Rene Boonen
Keyword(s):  
Sound Pressure Level ◽  
Sound Source ◽  
Sound Pressure ◽  
Pressure Level

scholarly journals Noise Reduction Mechanisms of an Airfoil with Trailing Edge Serrations at Low Mach Number

2019 ◽  
Vol 9 (18) ◽  
pp. 3784 ◽  
Author(s):  
Hui Tang ◽  
Yulong Lei ◽  
Yao Fu
Keyword(s):  
Noise Reduction ◽  
Sound Pressure Level ◽  
Sound Source ◽  
Sound Pressure ◽  
Pressure Level ◽  
Source Distribution ◽  
Noise Mitigation ◽  
Trailing Edge ◽  
Trailing Edge Noise ◽  
Trailing Edge Serrations

Trailing-edge serrations have proven to be valid applications of trailing edge noise mitigation for an airfoil, while the physical noise reduction mechanism has not been adequately studied. We performed simulations employing Large-eddy simulation and the Lighthill–Curle method to reveal the variation in the hydrodynamic field and sound source due to the trailing edge serrations. The grid resolution and computational results were validated against experimental data. The simulation results show that: the trailing edge serrations impede the growth of spanwise vortices and promote the development of streamwise vortices near the trailing edge and the wake; the velocity fluctuations in the vertical cross-section of the streamwise direction near the trailing edge are reduced for the serrated airfoil, thereby obviously reducing the strength of the pressure fluctuations near the trailing edge; and the trailing edge serrations decrease the distribution of the sound source near the trailing edge and reduce the local peak value of sound pressure level in a specific frequency range as well as the overall sound pressure level. Moreover, we observed that, in the flow around the NACA0012 airfoil, the location where the strong sound source distribution begins to appear is in good agreement with the location where the separated boundary layer reattaches. It is therefore effective to reduce trailing edge noise by applying serrations on the upstream of the reattachment point.

Single-unit selectivity to azimuthal direction and sound pressure level of noise bursts in cat high-frequency primary auditory cortex

1990 ◽  
Vol 63 (6) ◽  
pp. 1448-1466 ◽  
Author(s):  
T. J. Imig ◽  
W. A. Irons ◽  
F. R. Samson
Keyword(s):  
Auditory Cortex ◽  
Sound Pressure Level ◽  
Sound Source ◽  
Single Unit ◽  
Sound Pressure ◽  
Free Field ◽  
Sound Field ◽  
Primary Auditory Cortex ◽  
Pressure Level ◽  
Broadband Noise

1. The azimuth and sound pressure level (SPL) selectivities of single-unit responses recorded in primary auditory cortex of barbiturate-anesthetized cats were studied by the use of broadband noise bursts delivered in the free field from a moveable loud-speaker. The experiments were carried out with cats located inside a quasianechoic sound-isolation chamber. We studied 71 units with relatively stable response properties. All units were located in the frequency representation between 5.8 and 31 kHz. The data obtained for each unit were displayed as an azimuth-level response area, a contour plot that displays the distribution of response magnitude as a joint function of SPL and azimuth at 0 degrees elevation. From these, azimuth and level functions were obtained to derive descriptors of azimuth and level selectivity. 2. Sensitivity to sound-source azimuth was assessed from the modulation of the average azimuth function (average of azimuth functions obtained to each SPL of noise that was presented) for each unit. The sample was arbitrarily divided into a high-directionality (HD) group (66%) whose average azimuth functions had modulation values of greater than or equal to 75% and a low-directionality (LD) group (34%). The distinction between HD and LD groups was made so that we could analyze the characteristics of units likely to be involved in the representation of sound-source azimuth. 3. There is an overrepresentation of the contralateral sound field and the midline in the sample of HD units. The preferred sector for each unit was defined as the range of azimuths within the frontal sound field throughout which unit response was greater than or equal to 75% of maximum. Each unit was classified as either midline preferring (17%, the midpoint of the preferred sector, i.e., best azimuth, was located within 5 degrees of the midline), contralateral preferring (60%), or ipsilateral preferring (23%). The ratio of contralateral- to ipsilateral-preferring units was 2.5:1. A higher proportion of units had best azimuths located in the 10 degrees sector centered on the midline than in any other 10 degrees sector of the frontal sound field. 4. In one animal, recordings were obtained at seven closely spaced sites in layer IV from single- and multiunit responses, which were narrowly tuned to both azimuth and SPL. The units located along a 1-mm length of an isofrequency strip were tuned to similar frequencies and SPLs but had five distinctly different directional preferences distributed throughout the entire frontal sound field.(ABSTRACT TRUNCATED AT 400 WORDS)

Experimental Visualization of Sound Pressure Level and Vibration Around a Soundproof Barrier

2011 ◽  
Author(s):  
Fumio Shimizu ◽  
Kazuhiro Tanaka ◽  
Koji Yamamoto ◽  
Hiroshi Shigefuji
Keyword(s):  
Noise Reduction ◽  
Sound Pressure Level ◽  
Sound Source ◽  
Sound Pressure ◽  
Pressure Level ◽  
Heat Radiation ◽  
Sound Insulation ◽  
Vibration Displacement ◽  
The One ◽  
The Relationship

The noise and vibration control are the one of important issues. A soundproof barrier, which covers a sound source with sound absorbing materials, is very useful for the noise reduction. When large noise and high temperature heat emit from the sound source, we must also consider the heat radiation as well as the noise reduction. The purpose of the present study is to investigate the relationship between sound pressure level and vibration on a soundproof barrier around a sound source. The effect of heat radiation hole on the sound insulation performance of the soundproof barrier is also investigated. The sound pressure level and the vibration displacement were similarly distributed on the surface of the barrier. Therefore, the vibration of the barrier was strongly influenced to the sound pressure level of the transmitted sound.

