Tae-Gyoung Kim, Suk-Yoon Hong, Jee-hun Song, H. Kwon, Sung-Hooin Kim
Noise analysis from heating, ventilation and air conditioning (HVAC) elements in ship cabins is needed to satisfy the strict noise regulation for the ship cabin, and it is very important for their effects to be evaluated in the early stage of design. In this paper, a direct acoustic energy flow analysis (DAEFA) model is presented for the noise analysis of the ship cabin to reflect direct fields of the sources from an HVAC element. Total acoustic fields are considered by deriving the fundamental solution of the energy flow model for direct and reverberant fields in a closed space. Sound propagation in the direct field is implemented using the geometrical acoustics concept, and noise sources introduced into the reverberant sound fields are considered by using the relationship between direct fields and the closed space boundaries. For cabin noise analysis using DAEFA, interior boundaries of the cabin are discretized, and boundary integral formulations for each field are integrated. Noise analysis is performed for various cases with the DAEFA model to minimize cabin noise. The optimal design derived through the analysis was applied to an actual ship, and cabin noise measurement was conducted onboard the applied ship. Comparison of the analysis and measurement results confirms the effectiveness of the proposed design.
{"title":"Development of direct acoustic energy flow analysis (DAEFA) for ship cabin noise in the medium-to-high frequency range","authors":"Tae-Gyoung Kim, Suk-Yoon Hong, Jee-hun Song, H. Kwon, Sung-Hooin Kim","doi":"10.3397/1/377027","DOIUrl":"https://doi.org/10.3397/1/377027","url":null,"abstract":"Noise analysis from heating, ventilation and air conditioning (HVAC) elements in ship cabins is needed to satisfy the strict noise regulation for the ship cabin, and it is very important for their effects to be evaluated in the early stage of design. In this paper, a direct acoustic\u0000 energy flow analysis (DAEFA) model is presented for the noise analysis of the ship cabin to reflect direct fields of the sources from an HVAC element. Total acoustic fields are considered by deriving the fundamental solution of the energy flow model for direct and reverberant fields in a closed\u0000 space. Sound propagation in the direct field is implemented using the geometrical acoustics concept, and noise sources introduced into the reverberant sound fields are considered by using the relationship between direct fields and the closed space boundaries. For cabin noise analysis using\u0000 DAEFA, interior boundaries of the cabin are discretized, and boundary integral formulations for each field are integrated. Noise analysis is performed for various cases with the DAEFA model to minimize cabin noise. The optimal design derived through the analysis was applied to an actual ship,\u0000 and cabin noise measurement was conducted onboard the applied ship. Comparison of the analysis and measurement results confirms the effectiveness of the proposed design.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47719396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Z. Hou, Tengfei Si, Shiqiang Zhang, Zhijun Zhang, Jiyu Sun
Exhaust noise produced by internal combustion engines is one of the main problems of vehicle noise, and exhaust mufflers can significantly improve this problem. In fact, the sound waves inside the exhaust muffler will cause the muffler shell to vibrate, causing the muffler to produce shell radiation noise. Therefore, it is necessary to carry out the acoustic-structure coupling analysis of the muffler. This paper improved the design of a prototype straight-through perforated pipe-resistant muffler (design A) and designed a straight-through perforated pipe-resistant muffler with a corrugated lining (design B). Structural modal analysis, acoustic modal analysis, and transmission loss analysis of the two mufflers were carried out. The coupling of the acoustic cavity and structure was considered, and the radiation noise of two kinds of resistant mufflers was comparatively analyzed by the direct-boundary-element method. The acoustic radiation of two kinds of resistant mufflers was studied. The pressure loss of the two kinds of mufflers was studied by aerodynamic analysis. The results suggested that the design B muffler effectively improved the noise reduction performance of the prototype muffler, reduced the vibration displacement amplitude of the shell, and reduced the sound power level of the design A muffler.
