Acoustical Science and Technology
Online ISSN : 1347-5177
Print ISSN : 1346-3969
ISSN-L : 0369-4232
最新号
—Special Issue on Traffic Noise—
選択された号の論文の25件中1~25を表示しています
PAPERS
  • Yuki Kameyama, Hirona Murakami, Shunsuke Ishimitsu, Keisuke Kotaka, Ya ...
    2025 年46 巻4 号 p. 251-261
    発行日: 2025/07/01
    公開日: 2025/07/01
    [早期公開] 公開日: 2025/04/10
    ジャーナル オープンアクセス

    The widespread use of electric vehicles has altered the perception of automobile sounds in recent years. As automated driving becomes more prevalent, it is assumed that a decrease in cognitive load will make vehicle sounds more noticeable, thereby increasing discomfort while driving. Studies have aimed to reduce the noise disturbance of electric vehicles and evaluate their effects from a physiological perspective. However, no study has examined the attentional mechanisms while driving electric vehicles from a neurophysiological perspective. In this study, we investigated selective attention to vehicle sounds and the effects of changes in vehicle sounds on event-related potentials under driving conditions. Event-related potentials are closely associated with the physical characteristics of stimuli, the cognitive processes of perception, and selective attention. We examined event-related potentials, such as P3, during driving to understand their relationship with selective attention in the driving environment. Our study revealed differences in event-related potentials with subtle changes in vehicle sound pressure levels while driving. Furthermore, we found that differences in attentional engagement may be evoked by sound pressure level changes. These results will help investigate practical approaches to reduce vehicle noise and enhance comfort within car interiors.

  • Tianhan Tang, Ichiro Sakuma, Takashi Azuma, Shin-Ichiro Umemura, Atsus ...
    2025 年46 巻4 号 p. 262-273
    発行日: 2025/07/01
    公開日: 2025/07/01
    [早期公開] 公開日: 2025/02/21
    ジャーナル オープンアクセス

    Ultrasound Computed Tomography is increasingly valued for breast cancer diagnosis. However, traditional echo imaging method, particularly the synthetic aperture method, though high in resolution, requires extensive data acquisition from numerous transducer element combinations. This leads to prolonged data collection, substantial storage and transfer burdens, and ultimately reduced throughput, limiting ultrasound computed tomography's practicality. This study introduces a minimal data-acquisition strategy for echo imaging, leveraging a pixel-based imaging method. Our method aims to find an optimal transducer elements configuration that meets two criteria: minimizing the number of elements and ensuring the associated measurement matrix has a sufficiently small condition number to remain robust against random noise. By using this approach, we can significantly reduce the amount of data required for image reconstruction without compromising image quality compared to the synthetic aperture method. Through simulation studies, we demonstrate that our method requires only 1/8th the number of elements and 1/64th the amount of data used by the synthetic aperture method while reconstructing images with comparable resolution and enhanced contrast. This advancement is valuable in boosting screening throughput, lowering system costs, and potentially improving diagnostic accuracy, marking a significant step forward in ultrasound computed tomography technology for breast cancer detection.

  • Shumpei Yamamoto, Masamitsu Sannomiya, Yoshinori Takahashi
    2025 年46 巻4 号 p. 274-285
    発行日: 2025/07/01
    公開日: 2025/07/01
    [早期公開] 公開日: 2025/03/13
    ジャーナル オープンアクセス

    This paper aims to establish a method for preserving three-dimensional shape data of valuable wind instruments such as those housed in museums as cultural assets, as well as for creating replicas having the same playing feel and timbre as original instruments. In this paper, a three-dimensional computer model of a classical oboe made around 1800 was built through X-ray CT scanning, and physical copies of the instrument (replicas) were fabricated using an additive manufacturing. The replicas were then evaluated by analyzing the harmonic structure of the played sound and by listening experiments to see whether the timbres of the replicas could be distinguished from that of the original instrument. Despite the fact that the replicas were made of different materials from the original instrument, it was found that they had only slightly different harmonic structures from the original's and that the subjects in the listening experiments had difficulty in distinguishing the timbres.

