Acoustic Research Research Articles

3D-printed acoustic head simulators that talk and move

Acoustic head simulators are used to collect realistic binaural audio with accurate interaural cues. Head simulators are difficult to acquire and often provide only listening and recording capabilities. For cocktail parties and conversation scenarios, it is necessary to have many head simulators that can simultaneously produce speech and capture sound. An added dimension of realism can be provided with motion. We rely on 3D printing to fabricate a large number of head simulators, each of which is equipped with a loudspeaker for mimicking speech production. We use silent multi-axis turrets to provide neck-like motion. Our actuated head simulator collection is integrated into the Mechatronic Acoustic Research System.

Assessment of Middle Ear Function Using Wideband Acoustic Immittance: Current Practices and Future Prospects.

Acoustic immittance tests have been used in clinical practice for the assessment of middle ear function since the 1960s. In the following decades, single-frequency admittance tympanometry has become a staple test of middle ear function in routine audiological practice, and to a lesser extent, multifrequency tympanometry. The acoustic properties of middle ear are best understood through physiological assays of its gain spectrum, tested over a wide range of frequencies; i.e., the middle ear transfer function. Yet, clinical assessment with multi-frequency tympanometry has been limited to frequencies below 2000 Hz. Thanks to advances in probe characterization techniques, measurements of impedance at frequencies beyond 2,000 Hz have become possible. These advances ushered in a new frontier for acoustic immittance research and paved the way for a host of new wideband acoustic immittance (WAI) measures that promised improved clinical assessments through better approximation of the transfer function and acoustic mechanics of the middle ear. Translational and clinical research further developed and refined WAI for clinical use through establishment of clinical norms, emergence of data in ears with conductive disorders, and demonstrated improvements in test accuracy of WAI over single-frequency tympanometry for a variety of clinical populations. Together with emergence of commercially available systems, since the mid-2000s, these developments signal the emergence of WAI testing as a standard audiological tool for the assessment of the middle-ear function. Although clinical adoption of this promising diagnostic technology is lagging, widespread adoption is expected with further refinement of WAI measures, and as updated clinical practice guidelines recommend the incorporation of WAI testing into clinical test batteries (e.g., JCIH, 2019).[1]

Hybrid space filling curve metamaterials for transmissive flow in Jet Engine inlets

Acoustic metamaterials research has grown exponentially in the past 10 years driven by the advances in manufacturing and an increased understanding of damaging environment noise. 2050 was the first noise reduction target as set by Advisory Council for Aircraft Research and Innovation in Europe with a relative 65% decrease. This ambitions target will not be met by current engine noise control technology; however, metamaterials offer an encouraging alternative. Space Filling Curves (SFC) have the potential to provide a lightweight, thin, high performance acoustic liner. SFC have a history in mathematical geometry dating back to the 1890's but are a comparatively new addition to acoustics. They are designed with a sub-wavelength curled cross-section creating a maze-like pattern which slows acoustic wave propagation through the liner, enabling characteristics such as negative refraction and low frequency attenuation. This paper contains unique hybrid designs combining some of the most promising SFC metamaterial acoustic liner designs, in terms of the fundamental theory of the design category and a discussion of the reflection, absorption and transmission characteristics in terms of a grazing flow conditions. Experimental impedance tube testing compares 3D printed designs to the traditional Helmholtz resonator. The paper concludes with future application for aeroacoustics with particular focus on the engine inlet.

Flow current field observation with underwater moving acoustic tomography

Underwater environment observation with underwater acoustic tomography has been considerably developed in recent years. Moving sound transmission can obtain the observation of entire spatial area with sound station moving. Various internal structures, unique surface and submarine boundaries and changing environment constitutes a complex acoustic propagation channel. This paper focus on the inversion method and signal resampling for sound moving transmission. Also, the current field in three-dimensional (3D) scale is also studied. A five-station sound transmission experiment with four moored station and one moving station that conducted in range of 500m×500m at Huangcai reservoir, Changsha, China is presented. Signal resampling is performed to get correlation of received acoustic data. The vertical layer-averaged flow current results between moving station and moored station are inversed with 2D grid method. 3D flow current field result is composed by grid-averaged inversion current of vertical profile via moving station at different moment. The received results of reciprocal signal transmission between two moored stations and one moving station were used for layer-averaged current variations at vertical scale and grid-averaged current. The feasibility of the method in underwater moving acoustic tomography research is proved and its applicability is discussed. The proposed underwater acoustic tomography technology develops an innovative idea for the further development of temporal- spatial grided tomography observation.

