scholarly journals Sound Enhancement of Orthotropic Sound Radiation Plates Using Line Loads and Considering Resonance Characteristics

Acoustics ◽  
2021 ◽  
Vol 3 (4) ◽  
pp. 642-666
Author(s):  
Ahmad Nayan ◽  
Tai Yan Kam
Keyword(s):  
Sound Pressure Level ◽  
Orthotropic Plate ◽  
Sound Pressure ◽  
Acoustic Analysis ◽  
Sound Radiation ◽  
Pressure Level ◽  
Level Curve ◽  
Orthotropic Plates ◽  
Elastically Restrained ◽  
Line Loads

A new vibro-acoustic method is presented to analyze the sound radiation behavior of orthotropic panel-form sound radiators using strip-type exciters to exert line loads to the panels for sound radiation. The simple first-order shear deformation theory together with the Ritz method is used to formulate the proposed method that makes the vibro-acoustic analysis of elastically restrained stiffened orthotropic plates more computationally efficient than the methods formulated on the basis of the other shear deformation theories. An elastically restrained orthotropic plate consisting of two parallel strip-type exciters was tested to measure the experimental sound pressure level curve for validating the effectiveness and accuracy of the proposed method. The resonance characteristics (natural frequency and mode shape) detrimental to sound radiation are identified in the vibro-acoustic analysis of the orthotropic plate. For any orthotropic sound radiation plate, based on the detrimental mode shapes, a practical procedure is presented to design the line load locations on the plate to suppress the major sound pressure level dips for enhancing the smoothness of the plate sound pressure level curve. For illustration, the sound radiation enhancement of orthotropic plates with different fiber orientations for aspect ratios equal to 3, 2, and 1 subjected to one or two line loads is conducted using the proposed procedure. The results for the cases with two line loads perpendicular to the fiber direction and located at the nodal lines of the major detrimental mode shape may find applications in designing orthotropic panel-form speakers with relatively smooth sound pressure level curves.

scholarly journals Immediate effects of cervical stimulation and diaphragmatic release on vocal production

2020 ◽  
Vol 33 ◽  
Author(s):  
Érika Corrêa Machado ◽  
Letícia Fernandez Frigo ◽  
Fernanda Anversa Bresolin ◽  
Joziane Padilha de Moraes Lima ◽  
Carla Aparecida Cielob
Keyword(s):  
Fundamental Frequency ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Acoustic Analysis ◽  
Cervical Vertebra ◽  
Pressure Level ◽  
Abdominal Muscles ◽  
Adult Women ◽  
Maximum Phonation Time ◽  
Cervical Stimulation

Abstract Introduction: The voice is heavily influenced by breathing and abdominal muscles. Objective: To verify the immediate effects of cervical stimulation and diaphragmatic release on the respiratory and phonatory function of adult women with no vocal complaints. Method: Relaxation maneuvers and eccentric work of the diaphragm were performed together with articulatory maneuver of the third cervical vertebra. Twenty-four women without vocal complaints, aged between 18 and 35 years were part of the intervention. All volunteers were submitted to an evaluation of respiratory muscle strength, maximum phonation time of the vowel /a/, sound pressure level and acoustic vocal analysis, before and after physiotherapeutic intervention. Statistical analysis consisted of the Student's t-test for independent samples and Spearman's correlation. Significance level was set at 5%. Results: There was a significant increase in the maximum phonation time of the vowel /a/ and in the modal sound pressure level. Regarding the acoustic analysis, there was a reduction in the standard deviation values of the fundamental frequency; in the smoothed pitch disturbance quotient; and in the fundamental frequency and amplitude variations. Conclusion: Cervical stimulation and diaphragmatic release improved vocal quality regarding duration of emission, sound pressure, and stability and noise of the glottic signal.

Active Control of Structural Sound Radiation in an Acoustic Enclosure Using Distributed Point Force Actuators

2014 ◽  
Vol 1082 ◽  
pp. 517-520
Author(s):  
Da Lin Chen ◽  
Nan Chen
Keyword(s):  
Active Control ◽  
Sound Pressure Level ◽  
Cooperative Control ◽  
Sound Pressure ◽  
Control Method ◽  
Sound Radiation ◽  
Sound Field ◽  
Pressure Level ◽  
Point Force ◽  
Flexible Plates

This paper demonstrates an investigation about the active control of sound radiation in the enclosure cavity consists of two flexible plates. One of the flexible plates is driven by a point force to generate the primary sound field in the cavity, and using some point forces which are located at different locations on the receiving plate to suppressing the panel vibration and then to minimum the cavity sound pressure level (SPL); meanwhile some actuators are located on the other panel surfaces to reduce the sound pressure level at some frequencies that can’t be well reduced by only effect on one panel. The better result shows the possibility of applying distributed cooperative control method to the structural-acoustic coupled system.