  • Yotaro Kurai, Satoshi Sekimoto, Yuki Ueda
    2025 年46 巻4 号 p. 286-294
    発行日: 2025/07/01
    公開日: 2025/07/01
    [早期公開] 公開日: 2025/02/21
    ジャーナル オープンアクセス

    Thermoacoustic refrigerators offer the advantages such as being environmentally friendly due to the usage of common gases such as helium, argon, and nitrogen gases as their working fluids. This paper presents a nonlinear model of a traveling-wave thermoacoustic refrigerator capable of accurate analysis at large amplitudes, which enables the performance prediction and design of high-power thermoacoustic refrigerators. To develop the model, the loudspeaker parameters were measured and modeled. In addition, the acoustic power losses that occurred when sound waves passed through the bend and T-junction tubes were measured. Based on these experimental results, the thermoacoustic refrigerator model was proposed and verified under large-amplitude conditions.

  • Kuan-Yu Chen, Yu-Chih Tzeng, You-Sheng Yeh
    2025 年46 巻4 号 p. 295-302
    発行日: 2025/07/01
    公開日: 2025/07/01
    [早期公開] 公開日: 2025/04/03
    ジャーナル オープンアクセス

    This study adopts the Taguchi method to determine the optimal robust parametric levels for enhancing the sound absorption performance of 316L stainless steel foam. The factors examined in this study are the average pore size (1.1–4.4 mm), the porosity (48–61%), and the thickness (10–30 mm). Each factorial contribution is evaluated using an analysis of variance (ANOVA). The analysis indicates that porosity is the most significant factor, accounting for 89.4% of the total variance, while pore size and thickness have a smaller influence. There is no interaction between the factors. An increase in the porosity increases the sound absorption coefficient. The optimal combination of factor levels for sound absorption specifies a pore size of 1.1 mm, a porosity of 61%, and a thickness of 30 mm. The highest sound absorption coefficient of 0.7 is attained at a frequency of 6,300 Hz. This study proposes a useful approach combining the Taguchi method with ANOVA designed to accelerate the development of the sound adsorption performance of metal foam.

  • Hikaru Yanagida, Yusuke Ijima, Naohiro Tawara
    2025 年46 巻4 号 p. 303-314
    発行日: 2025/07/01
    公開日: 2025/07/01
    [早期公開] 公開日: 2025/03/14
    ジャーナル オープンアクセス

    Previous studies have shown that speech spoken by someone familiar is more intelligible than an unfamiliar voice in the presence of a competing talker. Although the voices of friends or family members were the familiar voices in these previous studies, other studies have shown that one's own recorded voice is more familiar than others' voices. However, the intelligibility of one's own recorded voice still remains unclear. The aim of this study is to investigate the intelligibility of one's own recorded voice compared with the voices of others. We conducted a large-scale online Japanese version of the coordinate-response-measure (CRM) task including one's own and others' recorded voices with 137 Japanese participants. The results showed that one's own recorded voice is more intelligible than others' voices when there is a competing talker. We also analyzed the relationship between the performance of the CRM task and impressions of one's own recorded voice. The results indicated that the intelligibility benefit of one's own recorded voice was significantly greater for participants who rated their own recorded voice higher in terms of similarity or intelligibility compared with those who rated it lower.

  • Yusuke Makino, Yasushi Takano, Makoto Otani, Mariko Akutsu, Toki Uda
    2025 年46 巻4 号 p. 315-325
    発行日: 2025/07/01
    公開日: 2025/07/01
    [早期公開] 公開日: 2025/04/11
    ジャーナル オープンアクセス

    Amplitude modulations of an aerodynamic sound by sound source movement or convection is investigated experimentally. The directivities of an aeolian tone sound radiated from a cylinder fixed in a wind tunnel were measured with horizontally aligned microphones outside the flow as a simplified dipole component of aerodynamic sound generated by pressure fluctuations, which is dominant at low Mach number. The results show that the acoustic intensity of radiated sound can increase approximately in inverse proportion to the fourth power of the ratio of the apparent wavelength of the radiate sound to the original wavelength. The amplitude modulation of the sound by convection was measured and then compared with the modulation of the same sound by source movement. The result revealed that an aerodynamic sound leads to a larger amplitude modulation by source movement compared with the modulation measured in a wind tunnel experiment, although the apparent wavelength of sound radiated from the same source in the atmosphere changes by the same proportion.