{"title":"Case study: Analysis of acoustic-structure coupling noise characteristics of the exhaust muffler of an internal combustion engine","authors":"Z. Hou, Tengfei Si, Shiqiang Zhang, Zhijun Zhang, Jiyu Sun","doi":"10.3397/1/377028","DOIUrl":"https://doi.org/10.3397/1/377028","url":null,"abstract":"Exhaust noise produced by internal combustion engines is one of the main problems of vehicle noise, and exhaust mufflers can significantly improve this problem. In fact, the sound waves inside the exhaust muffler will cause the muffler shell to vibrate, causing the muffler to produce\u0000 shell radiation noise. Therefore, it is necessary to carry out the acoustic-structure coupling analysis of the muffler. This paper improved the design of a prototype straight-through perforated pipe-resistant muffler (design A) and designed a straight-through perforated pipe-resistant muffler\u0000 with a corrugated lining (design B). Structural modal analysis, acoustic modal analysis, and transmission loss analysis of the two mufflers were carried out. The coupling of the acoustic cavity and structure was considered, and the radiation noise of two kinds of resistant mufflers was comparatively\u0000 analyzed by the direct-boundary-element method. The acoustic radiation of two kinds of resistant mufflers was studied. The pressure loss of the two kinds of mufflers was studied by aerodynamic analysis. The results suggested that the design B muffler effectively improved the noise reduction\u0000 performance of the prototype muffler, reduced the vibration displacement amplitude of the shell, and reduced the sound power level of the design A muffler.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45856855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fengfeng Bie, Yue Guo, Sheng Gu, Gang Yang, Mingjun Pang
Accurate buried pipeline state recognition based on acoustic signal is a difficult and important issue. This paper proposes a feature extraction method based on acoustic signal frame and principal component analysis (PCA) for condition monitoring in pipes. This method makes use of the property of nonstationary and multivariate data decomposition scales of pipeline acoustic signal. Signal framing is processed on the collected acoustic signals so that the signal frame series is obtained. Then, the sound pressure level of each frame signal is extracted, and the feature vector of the total sound pressure level is established. The PCA method is applied to optimize the extracted feature vector set for detecting the feature parameters. The acoustic signals related to different operating conditions of a pipeline are identified with the support vector machine. Research on a series of experiments shows that the proposed method for acoustic signal analysis can perform effectively for robust feature extraction and pipeline state identification.
{"title":"Research on pipeline state recognition method based on acoustic signal frame PCA","authors":"Fengfeng Bie, Yue Guo, Sheng Gu, Gang Yang, Mingjun Pang","doi":"10.3397/1/377029","DOIUrl":"https://doi.org/10.3397/1/377029","url":null,"abstract":"Accurate buried pipeline state recognition based on acoustic signal is a difficult and important issue. This paper proposes a feature extraction method based on acoustic signal frame and principal component analysis (PCA) for condition monitoring in pipes. This method makes use of the\u0000 property of nonstationary and multivariate data decomposition scales of pipeline acoustic signal. Signal framing is processed on the collected acoustic signals so that the signal frame series is obtained. Then, the sound pressure level of each frame signal is extracted, and the feature vector\u0000 of the total sound pressure level is established. The PCA method is applied to optimize the extracted feature vector set for detecting the feature parameters. The acoustic signals related to different operating conditions of a pipeline are identified with the support vector machine. Research\u0000 on a series of experiments shows that the proposed method for acoustic signal analysis can perform effectively for robust feature extraction and pipeline state identification.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47839485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Simple revolving clearance pin and bush joint is standard and is widely used in machines and mechanisms. Clearance is necessary for rotational mobility of the joint parts, but it may lead to contact loss, which produces noise. To avoid the contact loss, it is necessary to ensure equality between the accelerations of the driver and the driven parts of the joint. In the case of a driver pin inside a bush as a free-driven part of the clearance joint, the acceleration of the bush in the vertical direction is limited to gravity. Therefore, if the exciting pin vibrates with downward acceleration more than the gravity, the contact loss will occur. As a solution, the acceleration of the free part was increased by a symmetric set of springs and a wire. To predict the contact condition, a set of dynamic equilibrium equations was developed and used to obtain the minimum spring stiffness and preload. Simulation and experimental results verified the concept of the contact loss and proved the effectiveness of using proper spring on noise reduction. Theoretical results show that with a sufficient spring preload, it is possible to use an arbitrary stiffness down to a limit even at relatively large accelerations. According to the acoustic tests, the noise picks were attenuated considerably, and the noise level was reduced to the background noise level after using proper springs.
