bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase-locked loops in acoustic analysis
Authors: Helffrich Jerome , Fulop Sean A.
Published: June 2017

Tracking of signal frequency and/or phase is made much more challenging by the presence of “rapid” frequency or phase changes in a signal—occurring in a time short compared to the amount of frequency shift: Δf×Δt << 1. In these scenarios, the usual Fourier decomposition does not provide detail sufficient to tell what is going on. Although there are time-frequency tricks one can use (such as the reassigned spectrogram, or wavelet analysis), these do not provide simple answers to the question of what is the phase as a function of time, and they do not track the instantaneous frequency as effectively as is wanted. An interesting solution from the realm of electrical engineering is provided by the phase-locked loop (PLL) detector: a construct that takes the input signal and tries to phase lock an on-board oscillator to it. It turns out that this process is surprisingly effective at tracking instantaneous frequency/phase while discarding noise if an initial estimate of the target signal frequency is known. We present examples of the superior frequency and phase tracking provided by a PLL approach, including the extremely brief chirps produced by electric fish, and the forensic detection of editing cuts in audio samples.
Supervised learning in voice type discrimination using neck-skin vibration signals: Preliminary results on single vowels
Authors: Lei Zhengdong , Li-Jessen Nicole Y. , Mongeau Luc
Published: June 2017

Discrimination between normal and pathological voice is a critical component in laryngeal pathology diagnosis and vocal rehabilitative treatment. In the present study, a portable miniature glottal notch accelerometer (GNA) device with supervised machine learning techniques was proposed to discriminate between three human voice types: normal, breathy, and pressed voice. Fourteen native American English speakers who were wearing a GNA device produced five different English single vowels in each of the three voice types. Acoustic features of the GNA signals were extracted using spectral analysis. Preliminary assessments of feature discrepancy among different voice types were made to present physical clues of discrimination. The linear discriminant analysis technique was applied to reduce the dimensionality of the raw-feature vector of the GNA signals. Maximization of between-class distance and minimization of within-class distance were synchronously achieved. The voice types were then classified using several supervised learning techniques, such as Linear Discriminant, Decision Tree, Support Vector Machine, and K-Nearest Neighbors. A classification accuracy of up to 91.0% was achieved. One mapping model from voice input to type output was eventually obtained based on the training set, so as to make predictions with new data in the future work.
Achievements and challenges in audio-based modeling of construction job sites
Authors: Rashidi Abbas , Davenport Mark A. , Anderson David V. , Cheng Chieh-Feng , Sabillon Chris A.
Published: June 2017

Construction job-sites are noisy workplaces and construction equipment and machines create discrete sound patterns while performing their daily operations. Construction engineers usually considered job site noise as a negative phenomenon, but if processed properly, the generated sound patterns could be used as a rich source of information for analyzing ongoing operations at job-sites. This paper presents the current research efforts of the authors regarding initiating and developing an audio-based model for analysis and modeling of construction operations. The audio-based model is based on placing single or multiple microphones at the jobsite, recording the developed sounds patterns, and using various techniques for processing the recorded audio files and detecting and recognizing different operations taking place at the jobsite. The implemented techniques include noise removal and signal enhancement, source separation, signal processing and machine learning algorithms. The paper also discusses about the necessary hardware settings (number, type and locations of microphones). The results of using the proposed system can be used by construction managers for several purposes including productivity analysis, project scheduling, differentiating between idle and active times of machine, etc. The authors also present several case studies from construction job sites to illustrate how the system works in real world settings.
Spatial-division-multiplexing (SDM) in time-variant channel based on vector adaptive time-reversal technique
Authors: Lu Dian , Sheng Xueli , Shi Yali , Yu Hanjun , Guo Longxiang , Yin Jingwei
Published: June 2017

In the field of multistatic remote detection for underwater target, as a time-variant and multi-path channel interfered by environmental noise, underwater acoustic environment limits the spatial share of channel and poses a great challenge against spatial-division-multiplexing(SDM) in multistatic detection. In this paper, a kind of method of spatial-division-multiplexing(SDM) in time-variant channel based on vector adaptive time-reversal technique is proposed. By using time-reversal technique, multi-path structure of channel is efficiently restrained ; Applied adaptive filtering, time-variant characteristic of channel is effectively suppressed; With single vector hydrophone, spatial focus of target echoes and noise interference suppression is accomplished by spatial filtering. Finally, excellent results are performed in spatial-division-multiplexing(SDM) of multistatic detection, supported by the experimental simulation.
Ultrasonic tomography for multiphase flow characterization
Authors: Li Weichang , Deffenbaugh Max , Noui-Mehidi Mohamed
Published: June 2017

