Acoustics

Accurate predictions of the wave-dominated region of an acoustic field in a room can be generated using wave-based computational methods. One such method is the finite element method (FEM). With presently available computing power and advanced numerical techniques, it is possible to obtain FEM predictions of sound fields in rooms with complicated geometries and complex boundary conditions in realistic time frames. The FEM has been continuously developed since its inception and attempts to provide solutions in real time using finite element-based methods are beginning to appear in the literature; these developments are especially interesting for auralization and virtual acoustics applications. To support these efforts, and provide a resource for neophytes, the use of the FEM for room acoustics is reviewed in this article. A history is presented alongside examples of the method’s derivation, implementation, and solutions. The current challenges and state-of-the-art are also presented, and it is found that the most recent contributions to the field make use of one or a mixture of the following: the finite element-based discontinuous Galerkin method, extended reaction boundary conditions written in the frequency domain but solved in the time domain, and the solution of large-scale models using parallel processing and graphics processing units.

Albert G. Prinn

A Review of Finite Element Methods for Room Acoustics

有限元方法在室内声学中的综述

The transition to alternative electrical energy solutions for drone propulsion systems presents several challenges, particularly in managing noise. This noise, compounded by that from the propellers, can produce spectra that are either unpleasant to humans or detrimental to mission objectives. This study explores potential solutions to mitigate noise produced by a micro turboshaft engine, focusing on the solutions’ impact on weight, power output, and acoustic level. We propose two modular, scalable designs—one for the intake and one for the exhaust—based on well-known applications in cold and hot flows. These designs aim to operate effectively across the audible frequency spectrum and incorporate various Helmholtz resonator geometries, including combinations of different lengths, perforated metal sheet parameters, and cavity-filling materials, to enhance bandwidth and noise reduction. Experimental results indicate that these designs can achieve tonal noise reductions of up to 40 dB. While the results are promising, further analysis is required to evaluate the practical applicability and comprehensive impact of these solutions on drone performance.

Andrei-George Totu

Cristian Olariu

Marius Deaconu

Laurențiu Cristea

Luminița Drăgășanu

Constantin Sandu

Introducing Silencers on Micro Turboshafts Powering Unmanned Aerial Vehicles

在为无人驾驶飞行器提供动力的微型涡轮轴上引入消音器

Kart racing is one of the hobbies that people get passionate about from a young age. Kart dromes are commonly built in suburban or rural areas, generally surrounded by industrial zones and sporadic residential buildings. The circuits are primarily active during summer, hosting races that often extend into the evening and night hours, where each race has a duration of 20 min. This study examines the noise generated by kart dromes through acoustic measurements conducted at a kart drome located in southern Italy, where a microphone was placed at the side of the circuit for short periods in addition to a survey conducted at the nearest sensitive receptor. Another survey was conducted within the kart drome for a long-term period to record all of the variations in noise levels of a typical summer day when the races are organized during the nighttime; for this type of data, the hourly average values were taken for one week in June, July, and August, highlighting the increasing trend in the noise levels due to the kart races. However, a detailed analysis of noise emissions during different phases of kart operation revealed two significant acoustic events, such as the acceleration of pass-by peaks centered on high frequencies and strong breaking noise at curves that are centered at low-medium frequencies, causing a whistling noise of the wheels while turning the kart. This paper highlights the increasing trend in noise levels during summer nighttime races, compares on-site measurements with laboratory data, and discusses the implications for local communities and noise regulations.

Antonella Bevilacqua

Gino Iannace

Luis Gomez-Agustina

Amelia Trematerra

Racing in Kart Dromes: Laboratory and Site Assessment of Noise Levels from Competition and Rental Karts

卡丁车赛道竞速：竞赛与租赁卡丁车噪音水平的实验室与现场评估

The key elements in the operation of modern underwater robotic systems are hydroacoustic communication and navigation systems. Hydroacoustic data transmission channels are designed in such a way that the transmitted information signals must be resistant to various types of interference and distortion, even without preliminary estimates of the channel parameters, due to their significant non-stationarity because of the roughness of the sea surface, currents, and the movement of underwater vehicles. Furthermore, due to the high mobility of underwater vehicles, the transmission time of navigation signals and necessary information packets must be significantly reduced, which can negatively affect the noise immunity of the packages. For these purposes, digital wideband signals and orthogonal frequency division multiplexing (OFDM) are widely used; however, a number of significant drawbacks of these types of modulations often do not allow for the forming of a reliable channel for transmitting information, and for the navigation of mobile underwater systems. Unfortunately, this problem is not comprehensively presented in the literature. The authors propose to use the algorithm of digital data transmission based on the OFDM constant envelope multifrequency modulation (CE-OFDM) with differential symbol coding, which is suitable for non-stationary hydroacoustic environments. The presented algorithm, due to the minimization of the signal peak factor, can improve the signal-to-noise ratio at the receiving end by 5–10 dB, with a number of other advantages, over the classical OFDM method. The authors also numerically found groups of short binary sequences from 14–55 elements long, with the best autocorrelation properties for the formation of synchronization and navigation preambles with high noise immunity to Doppler and multipath effects that are characteristic of the hydroacoustic communication channel. The proposed algorithms were tested on the certain channel models on the Watermark acoustic simulator, as well as in shallow water at distances up to 2 km.