  • Kazuki Matsumoto, Kohei Yatabe
    2025 年46 巻4 号 p. 326-337
    発行日: 2025/07/01
    公開日: 2025/07/01
    [早期公開] 公開日: 2025/04/08
    ジャーナル オープンアクセス

    Solving the permutation problem is essential for determined blind source separation (BSS). Existing methods, such as independent vector analysis (IVA) and independent low-rank matrix analysis (ILRMA), tackle the permutation problem by modeling the co-occurrence of the frequency components of source signals. One of the remaining challenges in these methods is the block permutation problem, which may cause severe performance degradation. In this paper, we propose a simple and effective technique for solving the block permutation problem. The proposed technique splits the entire frequency bands into several overlapping subbands and sequentially applies BSS methods (e.g., IVA, ILRMA, or any other method) to each subband. Since the splitting reduces the size of the problem, the BSS methods can effectively work in each subband. Then, the permutations among the subbands are aligned by using the separation result in one subband as the initial values for the other subbands. Additionally, we propose SS-IVA and SS-ILRMA by combining subband splitting (SS) with IVA and ILRMA. Experimental results demonstrated that our technique remarkably improves the separation performance without increasing computational cost. In particular, our SS-ILRMA achieved the separation performance comparable to the oracle method (frequency-domain independent component analysis with the ideal permutation solver). Moreover, SS-ILRMA converged faster than conventional IVA and ILRMA.

TECHNICAL REPORT
  • Jing Sun, Tatsuya Kitamura, Ryoko Hayashi
    2025 年46 巻4 号 p. 338-344
    発行日: 2025/07/01
    公開日: 2025/07/01
    [早期公開] 公開日: 2025/02/15
    ジャーナル オープンアクセス

    The analysis of articulatory movements, particularly tongue movements, is a key challenge in speech research. However, traditional methods for extracting tongue contours often face difficulties due to poor image quality and noise interference, complicating tongue motion analysis. This study proposes a novel approach to automatically extract the contours of the tongue and other articulatory organs from ultrasound and real-time magnetic resonance imaging (rtMRI) data. We employed DeepLabCut (DLC), a deep-learning-based tool. Our experiments demonstrated that DLC is not reliant on image edges or contrast, demonstrating robustness against noise and enabling effective automatic contour extraction. This paper highlights the method used and evaluates the accuracy of contour extraction for the tongue and other articulatory organs. By leveraging advanced deep-learning techniques, we aim to enhance the understanding of articulatory movements and improve speech analysis tools, ultimately contributing to enhanced outcomes in speech therapy and pronunciation training.

ACOUSTICAL LETTERS
—Special Issue on Traffic Noise—
INVITED REVIEW
PAPERS
  • Nguyen Thanh Tung, Yasunao Matsumoto, Shigenori Yokoshima, Takashi Mor ...
    2025 年46 巻4 号 p. 430-441
    発行日: 2025/07/01
    公開日: 2025/07/01
    [早期公開] 公開日: 2024/09/20
    ジャーナル オープンアクセス

    There have been only a limited number of studies in which the subjective responses to traffic-induced vibration and noise in buildings are experimentally compared among participants from different nations. In this study, we investigate the subjective responses of two groups to vibration and noise: one group comprises 20 Vietnamese participants and the other 20 Japanese participants. The participants were exposed to noises of six different levels and vibrations of five varying magnitudes, which were obtained from field measurement recordings of road traffic, Shinkansen railways, and conventional railways. They were asked to rate their levels of discomfort and reading disturbance on a seven–ordinal scale and a five–ordinal scale, respectively. The results indicate that the Japanese participants rated significantly greater discomfort levels in response to noises of most levels and vibrations of certain magnitudes, than the Vietnamese participants. The difference in reading disturbance level between the two groups was less clear than that in discomfort level. The subjective equivalences between vibration and noise did not differ significantly between the Japanese and Vietnamese groups.