Characterizing multiphase flow dynamics and estimating phase composition are important in many applications including oil/gas production. Conceptually ultrasonic travel-time tomography is an appealing method. It estimates flow phase composition by mapping out the sound speed distribution over a cross section or volume traversed by a large number of travel paths. However, low sound speed contrast over multiphase mixtures imposes high accuracy requirement in travel time estimation which can be especially challenging in the presence of dispersion and multipath interference. On the other hand, high impedance contrast between phases, such as at gas/liquid interfaces, introduces significant losses and hence leads to reduced signal versus noise ratio. In this talk we first provide a characterization of the signal structure based on both numerical wave propagation modeling and lab test data, then we analyze the sensitivity and accuracy requirement for travel time estimation using several different approaches, and finally we evaluate the performance of flow imaging and phase estimation for several common compositional scenarios.
Acoustic analogs for the characterization room electromagnetics
Authors: Gandhi Pratik , Thompson Charles , Chandra Kavitha
Published: June 2017

In indoor wireless communication the radio channel is comprised of the direct and diffuse multipath components. As in the acoustics case these diffuse components are the result of non-specular and random scattering. This state-of-affairs is particularly problematic for short-range millimeter wavelength radio system. The Eyring model has recently been shown to be effective in modeling the electromagnetic power decay profile in rooms. In this work temporal decay rates of the energy in coupled spaces is considered. The role which inter-room transmission and energy absorption play on the power decay profile will be examined. Special session: Acoustics Network Protocol, Underwater Acoustic Communications. Pacs Number: 43.60.Dh, 43.38.Si
Measurement and analysis of a piezoelectric mirror shifter impulse response using self-correcting synthetic-heterodyne demodulation based Michelson interferometer vibrometer with gain and phase control feedback
Authors: Connelly Michael J. , Galeti Jose H. , Kitano Claudio
Published: June 2017

Laser Doppler vibrometry is often employed for non-contact vibration measurements. A test beam scattered from a target is interfered with a reference beam on a photodiode and the resulting signal is processed to determine the target vibration. Most commercial vibrometers use a phase modulator in one branch of the interferometer. The requirement for a phase modulator can be removed by the use of synthetic-heterodyne demodulation. The optical source is a sinusoidal current modulated laser diode resulting in a frequency modulation of the input lightwave. The photocurrent has the form of the cosine of a carrier at the modulation frequency plus the dynamic phase difference between the beams, the time differential of which is proportional to the vibration. The detected signal spectrum comprises bands centered at integer multiples of the modulation frequency, which are processed to retrieve the vibration. We describe a new self-correcting synthetic-heterodyne technique employing phase and gain feedback, which is significantly less sensitive to the received optical power. The system, which has a frequency range of 0.2-9 kHz, is used to measure the impulse response of a piezoelectric mirror shifter. The vibration signal is analyzed using Hilbert transform techniques to determine the shifter resonant frequencies and decay rates.
Capturing Bragg-scattered structural waves with Digital Image Correlation for underwater localization applications
Authors: Joffre Dagny , Sabato Alessandro , Niezrecki Christopher , Avitabile Peter
Published: June 2017

Bragg scattering is a well-known occurrence in structures containing periodically spaced obstructions. A urethane test panel, with periodically spaced aluminum ribs, was built to study the possibility of using Bragg scattered responses to localize acoustic underwater signals. The presence of Bragg scattered waves may allow the size of an array to be reduced without a loss in the array gain. The measured structural response of the test panel to acoustic excitations can be converted into a wavenumber spectrum; the wavenumber spectrum can then be used to calculate the incident angle of the original acoustic excitation. Precise bearing estimates require high spatial resolution measurements. Digital Image Correlation (DIC), which measures full-field displacement in a structure, may provide the high spatial resolution necessary for improved bearing angle estimation. A study was conducted comparing the wavenumber spectra of the test panel calculated from DIC measurements, laser vibrometer measurements, and from theoretical FEM results.
Optical methods for modeling and experimental detection of sound sources behind windows
Authors: Borel-Donohue Christoph , Habtour Ed , Goldman Geoffrey H.
Published: June 2017

Detecting sound from a distance is not a novel concept and laser vibrometers are often used for this purpose. A potentially better method is to measure the reflection of the usually stationary environment in a vibrating window. Experiments were conducted to capture high-speed video of vibrating windows with sound sources located inside a building. Low frequency vibrations produced by a speaker operating between 19 and 37 Hz were clearly visible on high contrast reflections under a very limited set of conditions. To better understand the limitations of the method in terms of variabilities of potential scenarios with sound, window, optical reflection, camera and analysis methods a parallel modeling effort was initiated. The detection of sound using optical methods can vary with sound source parameters (e.g. frequency, spectrum, amplitude, …), the window structure (glass thickness, number of panes, elasticity,…), the character of the reflected environment (contrast ratio, intensity,…), the measuring equipment (camera frame rate, spatial resolution, dynamic range, integration time, noise level,…), and the analysis methods (short term Fourier analysis window size, apodization, preprocessing steps,…). This talk will highlight some of the findings to determine the feasibility of optical detection of sound sources behind windows.
Detection of vibrations on windows and doors excited by a speaker using video cameras
Authors: Goldman Geoffrey H. , Borel Christoph C.
Published: June 2017