{"title":"Theoretical and experimental investigations for noise reduction of clearance joints in vertical vibrations","authors":"Milad Sadri, M. Forouzan","doi":"10.3397/1/377026","DOIUrl":"https://doi.org/10.3397/1/377026","url":null,"abstract":"Simple revolving clearance pin and bush joint is standard and is widely used in machines and mechanisms. Clearance is necessary for rotational mobility of the joint parts, but it may lead to contact loss, which produces noise. To avoid the contact loss, it is necessary to ensure equality\u0000 between the accelerations of the driver and the driven parts of the joint. In the case of a driver pin inside a bush as a free-driven part of the clearance joint, the acceleration of the bush in the vertical direction is limited to gravity. Therefore, if the exciting pin vibrates with downward\u0000 acceleration more than the gravity, the contact loss will occur. As a solution, the acceleration of the free part was increased by a symmetric set of springs and a wire. To predict the contact condition, a set of dynamic equilibrium equations was developed and used to obtain the minimum spring\u0000 stiffness and preload. Simulation and experimental results verified the concept of the contact loss and proved the effectiveness of using proper spring on noise reduction. Theoretical results show that with a sufficient spring preload, it is possible to use an arbitrary stiffness down to a\u0000 limit even at relatively large accelerations. According to the acoustic tests, the noise picks were attenuated considerably, and the noise level was reduced to the background noise level after using proper springs.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44668054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shi-long Wang, Bo Hu, Song Li, Lanyue Zhang, Jie Shi
Air cavities with particular arrangements embedded in elastic layers are generally used as anechoic coatings. In this paper, an idea of cavity numbers with gradient changes is introduced in a soft elastic medium that comprises periodical cylindrical cavities to enhance the low-frequency absorption capacity effectively. The presented model provides a sound absorption coefficient that is higher than 0.5 in the frequency ranges of 75 to 95 Hz and 380 to 720 Hz. Thus, validating the idea can effectively enhance the low-frequency absorption capacity compared with those in previous literature. Analytical results based on effective medium approximation theory are compared with those obtained numerically using the finite element method. These results indicate that the invalidity of the analytical model is due to the coupling between cavities under low lattice constant. Power density dissipation and displacement vectors are plotted to study sound absorption mechanism, thereby showing that the dissipated energy is mainly resulted from the multiple-scattering effect. The scattering between cavities induces the transverse wave caused by the wave mode conversion dissipates in the elastic medium and results in sound absorption. Simulation results show that the absorption peaks can be effectively manipulated by tuning the gradient profile of the cavity numbers. The proposed model is then verified by the corresponding experiment. Results obtained numerically and experimentally are agreed well, and its feasibility is verified. The presented model would offer a new approach for the metamaterial design on low-frequency broadband sound absorption and could have potential applications on the design of anechoic coatings.
{"title":"Acoustic performance of cavities with gradient changes of cavity numbers under low lattice constant in a soft elastic medium","authors":"Shi-long Wang, Bo Hu, Song Li, Lanyue Zhang, Jie Shi","doi":"10.3397/1/377023","DOIUrl":"https://doi.org/10.3397/1/377023","url":null,"abstract":"Air cavities with particular arrangements embedded in elastic layers are generally used as anechoic coatings. In this paper, an idea of cavity numbers with gradient changes is introduced in a soft elastic medium that comprises periodical cylindrical cavities to enhance the low-frequency\u0000 absorption capacity effectively. The presented model provides a sound absorption coefficient that is higher than 0.5 in the frequency ranges of 75 to 95 Hz and 380 to 720 Hz. Thus, validating the idea can effectively enhance the low-frequency absorption capacity compared with those in previous\u0000 literature. Analytical results based on effective medium approximation theory are compared with those obtained numerically using the finite element method. These results indicate that the invalidity of the analytical model is due to the coupling between cavities under low lattice constant.\u0000 Power density dissipation and displacement vectors are plotted to study sound absorption mechanism, thereby showing that the dissipated energy is mainly resulted from the multiple-scattering effect. The scattering between cavities induces the transverse wave caused by the wave mode conversion\u0000 dissipates in the elastic medium and results in sound absorption. Simulation results show that the absorption peaks can be effectively manipulated by tuning the gradient profile of the cavity numbers. The proposed model is then verified by the corresponding experiment. Results obtained numerically\u0000 and experimentally are agreed well, and its feasibility is verified. The presented model would offer a new approach for the metamaterial design on low-frequency broadband sound absorption and could have potential applications on the design of anechoic coatings.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46286840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Vosoughi, I. Alimohammadi, A. Hosseini, Zhaleh Sedghi Noushabadi
The aim of this study is to determine the relationship between knowledge and attitude toward using hearing protection devices as a safe behavior. Also, it is intended to analyze the role of individuals and job characteristics on using earplugs or earmuffs. In this study, workers participated from 16 printing industries located in five areas of Tehran province and completed the questionnaire knowledge, attitude, and practice (KAP) about hearing conservation. Noise measurement was performed based on participants' tasks. With increasing attitude, practice improved (P = 0.001). The results revealed that positive attitude led to improved practice of workers in hearing conservation (r = 0.172; P < 0.001), and with increasing knowledge, negative attitude diminished (P=0.014). The results indicated that awareness is correlated with attitude, and attitude could directly affect the behavior. Thus, awareness as an intermediate or primary factor might play an important role in developing safe behaviors.
