bluuebunny/crossref_metadata_2025 huggingface dataset:
Invariants of the time reversal operator for an elastic target in a water waveguide
Authors: Philippe Franck D. , Prada Claire , De Rosny Julien , Minonzio Jean-Gabriel , Fink Mathias
Published: May 2008

Detection and characterization of a target in shallow water is an active field of research. In general, in a waveguide, the dispersion is such that the frequency signature of a target cannot be extracted from a single backscatterd signal unless the waveguide properties as well as the target's position are known (Mignerey et al., JASA 1992 and Yang et al., JASA 1994). We propose to apply the Decomposition of the Time-Reversal Operator method to recover the target's signature in an unknown waveguide. Using a modal theory, we show that provided the target is far from the boundaries of the guide the first singular value of the time reversal operator is proportional to its signature. Using the same approach, the second singular value is shown to be proportional to the second derivative of the angular dependant form function which is a relevant parameter for target identification. Ultrasonic laboratory experiments are presented that confirm these theoretical results.
Building acoustics standards in the USA - ASTM and ISO
Authors: Browne Sean D. , Roy Kenneth P.
Published: May 2008

In the US most architectural design and acoustical performance specifications are based on the ASTM International standards for Construction/Building & Environmental Acoustics. Those standards are developed as a responsibility of ASTM International committee E 33 on Building & Environmental Acoustics. The US is of course a participating member in the development of ISO standards through the American National Standards Institute (ANSI), and this participation relative to standards in architectural acoustics is within ISO TC 43 SC2 which deals with building acoustics. The actual ISO standard development and voting responsibilities in the US rests with the ANSI Technical Advisory Group (TAG) to ISO TC43 SC2 which is delegated to ASTM International committee E 33.06 International Standards. This paper will present the process whereby international participation is involved in the development of both ASTM and ISO standards from the US perspective.
Prediction models for building performance - European need and world wide use
Authors: Gerretsen Eddy
Published: May 2008

The development of the unified European market made it necessary to create CE-marking to indicate a certain performance of products. For building products the performance had to enable the fulfilment of essential requirements by buildings, constructed with those products. This made it essential for acoustic requirements to standardize predictions models: the link between acoustic product performance and building performance. In the mean time all six parts of that standard (EN 12354) have been published and are used. Some parts have also been published as ISO standard (ISO 15712) indicating the wider interest in the subject. To be of use in Europe and elsewhere it is important that all types of building structures are covered and indeed work is going on to extend the models to lighter building elements, even more common outside Europe than within. Furthermore, a very important aspect of prediction models is the input data, hence an increased need of standards to determine product performance in an appropriate way. This is even more an item of world wide interest. So the existing standards, the current developments for improvement and the identified need for product standards will be addressed.
Comparison of ASTM and ISO sound absorption test methods
Authors: Bischel Marsha S. , Roy Kenneth P. , Greenslade Joan V.
Published: May 2008

A series of planned experiments has been conducted in which the differences between ASTM C423 and ISO 354 have been compared. These experiments focused on the differences in the two test methods, with the goal of identifying and understanding differences in the ultimate test results. A variety of acoustical ceiling tiles were tested in the same NVLAP-certified facility, generating data that cover a broad range of acoustical performance. The factors examined were: the effect of sample size on absorption; the effect of plenum depth on measured absorption; and the differences between the SAA and αw curves resulting from the two test methods. The results of these experiments will then be used to identify areas in which additional research is needed if harmonization of the two standards is to occur.
Evaluation of standards for transmission loss tests
Authors: Cassidy Matthew , Cooper Richard K. , Gault Richard , Wang Jian
Published: May 2008

FG Wilson, a generator set manufacturer in Larne, UK, (part of the CAT Electric Power Division), has an acoustics facility for obtaining noise emission of current products, future developments and research. A wall between a hemi-anechoic chamber and a reverberation room contains an aperture which is used for testing canopy panels to determine their sound transmission loss. Two different standard procedures for transmission loss testing are compared; the J1400, and ISO 15186. Tests were carried out on both to determine which is most feasible for the company to use. The J1400 is a variation of the ASTM E90 which uses the same method but is specifically for a reverberation room to hemi-anechoic chamber. A known 'limp' material, chosen to be lead, is used to obtain a transmission loss correction. ISO 15186 is based on a sound intensity method. A microphone on the source side recorded the sound pressure levels, and an intensity mapping was done on the receiving side, from which transmission loss was calculated. Two tests were completed; a lead sheet, and a steel plate. Both standards showed an acceptable accuracy in relation to the mass law.
Evaluation of Metrics for Field Airborne Sound Isolation
Authors: Dong Wayland , Loverde John
Published: May 2008