Algorithms were developed and tested to estimate acoustic coupled vibrations on doors and windows in a small building using data from commercial video cameras. The building was excited with a speaker that emitted low frequency tones. Image processing based algorithms were developed to estimate the frequency, amplitude, and signal-to-interference-plus-noise ratio (SINR) of the tones. Sensors such as Laser Doppler Vibrometers (LVDs) and accelerometers are much more sensitive than video cameras for measuring small vibrations and have a higher cutoff frequency. However, video cameras are ubiquitous, passive, and can potentially monitor a large area. Their performance is limited by the target range due to increased pixel size and atmospheric turbulence, lighting conditions, the contrast of the object of interest and the sample rate of the camera. Given these limitations, there are still potential new applications and niches for using video cameras to remotely measure vibrations of objects.
Good noise, bad noise: A tricky case of balancing risk of physical injury against acoustic disturbance for marine mammals and tidal energy devices
Authors: Wilson Ben , Marmo Brett , Lepper Paul A. , Risch Denise , Benjamins Steven , Hastie Gordon , Carter Caroline
Published: June 2017

Tidal-stream turbines are a promising source of renewable electricity worldwide. These technologies are sufficiently new that only single test devices have been deployed with arrays imminent. Being new, their interactions with marine organisms are poorly understood and the risk of large marine vertebrates colliding with their moving blades is a consenting and ecological concern. Operational noise is also considered a disturbance threat but under what circumstances is poorly defined. Further, the threats of collision and turbine noise may be inversely correlated with animals needing to hear turbines to avoid them. Consequently, there have been proposals to add extra-noise by fitting turbines with acoustic deterrents to warn or scare animals away. In this talk we examine the acoustic interactions between marine mammals and tidal turbines. The interactions are complex and depend on turbine source levels, ambient sound, propagation in moving water, sensory abilities, swim speeds and diving behaviour. In addition, the occurrence of turbines in arrays adds further complexity as responses to one turbine will impact collision risk with another. We then consider the options for and implications of adding additional warning sounds but such quick fixes might have unintended consequences that either increase collision risk or lead to undesirable avoidance.
Operational noise from tidal turbine arrays and the accessment of collision risk with marine mammals
Authors: Marmo Brett
Published: June 2017

The ability for marine species to detect and thereby avoid potentially harmful collision with the moving parts of a tidal stream turbine depends on relative levels of the ambient sound with the acoustic emissions from the turbine. Tidal streams targeted for exploitation by renewable energy converters are by their nature highly energetic environments often with high ambient sound levels. Commonly the first time that the operational sound from new tidal turbines can be measured is after it has been installed and is already interacting with animals in the marine environment. A modelling solution is therefore required to estimate whether marine animal will be able to hear and avoid contact with turbines. An acoustic-structural interaction model is used to calculate the acoustic output of tidal turbines. The cumulative sound of an array of tidal turbines and its dependence on bathymetry is calculated using a parabolic equation code. Modelled and measured sound pressure levels give information on potential upstream warning distances/times for animals which help us consider collision risk.
Noise impact assessment on Indo-Pacific Humpback Dolphin in the habitat of the East Taiwan Strait during the first two pile driving activities of demonstration offshore wind farm
Authors: Chen Chi-Fang , Wang Wei-Jay , Wu Chih-Hao , Hu Wei-Chun , Chen Nai-Chang , Hwang Wei-Shien , Chou Lien-Sian , Guan Shane , Lin Sheng-Fong , Lin Derrick
Published: June 2017

Foundation piles of the first two wind turbines were driven off the coast of Miaoli, Taiwan in 2016. However, that area is also the habitat of the critically endangered Eastern Taiwan Strait (ETS) population of Indo-Pacific humpback dolphin (Sousa chinensis). To assess potential noise effects from pile driving on the humpback dolphins, we collected underwater noise data during the construction and found that the sound pressure level (Lrms) at 750m was less than 180dB re 1μPa and the peak sound pressure (Lpk, flat) was less than 190 dB re 1μPa. We also presented recommendations of noise and marine mammal monitoring for future pile driving activities. It includes an exclusion zone of radius 750m from the piling location and the peak sound pressure (Lpk, flat) not to exceed 190~220 dB re 1μPa at 750 m distance, and an observation zone extends to 1500m radius where both marine mammal observers and passive acoustic monitoring are posted. [This work was sponsored by Ministry of Science and Technology of Taiwan (105-3113-E-002 -002 -CC2), Taiwan Bureau of Energy and Industrial technology Research Institution (05HZT56002), and U.S. Marine Mammal Commission’s Research and Conservation Grant.]
Broad-scale acoustic monitoring for cetaceans and underwater noise in relation to offshore wind farm construction in Scotland
Authors: Brookes Kate L. , Edwards Ewan , Merchant Nathan D. , Davies Ian
Published: June 2017