{"title":"Case study: Knowledge, attitude, and practice (KAP) regarding hearing protection: A case study among offset printing industry workers in Tehran province","authors":"S. Vosoughi, I. Alimohammadi, A. Hosseini, Zhaleh Sedghi Noushabadi","doi":"10.3397/1/377021","DOIUrl":"https://doi.org/10.3397/1/377021","url":null,"abstract":"The aim of this study is to determine the relationship between knowledge and attitude toward using hearing protection devices as a safe behavior. Also, it is intended to analyze the role of individuals and job characteristics on using earplugs or earmuffs. In this study, workers participated\u0000 from 16 printing industries located in five areas of Tehran province and completed the questionnaire knowledge, attitude, and practice (KAP) about hearing conservation. Noise measurement was performed based on participants' tasks. With increasing attitude, practice improved (P = 0.001). The\u0000 results revealed that positive attitude led to improved practice of workers in hearing conservation (r = 0.172; P < 0.001), and with increasing knowledge, negative attitude diminished (P=0.014). The results indicated that awareness is correlated with attitude, and attitude could directly\u0000 affect the behavior. Thus, awareness as an intermediate or primary factor might play an important role in developing safe behaviors.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43869845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mariko Tsuruta-Hammaura, G. Wang, Manami Aono, S. Iwamiya
Gender differences in perceived loudness have been observed between Japanese men and women in previous studies. Female participants tended to assign higher loudness scores to sounds of the same sound pressure level than did male participants. However, this difference was not clearly observed when using a ratio scale for the evaluation of loudness, such as in a magnitude estimation. To discuss factors affecting gender differences in perceived loudness, the same rating experiments used in previous studies were conducted with Chinese men and women. A rating experiment using a verbal interval scale showed that Chinese women tended to rate the same sounds as louder than did Chinese men. The gender effect was replicated in an experiment using an adjustment method that measured the limits of the sound pressure level perceived as soft or loud; women selected lower levels than did men for the highest limit of soft sounds and the lowest limit of loud sounds. These tendencies were the same as those of Japanese men and women observed in previous studies. Rating experiments adopting the methods of magnitude estimation and magnitude production for the ratio scales showed that the power exponent a in Stevens' power law was larger for female participants than for male participants under some conditions. However, the observed gender difference in the power exponent a for Chinese was not consistent, while it was not clear for Japanese. The gender difference in criteria for verbally categorizing loudness may be responsible for the gender difference in perceived loudness.