A glimpse at fifty-one years in acoustic emission

After 51 years continuously involved in acoustic emission (AE) testing and research, it has been interesting to look back over five decades. The equipment available in the early 1970s was primitive compared to now. At the start of that decade, only one, recently established, commercial company sold AE measurement equipment, and other useful equipment was internally built or adapted from other technologies. Further, the data that came from an AE monitored test was simply the number (counts) of penetrations of a fixed one-volt threshold expressed as an increasing total or a rate and recorded on an x-y plotter. The purpose of this “glimpse” is to present advances both within the author’s research as well as those that were adopted from others research that were viewed as moving AE technology forward. This “glimpse” is not intended to be comprehensive, instead it is limited to aspects the author was involved in. Among the topics to be covered are advances such as understanding hydraulic test machine continuous noise, true rootmean-square (RMS) voltage measurements, inclusion particle fracture or decohesion, tension versus compression testing for unflawed metal samples, the pencil lead break, an acoustic emission signal simulator, broadband sensors, digital waveform recorders, large transversedimensioned plates, absolutely calibrated flat-with-frequency AE sensors, finite element modeling (FEM) in isotropic materials, validation of FEM, computer-based digital AE systems, intensity of frequency versus time of AE signals, superposition of group velocity results and FEM beyond the case of dipoles in an isotropic plate.

PMEL Passive Acoustics Research: Quantifying the Ocean Soundscape from Whales to Wave Energy

Passive acoustic monitoring of the global ocean has increased dramatically over the last decade, providing insights into seasonal sea ice and wind/wave variability, biodiversity, geophysical hazards, and anthropogenic noise impacts. All of these phenomena are sentinels of marine ecosystem health and ocean climate change. Recognizing the utility of underwater sound, the Pacific Marine Environmental Laboratory (PMEL) formed a passive acoustic research program with the goal of quantifying deep-ocean and coastal soundscapes in support of NOAA’s mission to conserve and manage marine ecosystems. PMEL Acoustics Program researchers have built a stable of novel ocean technologies, including autonomous stationary hydrophones, mobile platforms, and near-real-time surface buoys with satellite communication capability. These passive acoustic monitoring systems have been deployed in every major ocean basin on Earth, enabling significant advancements in understanding of natural and anthropogenic sounds. This progress includes evaluation of human-made sound levels across US waters, observations of ship noise fluctuations during the COVID-19 pandemic, and evaluation of noise levels from offshore wave-energy devices. Our natural sound research includes assessment of seasonal variability in the presence of endangered cetacean species due to population recovery and/or changing ocean temperatures as well as early detection of the collapse of an Antarctic ice shelf.

Acoustic research for telecoms: bridging the heritage to the future

In its early age, telecommunication was focused on voice communications, and acoustics was at the heart of the work related to speech coding and transmission, automatic speech recognition or speech synthesis, aiming at offering better quality (Quality of Experience or QoE) and enhanced services to users. As technology has evolved, the research themes have diversified, but acoustics remains essential. This paper gives an overview of the evolution of acoustic research for telecommunication. Communication was initially (and for a long time) only audio with a monophonic narrow-band sound (i.e. [300–3400 Hz]). After the bandwidth extension (from the wide-band [100–7000 Hz] to the full-band [20 Hz–20 kHz] range), a new break was the introduction of 3D sound, either to provide telepresence in audioconferencing or videoconferencing, or to enhance the QoE of contents such as radio, television, VOD, or video games. Loudspeaker or microphone arrays have been deployed to implement “Holophonic” or “Ambisonic” systems. The interaction between spatialized sounds and 3D images was also investigated. At the end of the 2000s, smartphones invaded our lives. Binaural sound was immediately acknowledged as the most suitable technology for reproducing 3D audio on smartphones. However, to achieve a satisfactory QoE, binaural filters need to be customized in relation with the listener’s morphology. This question is the main obstacle to a mass-market distribution of binaural sound, and its solving has prompted a large amount of work. In parallel with the development of technologies, their perceptual evaluation was an equally important area of research. In addition to conventional methods, innovative approaches have been explored for the assessment of sound spatialization, such as physiological measurement, neuroscience tools or Virtual Reality (VR). The latest development is the use of acoustics as a universal sensor for the Internet of Things (IoT) and connected environments. Microphones can be deployed, preferably with parcimony, in order to monitor surrounding sounds, with the goal of detecting information or events thanks to models of automatic sound recognition based on neural networks. Applications range from security and personal assistance to acoustic measurement of biodiversity. As for the control of environments or objects, voice commands have become widespread in recent years thanks to the tremendous progress made in speech recognition, but an even more intuitive mode based on direct control by the mind is proposed by Brain Computer Interfaces (BCIs), which rely on sensory stimulation using different modalities, among which the auditory one offers some advantages.