Sound of Linear Guideway Type Recirculating Linear Ball Bearings

1999 ◽  
Vol 121 (4) ◽  
pp. 678-685 ◽  
Author(s):  
Hiroyuki Ohta
Keyword(s):  
Sound Pressure Level ◽  
Sound Source ◽  
Sound Pressure ◽  
Natural Vibration ◽  
Ball Bearing ◽  
Pressure Level ◽  
Linear Velocity ◽  
Ball Bearings ◽  
Rate Of Increase ◽  
Measurement Results

The sound characteristics of linear guideway type (LGT) recirculating linear ball bearing driven at a constant linear velocity was studied. The measurement results of the sound characteristics showed that the LGT recirculating linear ball bearing has a sound property between line sound source and point sound source, and the measured overall sound pressure level increases with increasing the linear velocity of the carriage. The rate of increase of the overall sound pressure level to the linear velocity was analyzed combining the deduction of Yamada et al. and the results of previous studies on the collision sound. The results of this analysis match roughly the rate of increase of the measured overall sound pressure level to the linear velocity. We also observed the main peaks in the sound spectra of the LGT recirculating linear ball bearing itself. As a result, it was made clear that the main peaks are caused by the lower rolling natural vibration of the carriage, the pitching natural vibration of the carriage, and the vertical natural vibration of the carriage. In addition, the frequencies of the main peaks can be estimated by using presented expressions fRL, fP, and fv.

Contributions of Voice and Nonverbal Communication to Perceived Masculinity–Femininity for Cisgender and Transgender Communicators

2020 ◽  
Vol 63 (4) ◽  
pp. 931-947
Author(s):  
Teresa L. D. Hardy ◽  
Carol A. Boliek ◽  
Daniel Aalto ◽  
Justin Lewicke ◽  
Kristopher Wells ◽  
...  
Keyword(s):  
Fundamental Frequency ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Vocal Tract ◽  
Presentation Mode ◽  
Pressure Level ◽  
Presentation Modes ◽  
Audiovisual Stimuli ◽  
Vocal Tract Resonance ◽  
Point Light

Purpose The purpose of this study was twofold: (a) to identify a set of communication-based predictors (including both acoustic and gestural variables) of masculinity–femininity ratings and (b) to explore differences in ratings between audio and audiovisual presentation modes for transgender and cisgender communicators. Method The voices and gestures of a group of cisgender men and women ( n = 10 of each) and transgender women ( n = 20) communicators were recorded while they recounted the story of a cartoon using acoustic and motion capture recording systems. A total of 17 acoustic and gestural variables were measured from these recordings. A group of observers ( n = 20) rated each communicator's masculinity–femininity based on 30- to 45-s samples of the cartoon description presented in three modes: audio, visual, and audio visual. Visual and audiovisual stimuli contained point light displays standardized for size. Ratings were made using a direct magnitude estimation scale without modulus. Communication-based predictors of masculinity–femininity ratings were identified using multiple regression, and analysis of variance was used to determine the effect of presentation mode on perceptual ratings. Results Fundamental frequency, average vowel formant, and sound pressure level were identified as significant predictors of masculinity–femininity ratings for these communicators. Communicators were rated significantly more feminine in the audio than the audiovisual mode and unreliably in the visual-only mode. Conclusions Both study purposes were met. Results support continued emphasis on fundamental frequency and vocal tract resonance in voice and communication modification training with transgender individuals and provide evidence for the potential benefit of modifying sound pressure level, especially when a masculine presentation is desired.

Case study: Theoretical calculation model and variable condition analysis research on the water-splashing noise for natural draft wet cooling towers

2020 ◽  
Vol 68 (2) ◽  
pp. 137-145
Author(s):  
Yang Zhouo ◽  
Ming Gao ◽  
Suoying He ◽  
Yuetao Shi ◽  
Fengzhong Sun
Keyword(s):  
Theoretical Model ◽  
Sound Pressure Level ◽  
Water Droplet ◽  
Water Distribution ◽  
Sound Pressure ◽  
Cooling Tower ◽  
Distribution Patterns ◽  
Calculation Model ◽  
Pressure Level ◽  
Cooling Towers

Based on the basic theory of water droplets impact noise, the generation mechanism and calculation model of the water-splashing noise for natural draft wet cooling towers were established in this study, and then by means of the custom software, the water-splashing noise was studied under different water droplet diameters and water-spraying densities as well as partition water distribution patterns conditions. Comparedwith the water-splashing noise of the field test, the average difference of the theoretical and the measured value is 0.82 dB, which validates the accuracy of the established theoretical model. The results based on theoretical model showed that, when the water droplet diameters are smaller in cooling tower, the attenuation of total sound pressure level of the water-splashing noise is greater. From 0 m to 8 m away from the cooling tower, the sound pressure level of the watersplashing noise of 3 mm and 6 mm water droplets decreases by 8.20 dB and 4.36 dB, respectively. Additionally, when the water-spraying density becomes twice of the designed value, the sound pressure level of water-splashing noise all increases by 3.01 dB for the cooling towers of 300 MW, 600 MW and 1000 MW units. Finally, under the partition water distribution patterns, the change of the sound pressure level is small. For the R s/2 and Rs/3 partition radius (Rs is the radius of water-spraying area), when the water-spraying density ratio between the outer and inner zone increases from 1 to 3, the sound pressure level of water-splashing noise increases by 0.7 dB and 0.3 dB, respectively.

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