Marine construction projects, such as offshore wind farms and port developments often use techniques that produce significant levels of noise underwater, which could have effects on marine wildlife. Marine Scotland is the government body responsible for regulating these activities in Scottish waters and for ensuring that wildlife populations are protected in line with legislation. Large scale offshore wind farm construction will begin to take place off the Scottish east coast in 2017, using piled foundations. To monitor for potential broad scale changes in distribution of protected cetacean species during construction activities, Marine Scotland have deployed an array of 30 click detectors and 10 broadband acoustic recorders across the Scottish east coast each summer since 2013. Here we present baseline distributions for dolphins and harbour porpoises, along with ambient noise levels recorded concurrently. Dolphin detections across the monitored area are highly variable, with some locations that are clearly favoured. Harbour porpoise are ubiquitous and in more than 60% of locations are detected on 100% of monitored days. This is likely to mean that there is more power to detect changes in porpoise distribution in relation to offshore wind farm pile driving than for dolphins.
Acoustic characterization of wave energy converters
Authors: Polagye Brian L. , Murphy Paul , Cross Patrick , Vega Luis
Published: June 2017

Wave energy converters produce sound as a consequence of their operation, but the specifics are not well-understood. Here, we present observations of two point-absorbing wave energy converters deployed at the US Navy’s Wave Energy Test Site in Kaneohe, HI. Measurements are obtained by free-drifting instrumentation packages which acoustical isolate the hydrophone from the surface expression to minimize masking by flow-noise (i.e., pseudo-sound generated by relative motion between hydrophone and water) and self-noise (i.e., propagating sound generated by the instrument package). Observations suggest that wave energy converters of different designs, even within the general class of point absorbers, produce different stereotypical sounds. Further, during normal operation, sound signatures can change substantially with sea state as new sound generation mechanisms come into play. One example of this is wave breaking around a shallow-hulled point absorber when waves exceed a critical steepness. The sound from bubble collapse is detectable up to several hundred kHz, whereas, below this critical steepness, wave converter sound is only detectable up to ten kHz. Finally, wave energy converter sounds are contextualized relative to other natural and anthropogenic sound sources to qualitatively explore their potential effects on marine animals.
Acoustic life cycle assessment of offshore renewables—Implications from a wave-energy converter deployment in Falmouth Bay, UK
Authors: Blondel Philippe , Walsh Jodi , Garrett Jo K. , THIES Philipp R. , GODLEY Brendan J. , Witt Matthew J. , Johanning Lars
Published: June 2017

Marine Renewable Energy is developing fast, with hundreds of prototypes and operational devices worldwide. Two main challenges are assessing their environmental impacts (especially in near-shore, shallow environments) and ensuring efficient and effective maintenance (requiring specialised ships and fair weather windows), compounded by the lack of long-term measurements of full-scale devices. We present here broadband measurements (10 Hz to 32/48 kHz) acquired at the Falmouth Bay Test site (FaBTest, UK) from 2010 onwards, for a 16-m ring-shaped Wave Energy Converter, in waters up to 45 m deep. This period covers baseline measurements, including shipping from the neighbouring English Channel, one of the busiest shipping lanes in the world (ca. 45,000 ship transits annually) and the full period of installation and energy production, including maintenance episodes. Acoustic signatures are measured as Sound Pressure Levels (e.g. for impacts) and time/frequency variations (for condition-based monitoring via Acoustic Emissions). They change through time, depending on weather and modes of operation. Long-term measurements are compared with modelling of potential variations in this complex environment and with laboratory experiments. These are used to outline the varying acoustic contributions through the life cycle of a typical wave energy converter, yielding insights for other wave devices in other environments.
Underwater operational noise level emitted by a tidal current turbine and its potential impact on marine fauna
Authors: Lossent Julie , gervaise cedric , Iorio Lucia D. , Folegot Thomas , Clorennec Dominique , Lejart Morgane
Published: June 2017

Marine renewable energy development raised concerns over the impact of underwater noise. We assessed the acoustic impacts of an operating tidal current turbine (Paimpol-Bréhat site, France) on marine fauna. The turbine’s source level (SL) was estimated using 19 acoustic drifting transects at distances between 100m to 2400m from the device. SL ranges from 118 to 152dBre1μPa@1m in the third-octave bands at frequencies between 40 and 8192Hz, a noise level comparable to the one emitted by a 19m boat travelling at 10kt. The SL was used to estimate the impact of the turbine’s noise based on acoustic propagation simulations. The overall acoustic footprint of the device corresponds to a disk of 350 meters radius. Our results showed that within this footprint, physiological trauma is improbable but behavioral disturbance may occur up to 350m around the device for marine mammals (impact limited by the footprint area), and 55m, 5m and 5m respectively for pollocks, sea basses and a shrimp species. Feedbacks from this study show that the assessment of TTS and PTS risk areas for marine mammals is rather mature, but there are still many uncertainties about the assessment of risk areas for behavioral disturbance and masking for fishes and marine invertebrates.
Autonomous underwater vehicle self-localization using a tetrahedral array and passive acoustics
Authors: Rypkema Nicholas R. , Fischell Erin M. , Schmidt Henrik
Published: June 2017