Vibro-Acoustic Analysis of a Heavy Duty Truck Cabin

2014 ◽  
Author(s):  
Hakan Yenerer ◽  
Andrei Cristian Stan ◽  
Polat Sendur ◽  
Ipek Basdogan
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Acoustic Analysis ◽  
Element Model ◽  
Pressure Level ◽  
Heavy Duty ◽  
Operational Conditions ◽  
Vehicle Cabin ◽  
Heavy Duty Truck ◽  
Internal Forces

Automotive manufacturers invest a lot of effort and money to enhance the vibro-acoustic performance of their products. In a complex dynamic system such as a truck cabin, the enhancement effort may be very difficult and time-consuming if only the ‘trial and error’ method is used without prior knowledge about the noise contributors. The purpose of this paper is to identify the most influential noise radiating panel in a passenger cabin compartment of a heavy duty truck. The noise inside the vehicle cabin originates from various sources and travels through many pathways. The first step of sound quality refinement is to find the pathways and corresponding operational internal forces. Operational acceleration responses and frequency response functions (FRFs) are measured on a prototype truck to determine the excitation forces while engine is running in operational conditions. Once these internal forces are identified using the experimental force identification (FI) technique, they are utilized to predict the total sound pressure level inside the cabin and also perform the panel acoustic contribution analysis (PACA) to determine the most problematic panel of the cabin. A coupled vibro-acoustic finite element model (FEM) is used to predict the sound pressure level inside the cabin. Sound pressure levels at the driver’s and passenger’s right and left ears are determined numerically for excitation coming from the cabin mounts ranging between 20–200 Hz. When the most noise radiating panel is identified, it can be redesigned to improve the sound pressure level inside the cabin.

Decentralized robust control of a vehicle’s interior sound field

2020 ◽  
Vol 26 (19-20) ◽  
pp. 1815-1823
Author(s):  
Golsa Ghanati ◽  
Shahram Azadi
Keyword(s):  
Sound Pressure Level ◽  
Control Strategy ◽  
Sound Pressure ◽  
Acoustic Analysis ◽  
Sound Field ◽  
Control Unit ◽  
Pressure Level ◽  
Decentralized Robust Control ◽  
Feedback Control Strategy ◽  
Head Positions

In this article, a decentralized strategy is applied for active control of sound inside the automobile cabin by considering the uncertainty caused by the movement of the occupants. A coupled structural-acoustic analysis is done on the simplified geometry of the automobile cabin with passengers by the finite element method. The uncertainty caused by changes in the occupants’ head positions and angles is also considered. Then, a decentralized robust feedback control strategy is proposed to reduce the sound pressure level in the ears of all the occupants using the H∞ method for each individual control unit by considering the unstructured uncertainty of the plant. The efficiency of the proposed control strategy in minimizing the sound pressure level caused by the structural disturbance on the firewall panel is investigated.

Vibro-Acoustic Design Optimization Study to Improve the Sound Pressure Level Inside the Passenger Cabin

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Erdem Yuksel ◽  
Gulsen Kamci ◽  
Ipek Basdogan
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Performance Metrics ◽  
Acoustic Analysis ◽  
Pressure Level ◽  
Interior Noise ◽  
Design Parameters ◽  
Sound Pressure Levels ◽  
Passenger Cabin ◽  
Element Method

The interior noise inside the passenger cabin of automobiles can be classified as structure-borne or airborne. In this study, we investigate the structure-borne noise, which is mainly caused by the vibrating panels enclosing the vehicle. Excitation coming from the engine causes the panels to vibrate at their resonance frequencies. These vibrating panels cause a change in the sound pressure level within the passenger cabin, and consequently generating an undesirable booming noise. It is critical to understand the dynamics of the vehicle, and more importantly, how it interacts with the air inside the cabin. Two methodologies were used by coupling them to predict the sound pressure level inside the passenger cabin of a commercial vehicle. The Finite Element Method (FEM) was used for the structural analysis of the vehicle, and the Boundary Element Method (BEM) was integrated with the results obtained from FEM for the acoustic analysis of the cabin. The adopted FEM-BEM approach can be utilized to predict the sound pressure level inside the passenger cabin, and also to determine the contribution of each radiating panel to the interior noise level. The design parameters of the most influential radiating panels (i.e., thickness) can then be optimized to reduce the interior noise based on the three performance metrics. A structured parametric study, based on techniques from the field of industrial design of experiments (DOE) was employed to understand the relationship between the design parameters and the performance metrics. A DOE study was performed for each metric to identify the components that have the highest contribution to the sound pressure levels inside the cabin. For each run, the vibro-acoustic analysis of the system is performed, the sound pressure levels are calculated as a function of engine speed and then the performance metrics are calculated. The highest contributors (design parameters) to each performance metric are identified and regression models are built to be used for optimization studies. Then, preliminary optimization runs are employed to improve the interior sound pressure levels by finding the optimum configurations for the panel thicknesses. Our results show that the methodology developed in this study can be effectively used for improving the design of the panels to reduce interior noise when the vibro-acoustic response is chosen as the performance criteria.

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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