{"title":"Difference in the perceived loudness of sound between Chinese men and women","authors":"Mariko Tsuruta-Hammaura, G. Wang, Manami Aono, S. Iwamiya","doi":"10.3397/1/377022","DOIUrl":"https://doi.org/10.3397/1/377022","url":null,"abstract":"Gender differences in perceived loudness have been observed between Japanese men and women in previous studies. Female participants tended to assign higher loudness scores to sounds of the same sound pressure level than did male participants. However, this difference was not clearly\u0000 observed when using a ratio scale for the evaluation of loudness, such as in a magnitude estimation. To discuss factors affecting gender differences in perceived loudness, the same rating experiments used in previous studies were conducted with Chinese men and women. A rating experiment using\u0000 a verbal interval scale showed that Chinese women tended to rate the same sounds as louder than did Chinese men. The gender effect was replicated in an experiment using an adjustment method that measured the limits of the sound pressure level perceived as soft or loud; women selected lower\u0000 levels than did men for the highest limit of soft sounds and the lowest limit of loud sounds. These tendencies were the same as those of Japanese men and women observed in previous studies. Rating experiments adopting the methods of magnitude estimation and magnitude production for the ratio\u0000 scales showed that the power exponent a in Stevens' power law was larger for female participants than for male participants under some conditions. However, the observed gender difference in the power exponent a for Chinese was not consistent, while it was not clear for Japanese. The gender\u0000 difference in criteria for verbally categorizing loudness may be responsible for the gender difference in perceived loudness.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44428324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A new type of coupled muffler for diesel engine was proposed based on the principle of split-stream rushing and multi-unit coupling theory, and a coupling study of noise attenuation performance was carried out. The one-dimensional transfer matrix method was used to establish a transfer matrix mathematical model of the new muffler. The relative importance of the impact on the transmission loss for the coupled muffler was then able to be ranked by experimental design and MATLAB software calculation. From this, the combination of parameters with the optimal transmission loss was obtained. The transmission loss tests without airflow and the insertion loss tests with airflow between the optimal model of the coupled muffler and the original muffler supplied with the engine were verified respectively. The tests of pressure loss between the coupled muffler and the original muffler were also completed. The results show that the transmission losses of the coupled muffler in 0–2000 Hz and 0–200 Hz without airflow were 6 dB and 8 dB higher than that of the original muffler, the insertion losses of the coupled muffler in 0–2000 Hz and 0–200 Hz with airflow are 6 dB and 7 dB higher than that of the original muffler, and the noise peaks in the source spectrum are well controlled by the coupled muffler. The pressure losses of the coupled muffler are lower than that of the original muffler, which verifies that the coupling structure could reduce the airflow velocity in the muffler to improve noise attenuation performance and aerodynamic performance of the muffler at the same time.
{"title":"Study on the acoustic performance of a coupled muffler for diesel engine","authors":"Jing Xue, Yongan Zhang, He Su, Pei Wu","doi":"10.3397/1/377018","DOIUrl":"https://doi.org/10.3397/1/377018","url":null,"abstract":"A new type of coupled muffler for diesel engine was proposed based on the principle of split-stream rushing and multi-unit coupling theory, and a coupling study of noise attenuation performance was carried out. The one-dimensional transfer matrix method was used to establish a transfer\u0000 matrix mathematical model of the new muffler. The relative importance of the impact on the transmission loss for the coupled muffler was then able to be ranked by experimental design and MATLAB software calculation. From this, the combination of parameters with the optimal transmission loss\u0000 was obtained. The transmission loss tests without airflow and the insertion loss tests with airflow between the optimal model of the coupled muffler and the original muffler supplied with the engine were verified respectively. The tests of pressure loss between the coupled muffler and the\u0000 original muffler were also completed. The results show that the transmission losses of the coupled muffler in 0–2000 Hz and 0–200 Hz without airflow were 6 dB and 8 dB higher than that of the original muffler, the insertion losses of the coupled muffler in 0–2000 Hz and 0–200\u0000 Hz with airflow are 6 dB and 7 dB higher than that of the original muffler, and the noise peaks in the source spectrum are well controlled by the coupled muffler. The pressure losses of the coupled muffler are lower than that of the original muffler, which verifies that the coupling structure\u0000 could reduce the airflow velocity in the muffler to improve noise attenuation performance and aerodynamic performance of the muffler at the same time.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43856441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An important part of evaluating impact sound insulation is to measure the reverberation time in the receiving room. The increasing trend of using wooden structures for residential buildings has made it increasingly important to have control of the measurement procedure at low frequencies. The present ISO standards do not give any specific guidelines for how to deal with frequencies below 50 Hz. It cannot be taken for granted that the present guidelines developed for higher frequencies are also appropriate for lower frequencies. This paper includes an empirical study of the spatial variation of reverberation time, measured from 20 Hz in two different rooms, with about 100 microphone positions in each room. The results from two alternative methods are compared, based upon the impulse response and the interrupted noise respectively. The accuracy of an intended normal measurement procedure is estimated with respect to the number of microphone positions.