The recent development of very low-cost, miniature autonomous underwater vehicles (AUVs) has lowered the barrier toward the deployment of multiple AUVs for spatially distributed sensing. However, these AUVs introduce size, power, and cost constraints that prevent the use of traditional approaches for vehicle self-localization, such as Doppler velocity log (DVL)-aided inertial navigation. In this work, we describe a system that estimates the vehicle's position relative to a single acoustic transmitter. The transmitter periodically outputs a linear up-chirp that is synchronously recorded by a tetrahedral ultra-short baseline (USBL) hydrophone array on the AUV. Real-time 3D phased-array beamforming and matched filtering is performed on-board the vehicle, and integrated with AUV pitch-roll-heading to calculate azimuth, inclination, and range measurements to the transmitter. Finally, a particle filter incorporates these measurements with vehicle speed estimates and a motion model to generate a positional likelihood for the acoustic transmitter relative to the AUV. This system enables vehicle self-localization in the case where the transmitter is stationary, and is entirely passive on the vehicle, allowing multiple AUVs to localize using a single transmitter. We describe the processing pipeline of our system, and present results from AUV field experiments. [Work supported by Battelle, ONR, Lincoln Laboratory and DARPA.]
Adaptation of acoustic transmission rates to optimize unmanned underwater vehicle communications
Authors: Seto Mae L. , Nams Dainis
Published: June 2017

A framework for on-line characterization of in-water in situ acoustic transmission conditions, and intelligent adaptation of transmission rates to these conditions, is implemented on-board an unmanned underwater vehicles (UUV). The objective is to optimize use of the acoustic communications channel during collaborative shallow water missions with other UUVs. The software database uses relatively little bandwidth to track the success of transmitted packets, providing operator data tracking in addition to communications layer visibility into current channel conditions. The rate selector chooses the optimal transmission rate based on an adaptive distance bin approach. Measurable results are improvements in bandwidth, reduction in modem power usage, and increased visibility into data success compared to traditional, constant-rate acoustic communication patterns. The algorithm, its implementation, and recent in-water validation results are presented.
Noise cancellation for an autonomous underwater vehicle-towed thin line array through recursive adaptive filtering
Authors: Cheng Chi , Pallayil Venugopalan
Published: June 2017

The digital thin line array (DTLA) developed at ARL, National University of Singapore have been integrated and tested with different autonomous underwater vehicles (AUV) and tested in the field to detect, localize and track underwater targets. For tow speeds not exceeding 4knots, it has been found that the flow noise is not a major contributor to performance reduction. However, noise generated by the propulsion system of some of the AUVs presents a major interferer to the detection capabilities of DTLA, especially, at low ambient noise conditions. The method proposed in the literature for platform noise cancellation employs a single adaptive filter. The number of the filer taps required in this case would be more than thousands due to the multi-path nature of the AUV noise in the environment of interest and the solution is difficult to converge. To mitigate the above problem, we propose a recursively adaptive strategy, which employs the least mean-square (LMS) algorithm. Our strategy is based on the fact that the underwater channel is sparse for the DTLA and using a reference sensor close to the AUV propulsion system. The noise peaks are eliminated through recursive adaptive filter operations after cross correlating the noise signal at each sensor with the reference. The proposed method has been verified through simulations and we propose to apply this technique in a practical application.
Quiet micro boats: An inexpensive acoustic sensing suite
Authors: Bogdan Caitlin , Palladino Robert V. , Magliula Elizabeth A. , McDaniel James G.
Published: June 2017

The Quiet Micro Boat [QMB] is an inexpensive acoustic sensing platform constructed from off-the-shelf hardware and software components to allow for a fleet of acoustic sensors that can be deployed into real-world sensing scenarios at a low cost. The QMBs operate using a Beaglebone Black as a central processor, with jet propulsion generated by bilge pumps for robust ocean operation. Acoustic data are collected through a hydrophone which interfaces with the BBB, and data is centralized using the XBee and Zigbee radio mesh configuration. The talk will focus on the hardware costs and performance, discuss the design cycle and decisions, and feature some of the acoustics projects that have been tested on the devices. [Work sponsored by the Naval Sea Systems Command (NAVSEA) Naval Engineering Education Consortium (NEEC) Contract Number N00174-15-C-0022 and by the Raytheon Advanced Studies Fellowship.]
Automatic target recognition and geo-location for side scan sonar imagery
Authors: Scarafoni Daniel , Bockman Alexander , Chan Michael
Published: June 2017