Localization of car engine noise sources

The engine of a vehicle, particularly a passenger car, is one of the main sources of noise radiated into the environment and creates a noise load in residential areas, which has a negative impact on people. Experts in the field of acoustics perform computational and experimental acoustic studies both at the design stage, and at the stage of putting into production and directly operating the engine as part of the car to reduce engine noise. An important stage of acoustic research is the localization of the most intensely radiating noise of systems, mechanisms, nodes and engine parts. The article presents the results of experimental studies on localization of internal combustion engine noise sources of a LADA car.

Improvement of Classical Music Sound Conditions by Simulating Changes in Concert Hall Acoustics

The purpose of the research is to propose a method of acoustic research of concert halls to improve the classical music sound conditions with the help of innovative computer technologies. The research methodology is as follows: to improve the sound conditions of classical music, a computer simulation method is proposed, which involves the use of specialized software. The method of subjective evaluation through the criteria of the established sample is used to systematize the results of the study. The comparative method was used to analyze the sound of audio materials of the created spatial sound images of the orchestral music sample. The scientific novelty of the research is that it presents a methodology of acoustic research for the environment, in particular concert halls, which arose as a result of changes in the acoustic conditions of classical music. Conclusions. As a result of the experiment, the main goal was achieved – to improve the sound conditions of classical music. The result was achieved by modeling changes in the acoustics of the concert hall. The use of this methodology can be recommended during the research of existing and projected concert halls. In further studies, the use of diffusers with low absorption coefficients in the lower frequency band can be recommended. It should also be noted that interference with the interior of a historic building should be discreet, as this may cause dissatisfaction among the authorities controlling heritage preservation.

A review on acoustic vortices: Generation, characterization, applications and perspectives

Acoustic vortices provide a single-beam approach to manipulate objects with sizes from nanometers to millimeters, gaining increasing interest in recent years. The helical beam renders them good ability to trap particles in three dimensions stably. At the same time, the orbital angular momentum of acoustic vortices can be used to realize object rotation and data transmission. In this review, we summarize the generation and characterization of acoustic vortices. Furthermore, we present the application of acoustic vortices in particle manipulation, object rotation, acoustic communication, and especially in the biomedical field. Finally, perspectives on the future directions for acoustic vortex research are discussed.

Review and prospects of metamaterials used to control elastic waves and vibrations

Acoustic metamaterials, artificial composite structures with exotic material properties used to control elastic waves, have become a new frontier in physics, materials science, engineering and chemistry. In this paper, the research progress and development prospect of acoustic metamaterials are reviewed. Related studies on passive acoustic metamaterials and active acoustic metamaterials are introduced and compared. Additionally, we discuss approaches to material structure design, including topology optimization approaches, as well as bio-inspired and fractal geometry-based approaches to structure design. Finally, we summarize and look forward to the prospects and directions of acoustic metamaterial research. With the development of additive manufacturing technology, the research potential of acoustic metamaterials is huge.

Research on the Acoustic Environment of Heritage Buildings: A Systematic Review

As a significant part of heritage building protection, an increasing number of researchers pay attention to the study of the acoustic environment. The purpose of this study was to provide a clear understanding of the status quo of acoustic environment research on heritage buildings and discuss future development directions through a systematic literature review. The PRISMA protocol was used to conduct a systematic evaluation based on 42 studies on the acoustic environment of heritage buildings retrieved from databases such as the Web of Science. Research on the acoustic environment of heritage buildings mainly focused on the following four aspects: the acoustic environment with different functions, the influence of building materials on the acoustic environment, the digitization of acoustic heritage, soundscape measurement, and perception of the historical area. Second, this study discusses the development trend of acoustic environment research of heritage buildings and the shortcomings of current research. Finally, this study provides a comprehensive overview of the acoustic environment research of heritage buildings and offers suggestions for future research.