{"title":"Uncertainty of in situ low frequency reverberation time measurements from 20 Hz – An empirical study; Part II: Impulse response method","authors":"Fredrik Ljunggren, C. Simmons, M. Pettersson","doi":"10.3397/1/377024","DOIUrl":"https://doi.org/10.3397/1/377024","url":null,"abstract":"An important part of evaluating impact sound insulation is to measure the reverberation time in the receiving room. The increasing trend of using wooden structures for residential buildings has made it increasingly important to have control of the measurement procedure at low frequencies. The present ISO standards do not give any specific guidelines for how to deal with frequencies below 50 Hz. It cannot be taken for granted that the present guidelines developed for higher frequencies are also appropriate for lower frequencies. This paper includes an empirical study of the spatial variation of reverberation time, measured from 20 Hz in two different rooms, with about 100 microphone positions in each room. The results from two alternative methods are compared, based upon the impulse response and the interrupted noise respectively. The accuracy of an intended normal measurement procedure is estimated with respect to the number of microphone positions.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45423860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the prior decades, automotive manufacturers have steadily improved the vibroacoustics performance of their products. This process is highly influenced by the continuously rising requirements on regulations of noise emissions of motor vehicles, also known as pass-by noise. The legal requirements, demanding the reduction of the exterior noise emissions of motor vehicles, are caused by the impact of noise on human health. The latest legal norm of the Economic Commission for Europe (ECE) is the ECE R51.03 test, including continuous reductions of the allowed pass-by noise sound pressure level of motor vehicles. Additionally, the need for faster development cycles results in more intensive use of digital models to predict the expected physical behavior of future products. These models extend the so-called digital twin, which has gained a high importance in automotive manufacturing. Acoustic state-of-the-art simulation and analysis methods fail at the complexity of the over-all pass-by noise, consisting of multiple partial sound sources. These multiple sources are partly correlated, resulting in the absence of trivial deconvolution methods. This paper presents a digital representation of motor vehicles regarding their noise emissions by using machine learning techniques combined with physical calculations of longitudinal driving dynamics. Gradient boosted models are used to predict the exterior sound pressure levels of motor vehicles. The developed algorithm permits the possibility to predict the expected pass-by noise of future cars in early stages of the digital development process. This allows original equipment manufacturers to detect necessary changes to concepts and construction models of future cars. The prediction results are validated for three engines.
{"title":"Pass-by noise prediction of motor vehicles using gradient boosted models and physical calculations of longitudinal driving dynamics","authors":"F. Knappe, J. Rosskopf","doi":"10.3397/1/377019","DOIUrl":"https://doi.org/10.3397/1/377019","url":null,"abstract":"In the prior decades, automotive manufacturers have steadily improved the vibroacoustics performance of their products. This process is highly influenced by the continuously rising requirements on regulations of noise emissions of motor vehicles, also known as pass-by noise. The legal\u0000 requirements, demanding the reduction of the exterior noise emissions of motor vehicles, are caused by the impact of noise on human health. The latest legal norm of the Economic Commission for Europe (ECE) is the ECE R51.03 test, including continuous reductions of the allowed pass-by noise\u0000 sound pressure level of motor vehicles. Additionally, the need for faster development cycles results in more intensive use of digital models to predict the expected physical behavior of future products. These models extend the so-called digital twin, which has gained a high importance in automotive\u0000 manufacturing. Acoustic state-of-the-art simulation and analysis methods fail at the complexity of the over-all pass-by noise, consisting of multiple partial sound sources. These multiple sources are partly correlated, resulting in the absence of trivial deconvolution methods. This paper presents\u0000 a digital representation of motor vehicles regarding their noise emissions by using machine learning techniques combined with physical calculations of longitudinal driving dynamics. Gradient boosted models are used to predict the exterior sound pressure levels of motor vehicles. The developed\u0000 algorithm permits the possibility to predict the expected pass-by noise of future cars in early stages of the digital development process. This allows original equipment manufacturers to detect necessary changes to concepts and construction models of future cars. The prediction results are\u0000 validated for three engines.","PeriodicalId":49748,"journal":{"name":"Noise Control Engineering Journal","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2022-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46077140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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