Ocean and lake floor survey is most efficiently conducted by active sonar owing to its favorable propagation range under water relative to other sensing modalities. Range however must be traded for resolution, yielding sonar return imagery that challenges both operator and machine to match returns to specific objects. In the case of certain objects, time-range extent in echo imagery may be exploited by machine learning detection and classification methods. This talk describes the success of such a method when applied to data collected from a low cost autonomous platform. Further capabilities such as decision support and detection geolocation are discussed. [This material is based upon work supported under Air Force Contract No. FA8721-05-C-0002 and/or FA8702-15-D-0001. Any opinions, findings, conclusions, or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the U.S. Air Force. Presentation may contain distribution limited material.]
Reproducibility of a metric for sound reflectivity
Authors: Doggett Felicia , San Souci Sooch
Published: June 2017

Past attempts at developing a system able to quantify the sound reflectivity of a surface have been hindered by the shear difficulty of repeatability and reproducibility. Where and why these challenges arise, and how they can be overcome is discussed. Sound fields resulting from direct sound energy projected at various incident angles toward materials and assemblies are compared as well as how laboratory setups and specimen changeovers can affect outcomes. Can precision be increased and bias avoided? A proposed system based on software driven microprocessors and robotic precision is very fast with a high degree of precision performing at less than 0.1 mm error over 50 repeated runs. The performance in terms of repeatability and reproducibility are approximately equivalent to today's ink jet printers. As a recognized acoustic metric, the Sound Reflectivity Index could provide vital data that would accompany all products. For acousticians, a higher order of accuracy would be possible in designs involving envelopment, early reflections, speech comprehension, speech privacy, sound enhancement, and general room acoustics.
The perceptual evaluation of acoustical environments I: Simulated environments
Authors: Weinzierl Stefan
Published: June 2017

The successful design and development of numerical models for the sound propagation in rooms crucially depends on the existence of appropriate measures for the quality assessment of the modeling results. In the perceptual domain, these should include single-number measures for the overall assessment of the simulation as well as differential measures, enabling experts to identify specific shortcomings in the selected modeling approach and its implementation. In the SEACEN consortium, the “authenticity” and the “plausibility” of virtual acoustic environments has been established, measuring the perceived identity with an external (given) or internal reference. Moreover, a Spatial Audio Quality Inventory (SAQI) was developed by a focus group of experts for virtual acoustics, as a metric for the differential diagnosis of virtual environments.
The perceptual evaluation of acoustical environments II: Natural environments
Authors: Weinzierl Stefan
Published: June 2017

The perceptual evaluation of natural acoustic environments requires an assessment of the “room acoustical impression.” After some theoretical considerations on the nature of this perceptional construct and the shortcomings of existing tools, we present a new, empirically substantiated approach for the development of a corresponding measuring instrument. It relies crucially on the room acoustical simulation of a representative pool of acoustical environments for speech and music and their auralization for different acoustical sources. The resulting room acoustical quality inventory, together with a database of room acoustical models and their monaural and binaural transfer functions, can be used as a ground truth for room acoustical analysis and perception.
Psycho-acoustic evaluation of physically-based sound propagation algorithms
Authors: Rungta Atul , Klatzky Roberta , Lin Ming C. , Manocha Dinesh
Published: June 2017

Recently, many physically accurate algorithms have been proposed for interactive sound propagation based on geometric and wave-based methods. In terms of these applications, a key question arises whether the improved physical accuracy of these algorithms offers perceptual benefits over prior interactive methods? In this work, we present results from two studies that compare listeners' perceptual response to both accurate and approximate propagation algorithms that are used to simulate two key acoustic effects: diffraction and reverberation. For each effect, we evaluate whether increased numerical accuracy of a propagation algorithm translates into increased perceptual differentiation in interactive environments. Our results suggest that auditory perception indeed benefits from the increased accuracy, with subjects showing better perceptual differentiation when experiencing the more accurate propagation method. The diffraction experiment exhibits a more linearly decaying sound field (with respect to the diffraction angle) for the accurate diffraction method, while the reverberation experiment shows that more accurate reverberation results in better assessment of room volume and acoustic distance perception. In case of room volume, accurate reverberation, after modest user experience, results in a near-logarithmic response to increasing room volume. Finally, in the case of acoustic distance perception, accurate reverberation shows less distance compression as compared to an approximate, filter-based reverberation method.
A room acoustical quality inventory
Authors: Lepa Steffen , Weinzierl Stefan
Published: June 2017

In a two-step procedure, a new psychological measuring instrument has been developed for the acoustical perception of room acoustical environments for speech and music. As a first step, an expert focus group of room acoustical scholars and consultants was formed in order to reach a consensus on a vocabulary as complete as possible to describe room acoustical qualities. In a second step, this inventory was used for the evaluation of 35 different simulated room acoustical environments presented by binaural synthesis to 190 subjects of different age and expert level. Based on the ratings of this room sample, a comprehensive psychometric analysis was performed in order to evaluate the preliminary item battery with respect to reliability, discriminative power, and redundancy. The resulting room acoustical quality inventory, together with the database of room acoustical models as well as their monaural and binaural transfer functions and their perceptual evaluation, can be used as a ground truth for the validation of existing and newly developed room acoustical parameters.
Inter-aural cross-correlation measured during symphony orchestra performance in big concert halls
Authors: Skalevik Magne
Published: June 2017