  • Tsumugi Nakayama, Shunsuke Kouda, Takatoshi Yokota
    2025 年46 巻4 号 p. 442-452
    発行日: 2025/07/01
    公開日: 2025/07/01
    [早期公開] 公開日: 2024/12/10
    ジャーナル オープンアクセス

    We developed a method for determining the inclusion of disturbance sounds in aircraft noise events using a convolutional neural network (CNN). Considering road-traffic noise as a disturbance sound, recognition models were developed for aircraft and road-traffic noise (hereafter referred to as the base model) and then combined. In addition, we developed a new model, the "frequency-split parallel model," by advancing the base model. This approach involved inputting spectrograms split along the frequency axis. After verifying the accuracy of each model for single sound events of aircraft and road-traffic noises, the frequency-split parallel model was evaluated using superimposed data obtained around Narita International Airport and compared with the base model. The misidentification rate of road-traffic noise as aircraft noise decreased by approximately 57% compared to the base model, and 16 out of 17 measured superimposed events were correctly determined. These results confirm the effectiveness of the proposed method.

  • Mariko Akutsu, Toki Uda, Yasuhiro Oikawa
    2025 年46 巻4 号 p. 453-462
    発行日: 2025/07/01
    公開日: 2025/07/01
    [早期公開] 公開日: 2024/12/11
    ジャーナル オープンアクセス

    Sound wave propagation from a moving sound source, such as the Shinkansen, is affected not only by the source movement but also by the airflow around the source. Previous theoretical studies showed that variations in sound wave propagation depend on the airflow distribution. However, few experimental studies have been conducted, because the experimental study of the sound propagation from a moving sound source requires the installation of microphones, which inevitably affect the airflow. Thus, the actual effect of airflow remains unclear. In this study, we experimentally investigate the effect of airflow around a moving sound source using a parallel phase-shifting interferometer, which is a noncontact optical sound measurement method. We conducted wind tunnel tests with a scaled train model, which includes a sound source to visualize sound wave affected by a boundary layer. Additionally, we conducted moving-model tests to investigate the sound propagation around the moving scaled train model. The results show that the sound wave propagation characteristics change, and several phenomena, such as wavefront distortion, sound trapped in the boundary layer, and shadow zone formation, occur. Additionally, sound wavelength modulation and sound frequency modulation were observed in the wind tunnel and moving-model tests, respectively.

  • Xinyi Zhang, Shinichi Sakamoto
    2025 年46 巻4 号 p. 463-469
    発行日: 2025/07/01
    公開日: 2025/07/01
    [早期公開] 公開日: 2025/01/31
    ジャーナル オープンアクセス

    Road traffic noise is one of the most widespread environmental noise sources, significantly impacting public health. To control traffic noise pollution, the European Union requires countries to prepare strategic road traffic noise maps using prediction models every five years since 2007. Similarly, Japan has developed its own road traffic noise maps based on regular on-site observations. However, traditional methods of collecting traffic data through on-site measurements are labor-intensive and costly. Therefore, in this work, we present a method for creating road traffic noise maps using an object detection deep learning algorithm to extract road traffic conditions, such as vehicle types and speeds, from aerial photographs. On the basis of ASJ RTN-Model 2018, the traffic condition data serves as the foundation for calculating the sound power levels of road traffic noise for different roads. The road traffic noise map is then created directly from the sound pressure level distribution within the considered regions. We validated the accuracy of the detection model and the calculated sound pressure level along the road from the aerial photographs against the published measurements. Using the proposed method, we created the road traffic noise map for Meguro City, Tokyo.

  • Yusuke Makino, Yasushi Takano, Makoto Otani, Mariko Akutsu, Toki Uda
    2025 年46 巻4 号 p. 470-479
    発行日: 2025/07/01
    公開日: 2025/07/01
    [早期公開] 公開日: 2024/10/05
    ジャーナル オープンアクセス