DEVELOPMENT OF A DEVICE AND SOFTWARE COMPLEX FOR ACOUSTIC DIAGNOSTICS OF PROCESSES OCCURRING IN THE SUPERCRITICAL STATE OF A LIQUID AND MONITORING THE WORK OF A MAGNETIC DRIVE UNIT

There is a problem of studying the processes that occur during the transition of a liquid to a supercritical state and in the process of studying and conducting experiments. There is also a problem of controlling the operation of the electromagnetic device system. Since mechanical, electronic, and other control methods are complicated by the conditions (extremely high pressure, high temperature, location of a part that needs control inside a sealed metal system and is under radiation), an acoustic research method was chosen. As a result of the development, a device based on STM32F407VGT6, DP83848, MAX9814 was created that allows you to receive acoustic data and transmit them over considerable distances using an Ethernet network. Also, applications were developed that enable visualization, storage and processing of acoustic data: a TCP server for data exchange, an operator application that helps to visually control the operation of the magnetic drive and save acoustic data in CSV format, an application for visualization and processing of stored data using methods of statistical and spectral analysis.

Effect of torso reflections from simplified torso models on head-related transfer function simulation and ipsilateral perception of elevation

The effect of torso reflection on head-related transfer functions (HRTFs) is considered a suitable elevation localization cue for lateral sound sources below 3.0 kHz, and various torso models have been hitherto adopted in HRTF simulation. However, their torso reflection effects have not been compared in detail. This work analyzes the torso reflection effects of the representative torso models on HRTFs, and further evaluates their elevation localization performance via psychoacoustic experiments. The results show that the semi-ellipsoidal torso and truncated Knowles Electronics Mannequin for Acoustic Research (KEMAR) torso, both of which have considerable advantages over the spherical torso, can achieve better elevation localization performance, which validates the torso with human-like shape provide enough torso reflection and have a better ability in low-frequency lateral elevation perception.

Acoustics Research Progress on Characteristics of Jellyfish Aggregation

Jellyfish blooming threatens the safety of coastal industrial and personal safety. In recent years, ocean eutrophication, ocean engineering, global warming and other factors have combined to create a more serious situation. Traditional studies on the ecological behavior characteristics of jellyfish mainly rely on the methods of net fishing and visual observation. The use of acoustic technology for the acoustic monitoring of jellyfish has been applied in Europe, the United States, Japan, South Korea and other countries, showing good observation effect and application potential in the study of resource assessment and kinematic law.

Acoustic researches of arctic cod <i>Boreogadus saida</i> (Gadidae) in the southwestern Chukchi Sea in 2003–2020

Spatial distribution patterns and abundance of arctic cod Boreogadus saida are considered for the southwestern Chukchi Sea on the data of acoustic surveys and trawl samples obtained by TINRO research vessels in 2003–2020. The highest abundance and biomass of this species indicated by the echosounder–measured backscattering coefficient sA (m2 per sq.n.mile) were observed in August 2003, decreased significantly in 2007–2008 and later, with the minimum in 2010, increased in 2014 due to the high portion of juveniles, but continued to decrease in recent years and reached the lowest value in 2020. This negative tendency for arctic cod contradicts to the walleye pollock abundance increasing in the southwestern Chukchi Sea on the background of warming in the Arctic. The arctic cod were distributed mainly in the northeastern and southwestern parts of the surveyed area, usually as vast fields of small schools or sparse layers. To the east from 174°W, the aggregations were formed by large-sized fish distributed mostly at the bottom. In the western area, the aggregations were formed within thermocline at the depth of 10–20 m or had two–layer structure with the juveniles dominated in the upper layer and larger fish at the bottom. Typical echograms showed dense schools of arctic cod with the height up to 30 m and horizontal size of 120–400 m, presumably formed by migrating fish. Diurnal vertical migrations were not expressed for this species, though the aggregations of lower density were observed at night, in general, with some local aggregations of permanently dense schools, both in the daytime and at night.