Spatial impression in concert hall listeners is known to depend on lateral reflections causing differences between the sound at the left ear and the right ear. Such differences can be measured, e.g., by the so-called inter-aural cross-correlation IACC in a binaural signal pair, i.e., a signal pair from microphones placed in the ear canal entrances. IACC data from binaural impulse responses (BRIR) are commonly reported. In contrast, little attention has been paid to running IACC, i.e. IACC(t), during music performance. Therefore, in 2011 this author launched the Binaural Project in 2011 in order to collect binaural signal data from concerts with symphony orchestras. An analysis of IACC(t) from more than 600 minutes of binaural recordings during concerts in many big concert halls is presented. Several famous halls, including Boston Symphony Hall, are included in the data. Among the questions to be answered are Can we observe from the data that concert halls make a difference to IACC(t)? If so—is this variation small or big compared to the variation from one moment to another, bar to bar, movement to movement, from one orchestra to another, and so on? On the other hand, if we cannot observe significant hall-to-hall differences, several new questions would arise, including How can we maintain that listeners are able to perceive hall-to-hall differences in ASW and LEV? And why do not the reported hall-to-hall differences in IACC from impulse responses (ISO-3382) make an observable difference to running IACC(t)?
Audio-visual room perception: Cross-modal and interaction effects put to test
Authors: Maempel Hans-Joachim , Horn Michael
Published: June 2017

The perception of rooms involves different modalities, particularly hearing and sight. Fundamental issues such as the acoustical and optical shares in certain perceptual features have, however, not been experimentally addressed yet. We investigated to what extent the acoustical and optical properties of performance rooms influenced auditory and visual features. Specifically, cross-modal effects and interaction effects were a matter of particular interest. We also quantified the respective proportion of acoustical and optical information accounting for the perceptual features. The main preconditions for such an undertaking are the dissociation of the acoustical and optical components of the stimuli, the commensurability of these components, and rich cue conditions. We acquired binaural room impulse responses and panoramic stereoscopic images of six rooms in order to recreate these rooms virtually, and added recordings of both a music and a speech performance by applying dynamic binaural synthesis and chroma-key compositing. By the use of a linearized extraaural headset and a semi-panoramic stereoscopic projection system we presented the scenes to test participants and asked them to rate unimodal features such as loudness, highs, lows, clarity, reverberance, and envelopment as well as brightness, contrast, color intensity, and hue. The statistical analyses indicate a straight-forward processing of low-level features.
Azimuthal localization in 2.5D near-field-compensated higher order ambisonics
Authors: Winter Fiete , Hahn Nara , Wierstorf Hagen , Spors Sascha
Published: June 2017

Sound Field Synthesis approaches aim at the reconstruction of a desired sound field in a defined target region using a distribution of loudspeakers. Near-Field Compensated Higher Order Ambisonics (NFCHOA) is a prominent example of such techniques. In practical implementations different artifacts are introduced to the synthesized sound field: spatial aliasing is caused by the non-zero distance between the loudspeakers. Modal bandwidth limitation is a well-established approach to reduce spatial aliasing in 2.5D NFCHOA, but introduces temporal and spectral impairments to the reproduced sound field which strongly depend on the relative position to the center of modal expansion. Also, the dimensionality mismatch in a 2.5D synthesis scenario results in a different amplitude decay compared to the desired sound field. Listening experiments already investigated the azimuthal localization in 2.5D NFCHOA. It is however unclear, in how far individual artifacts caused by spatial sampling, modal bandwidth limitation, and the 2.5D dimensionality mismatch contribute to these localization impairments in particular. Within this contribution a mathematical framework is used together with binaural synthesis to simulate the individual effect of each artifact on the ear signals. Humans' performance is approximated by a binaural model for azimuthal localization.
Archaeological auralization as fieldwork methodology: Examples from Andean archaeoacoustics
Authors: Kolar Miriam A.
Published: June 2017

Auralization, the computational rendering of sound for listeners, enables archaeoacoustical reconstructions. In archaeoacoustics research, computational tools and analyses frequently enmesh with human performance. Broadening the definition of archaeological auralization to encompass the investigative process of specifying and enacting the re-sounding of archaeological spaces, objects, and events positions auralization as a methodology for the sensory exploration of anthropological research questions. A foundational tool for archaeoacoustical and archaeomusicological fieldwork, auralization allows contextualized testing and measurement of spatial and instrumental acoustics, along with their perceptual evaluation. Case-study examples from Andean archaeoacoustics research include auralizations of reconstructed architectural acoustics, and in-situ loudspeaker playback of recorded performances of 3,000-year-old conch shell horns, delivered as auditory perceptual experiment stimuli within the extant ceremonial architecture at Chavín de Huántar, Peru. Performed plaza auralizations at the Inka administrative city Huánuco Pampa re-enacted sound transmission dynamics in that Pre-Columbian public space, enabling present-day listeners to evaluate verbal intelligibility, among other tests. As a fieldwork methodology, archaeological auralization is both process and product: the specification and physical sounding of concepts and data, to be observed and evaluated in relationship with archaeological materials and knowledge.
The acoustics and sound environments of Early Delta Blues
Authors: Howell Mark H.
Published: June 2017