A. Yu. Rodionov

L. G. Statsenko

A. A. Chusov

D. A. Kuzin

M. M. Smirnova

Analysis of the Effectiveness of Multifrequency OFDM Systems with a Constant Envelope in a Hydroacoustic Simulator and During In Situ Tests

水声模拟器和现场测试中恒包络多频正交频分复用系统有效性分析

The aim of this paper is to develop and describe an objective method for measuring the performance of headphones with active noise cancellation (ANC). The focus was on measuring both passive and active sound attenuation and determining the convergence time of the ANC system. A new parameter was introduced—the reaction speed, expressed in dB/ms, allowing an accurate correlation of the active attenuation values with the time needed to achieve them. A series of tests were conducted using three active noise cancelling headphone models of different prices and specifications. The response times were recorded and analyzed. Measurements were performed on two different dummy head models and under two different measurement conditions (reverberation chamber and acoustically adapted room). The results revealed differences between the models, with some headphones consistently providing a better reaction speed. Remarkably, the headphone associated with the lower reaction speed were also the cheapest. This justifies the need for the reaction speed to be a parameter provided by the manufacturer in the datasheet.

Agata Zatorska

Michał Łuczyński

Wojciech Bartnik

Convergence Time Measurement Method of Active Noise Cancelling Headphones

主动降噪耳机收敛时间测量方法

Kunqu Opera, hailed as the “ancestor of all Chinese operas”, plays a crucial role in preserving cultural identity and collective memory in the Jiangnan region. This research examines the acoustical traditions of Kunqu. Through expert interviews and thematic analysis, the study explores key acoustic elements, including vocal techniques and musical structures, and their symbolic and emotional impact. Five central themes emerged, including Kunqu’s role in collective memory, its function as a cultural symbol, the evolution of its transmission, the emotional resonance of its acoustic elements, and the modern challenges and opportunities for preservation. The findings highlight the importance of maintaining Kunqu’s cultural identity within acoustical heritage, while also recognizing the need for innovation in its transmission. This research contributes to the broader discussion on intangible cultural heritage and provides insights into how traditional art forms like Kunqu can be preserved amidst modernization.

Zihan Ding

Francesco Aletta

Acoustical Traditions and Cultural Identity: Exploring Kunqu’s Contribution to Collective Memory

声学传统与文化认同：探索昆曲对集体记忆的贡献

Abbreviation	Acoustics. (Basel).
Journal Impact	1.31
Quartiles(Global)	ACOUSTICS(Q3)

ISSN	2624-599X
h-index	17

Publication Information	Publisher: Multidisciplinary Digital Publishing Institute (MDPI)，Publishing cycle: ，Journal Type: journal，Open Access Journals: Yes
Basic data	Year of publication: 2019，Proportion of original research papers: 100.00%，Self Citation Rate:15.40%， Gold OA Rate: 100.00%
Journal Fees	$Details
Average review cycle	网友分享经验：11 Weeks

Acoustics

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A Review of Finite Element Methods for Room Acoustics

Introducing Silencers on Micro Turboshafts Powering Unmanned Aerial Vehicles

Racing in Kart Dromes: Laboratory and Site Assessment of Noise Levels from Competition and Rental Karts

Analysis of the Effectiveness of Multifrequency OFDM Systems with a Constant Envelope in a Hydroacoustic Simulator and During In Situ Tests

Convergence Time Measurement Method of Active Noise Cancelling Headphones

Racing in Kart Dromes: Laboratory and Site Assessment of Noise Levels from Competition and Rental Karts

Introducing Silencers on Micro Turboshafts Powering Unmanned Aerial Vehicles

Analysis of the Effectiveness of Multifrequency OFDM Systems with a Constant Envelope in a Hydroacoustic Simulator and During In Situ Tests

Acoustical Traditions and Cultural Identity: Exploring Kunqu’s Contribution to Collective Memory

Convergence Time Measurement Method of Active Noise Cancelling Headphones