Graduate education and research in architectural acoustics at Rensselaer Polytechnic Institute

The Graduate Program in Architectural Acoustics has been constantly advanced from its inception in 1998 with an ambitious mission of educating future experts and leaders in architectural acoustics, due to the rapid pace of change in the fields of architectural-, physical-, and psycho-acoustics, and noise-control engineering. Since years the program’s pedagogy using “STEM” (science, technology, engineering, and mathematics) methods has been proven to be effective and productive, including intensive, integrative hands-on experimental components that integrate architectural acoustics theory and practice. The graduate program has recruited graduate students from a variety of disciplines including individuals with B.S., B.Arch., or B.A. degrees in Mathematics, Physics, Engineering, Architecture, Electronic Media, Sound Recording, Music and related fields. Graduate students under this pedagogy and research environment have been succeed in the rapidly changing field. RPI’s Graduate Program in Architectural Acoustics has since graduated more than 120 graduates with both M.S. and Ph.D. degrees. Under the guidance of the faculty members they have also actively contributed to the program’s research in architectural acoustics, communication acoustics, psycho-acoustics, signal processing in acoustics as well as our scientific exploration at the intersection of cutting edge research and traditional architecture/music culture. This paper illuminates the evolution and growth of the Graduate Program.

Introducing acoustics as music in the interdisciplinary and inclusive classroom through ski-hill graph pedagogy to teach the meter fundamentals as sound (psychoacoustics)

Although music is sound (acoustics) and listeners experience the physics of acoustics as music, the meter of most music textbooks is the notated meter signature and group of beats notated in ‘measures’ on the page with vertical bar lines. Notation-based representation of the meter is antiquated music theory because new research in acoustics, cognitive neuroscience, and critically music theory (Cohn, 2020) informs otherwise. Cohn’s modern meter theory, a distillation of contemporary meter theory from North America, is the first comprehensive meter theory that acknowledges the meter's psychoacoustic experience and augments notation-based understandings of the meter through the meter the fundamental mathematics of the Ski-hill graph. This paper is a music teacher’s response to the availability of modern meter theory’s Ski-hill graph to represent the meter's psychoacoustic (mind and body) experience. The paper illustrates how listeners articulate their quantification of low meter frequencies such as the duple meter in sets of pulses in ratio 2:1 initiated by 1.2 hz and 2.4 hz experienced concurrently. Also, the triple meter sets of pulses in ratios 3:1 0.8 hz and 2.4 hz (Nozaradan et al., 2011).

Graduate studies in acoustics at the University of Nebraska – Lincoln within the College of Engineering

Those interested in pursuing graduate studies and conducting research in acoustics are invited to learn more about opportunities at the University of Nebraska – Lincoln (UNL) within the College of Engineering. Dr. Lily Wang and Dr. Erica Ryherd work on architectural acoustics and noise control topics (http://nebraskaacousticsgroup.org ) within the Durham School of Architectural Engineering and Construction, based at UNL's Scott Campus in Omaha. Dr. Jinying Zhu in Civil and Environmental Engineering (also based on UNL’s Scott Campus in Omaha) is active in structural acoustics, using ultrasonic waves for concrete evaluation (https://engineering.unl.edu/cee/faculty/jinying-zhu/). Dr. Joseph Turner in Mechanical and Materials Engineering (based at UNL’s City Campus in Lincoln) focuses on ultrasound propagation through complex media for quantitative characterization of materials/microstructure (http://quisp.unl.edu ). This poster presents the graduate-level acoustics courses and lab facilities at UNL within the College of Engineering, and highlights the research interests and achievements of our faculty, graduates, and students. Extracurricular experiences are available through an Acoustical Society of America student chapter based on the Scott Campus and collaborations with Boys Town National Research Hospital.

The graduate program in acoustics at Penn State

The Graduate Program in Acoustics at Penn State offers graduate degrees (M.Eng., M.S., Ph.D.) in Acoustics, with courses and research opportunities in a wide variety of subfields. Our 820 alumni are employed around the world in a wide variety of military and government labs, academic institutions, consulting firms, and consumer audio and related industries. Our 40+ faculty from several disciplines conduct research and teach courses in structural acoustics, nonlinear acoustics, architectural acoustics, signal processing, aeroacoustics, biomedical ultrasound, transducers, computational acoustics, noise and vibration control, acoustic metamaterials, psychoacoustics, and underwater acoustics. Course offerings include fundamentals of acoustics and vibration, electroacoustic transducers, signal processing, acoustics in fluid media, sound and structure interaction, digital signal processing, experimental techniques, acoustic measurements and data analysis, ocean acoustics, architectural acoustics, noise control engineering, nonlinear acoustics, outdoor sound propagation, computational acoustics, biomedical ultrasound, flow induced noise, spatial sound and three-dimensional audio, and the acoustics of musical instruments. This poster highlights faculty research areas, laboratory facilities, student demographics, successful graduates, and recent enrollment and employment trends for the Graduate Program in Acoustics at Penn State.