As part of a larger investigation into the archaeological origins of the blues, I seek to re-create the sound environments that surrounded and informed the initial emanations of this important American music genre. This study is warranted because the music has had such a pronounced influence on global musics, as well as on broader sociological concerns like race, regionalism, nationalism, capitalism, and gender. It is also of value for archaeo-acoustic studies in that it concerns a study of an archaeo-historic site that is not in the deep past. For the ASA meeting-forum I will report on two related acoustic processes: one is the digital reconstruction of the physical structures where the blues was first heard, such as wood-framed shotgun-shaped performance spaces (juke joints, general stores), some of which still exist in the Mississippi Delta (Po Monkeys near Merigold and Mary’s in Indianola), or can be archaeologically recovered (the general store at Dockery Farms); and the second process is a recreation of the sonic environment of the late 19th early 20th century south of the lower Mississippi river valley, including natural and anthropomorphic sounds. These steps precede a future goal, the archaeologically reconstructed instrumental and vocal sounds of incipient and early blues, allowing for a truer picture of this musical phenomenon than currently exists.
Üneholisunn: Proposal for a new descriptive language of sound
Authors: Benjamin Jeff
Published: June 2017

The apprehension of historic sound relies upon a philosophical shift from representation to presence: we do not need electronic capture to preserve sonic forms. In this paper, I will argue that most of the sounds we hear are old sounds, glazed with the patina of novelty. The dialog that persists between different fundamental conceptions of sound is instructive, but the assertion of sound as artifact, or sonifact (as a material thing that endures through time)provides a useful way of thinking about historic sound in particular. This points to the somewhat pressing need for an adequate descriptive language of sound, a colloquial way of expressing the abundance of sonifacts all around us. In this paper, and specifically pertaining to landscapes of industrial ruination, I intend to offer some suggestions for the possible development of such a language. After an initial description of this project, I will read a series of poems using these words to demonstrate a possible method to convey sonic information in the vernacular. Many of the root words for this agglutinative sonic language will be drawn from some of the world's disappearing languages.
Overview: Ecoacoustics for monitoring freshwater and marine biodiversity
Authors: Risch Denise , Parks Susan
Published: June 2017

Global marine and freshwater ecosystems are experiencing an unprecedented loss and re-distribution of biodiversity, due to far reaching effects of human activities, including accelerated climate change and over-exploitation. Such changes in aquatic diversity patterns will lead to shifting baselines with respect to species richness and distribution, which need to urgently be monitored. Due to its applicability in surveying remote areas over extended timescales, ecoacoustics play a vital part in monitoring such large-scale changes. Aquatic ecoacoustics is a field that is expanding rapidly alongside emerging underwater technologies, including gliders and real-time passive acoustic buoys, as well as analytical approaches for assessing ecosystem health. These tools can also be used to monitor changes in abiotic environmental factors, including precipitation and wind events, as well as contributions of anthropogenic noise to the overall soundscape. Concerns about the increasing impact of particularly long range and ubiquitous noise sources such as global shipping traffic or seismic surveys, necessitate approaches to monitor their relative influence on aquatic soundscapes. This review will examine the use of ecoacoustic approaches to monitor freshwater and marine environments, identify gaps of knowledge, and provide recommendations for future applications of ecoacoustic tools to aide in the conservation of freshwater and marine biodiversity.
Implantation of marine ecoacoustic indices
Authors: Radford Craig A.
Published: June 2017

Diversity measurement techniques can present logistical and financial obstacles to conservation efforts. Ecoacoustics has recently emerged as a promising solution to these issues, providing a mechanism for measuring diversity using acoustic indices, which have proven to be beneficial in terrestrial habitats. During summer in temperate north eastern New Zealand acoustic and traditional biodiversity surveys were conducted. Three ecoacoustic indices originally developed for terrestrial use were then compared to three species assemblage diversity measures and compared using Pearson correlations. Acoustic Complexity Index (ACI) was significantly correlated with Pielou’s Evenness (J’) and Shannon’s index (H’). Wind did not affect any of the acoustic indices. As anthropogenic noise was included in these investigations, both ACI and H were considered robust to its presence. However, all these relationships break down using recordings taken in winter even though the traditional diversity measures remains consistent. The development of marine acoustic indices is only in its early stages, but there are significant questions around trying to implant what has been achieved in terrestrial ecosystems rather than developing specific indices for the marine environment.