    Both amplitude modulation and frequency modulation occur in a sound field radiated from moving sound sources. However, the amplitude modulation for different source types has not been clarified experimentally. In this study, the directivities of sound radiated from an ultrasonic transducer attached to a moving scaled train model and used as a simplified vibrational sound source were measured. The surface of the vibrational source was parallel to the movement direction of the source. The directivities of an aeolian tone sound generated using a cylinder attached to the train model were also measured; the cylinder was used as an aerodynamic sound source for a simplified dipole component of aerodynamic sound, which is dominant at low Mach numbers, generated from pressure fluctuation. The experimental results show that the acoustic intensity of sound radiated from a vibrational source increases roughly in proportion to the fourth power of the Doppler factor, whereas that of the dipole component of aerodynamic sound increases roughly in proportion to the eighth power of the Doppler factor. Sound radiated from an aerodynamic source moving at low Mach numbers leads to a greater amplitude modulation due to source movement compared with sound radiated from a vibrational source.

TECHNICAL REPORTS
  • Junta Tagusari
    2025 年46 巻4 号 p. 480-485
    発行日: 2025/07/01
    公開日: 2025/07/01
    [早期公開] 公開日: 2024/06/01
    ジャーナル オープンアクセス

    Areas in the vicinity of trunk roads are exposed to high levels of noise and may pose high health risks to residents. To assess the health risks and formulate effective noise mitigation measures, prediction of road traffic noise is crucial. Addressing this issue, the author has developed a road traffic noise prediction system that allows prediction of sound levels using a database of road network. The objective of the present study was to predict road traffic noise in the vicinity of the trunk roads using a Digital Road Map Platform (DRM-PF) database, which contains nationwide road geometries and traffic settings of trunk roads. Predicted sound levels were compared with actual measurements and noise maps were created to demonstrate the feasibility of assessing noise exposure and associated health risks in the vicinity of trunk roads in Japan. The results show a generally good agreement between predicted and measured levels, while challenges remain in accurate prediction in a number of environments, mainly due to the lack of accurate geometries. The extensive coverage of the DRM-PF database throughout Japan enables noise mapping in arbitrary regions near trunk roads, which would contribute to making noise policy.

  • Shinichi Sakamoto
    2025 年46 巻4 号 p. 486-493
    発行日: 2025/07/01
    公開日: 2025/07/01
    [早期公開] 公開日: 2024/11/30
    ジャーナル オープンアクセス

    In ASJ RTN-Model 2018, a practical calculation method of the ground effect in A-weighted overall level for road traffic noise is specified by relatively simple formulae. The method is derived from the solution of wave propagation on an infinite and flat ground with acoustic impedance based on wave theory. By the practical calculation method, the attenuation level by the ground effect for a relatively long distance between the source and receivers tends to become larger on softer ground. Especially in the cases of lower sound source positions as specified in the ASJ RTN-Model 2018, the excess attenuation becomes considerably large. To investigate the appropriate treatment of the ground condition in the case of road traffic noise propagation on soft ground, the authors have performed an on-site measurement of road traffic noise. The measurement results were compared with calculation results by both the ASJ RTN-Model 2018 and the theoretical solution based on the wave theory. From the comparison, the features of the propagation characteristics obtained by the ASJ RTN-Model 2018 were discussed.

  • Katsuya Yamauchi
    2025 年46 巻4 号 p. 494-500
    発行日: 2025/07/01
    公開日: 2025/07/01
    [早期公開] 公開日: 2024/10/25
    ジャーナル オープンアクセス

    To evaluate the exterior noise reduction effects of electric vehicles (EVs) and hybrid electric vehicles (HEVs) under non-steady speed conditions, i.e., accelerating or decelerating running conditions, measurements of A-weighted sound power levels were conducted. This paper reports the results of a reanalysis using the data measured at the same test site. The results are shown as regression models of the sound power level depending on the vehicle speed. For internal combustion engine vehicles (ICEVs), there was a strong tendency for LWA to increase when the acceleration was greater than 1.0 m/s2. For EVs, when the acceleration is less than 2.0 m/s2, which is considered the typical acceleration in general urban driving, it can be considered equivalent to the LWA under steady-speed condition. During deceleration, there was no significant difference from steady-speed condition for either vehicle type. These differences were examined in terms of single-event sound exposure levels. In a case study that included stopping and going at a traffic signal, the difference in LEA was shown to be 3.0 dB.

ACOUSTICAL LETTER
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