ASTM E336 and ISO 140 define several metrics describing airborne sound isolation for field measurements of wall and floor/ceiling assemblies. The current standards include provisions for the measurements of an apparent sound power reduction (ASTC and R'w), a non-normalized noise reduction (NIC and Dn,w), and a normalized noise reduction (NNIC and DnT,w). In a previous paper [LoVerde and Dong, J. Acoust. Soc. Am. 119, 3219 (2006)], the relationships between these metrics were reviewed. The desired metric for isolation in residential uses is discussed, specifically whether it should be based on sound power and related to the performance of the partition system (ASTC and R'w), or based on sound pressure and related to the acoustic isolation between spaces (NNIC or NIC or ISO equivalents). The analysis indicates that the sound pressure-based metric is preferred. Since power and pressure-based airborne sound metrics have small differences in field tested assemblies in most cases, it appears engineers have assumed that ASTC (and R'w) correlates with isolation. Field tests where this assumption does not hold are presented. In these cases, the power metric provides an inaccurate assessment of the acoustic isolation and can lead to engineering evaluations inconsistent with actual performance.
Sound-focusing effects in the plan of horse-shoe shaped opera theatres
Authors: Iannace Gino , Ianniello Elvira
Published: May 2008

An acoustical feature reported specifically for Italian-style opera houses is the non uniformity of early sound in the stalls. The curvature of the lower part of the lateral walls produces a sort of partial wave-guiding effect, like the well known "whispering gallery" effect, that is responsible of the concentration of early sound energy at seats located back in the stalls when the sound source radiates from the foreground of the stage floor. As much of the global room impression depends on the early part of the impulse response it can be supposed that the perceived sound quality of singers' voice and instrumentalists' music performing on the stage will be much different if the listener seats in the last rows with respect to different locations in the stalls. This paper reports an objective analysis on this subject based on measurements carried out in the stalls of a baroque-type theatre. Relevant computer simulations were also implemented.
Opera Performance in a Broadway Roadhouse
Authors: Schuette Dawn
Published: May 2008

The John A. Williams Theatre at The Cobb Energy Centre for the Performing Arts is a facility that was designed to accommodate touring, large-scale musical theatre productions, such as presentations of off-Broadway shows, as its primary revenue source. The 2750-seat space has recently received rave reviews, not just for its amplified music capabilities but for non-amplified opera presented by the Atlanta Opera, the first resident company in the facility. This paper discusses how the room form as well as fixed and adjustable acoustic elements in the space have allowed it to be successful for its various uses being conscious of its construction budget limitations. [Work completed while author was employed as a Principal Consultant at Kirkegaard Associates.]
Acoustics of a selection of famous 18th century opera houses: Versailles, Markgräfliches, Drottningholm, Schweitzingen
Authors: Bassuet Alban A.
Published: May 2008

This paper presents the analysis of the acoustical measurements conducted in 8 renowned baroque Opera Houses located in France and Germany. Still in authentic condition to their time of usage, and incorporating the historical changing scenery system (shutter and groove), these Houses have undergone little renovations. The acoustical analysis investigates the performances of these great Houses using energy parameters, balance between stage and orchestra parameters, 3D intensity plots, new spatial distribution parameters and timbre frequency analysis. The objective of the study is to deduce (for the Constellation Project) design targets for a medium size Opera House against these benchmarks and also to revisit the use of the lateral changing scenery system as used in the Baroque era, as an original scenery design concept for a new House. The paper presents the unique qualities of the rooms, illustrates some of acoustical benefits of the 18th century Opera House design characteristics, discusses some differences in the design approach between the Italian and the French traditions and proposes new perspectives for modern Opera Houses design.
Relating the hospital sound environment to occupant psychological and physiological response
Authors: Persson Waye Kerstin , Ryherd Erica , Lindahl Berit , Bergbom Ingegerd
Published: May 2008

Examining the relationship between specific acoustical characteristics of noise and occupant response is a fundamental step in determining the current hospital soundscape. Hospitals should be conducive to patient recovery and safety as well as employee health and productivity. Therefore, the sound environment that occupants are exposed to should be attended to from a health standpoint. Previous research on hospital patients has indicated negative effects of hospital sounds such as sleep disturbance, cardiovascular response, increased incidence of rehospitalization, extended hospital stay, and increased dosages of pain medication. There is some evidence that overall levels of hospital noise may impact staff mental efficiency, short-term memory and stress. A series of studies are currently being conducted by the authors to evaluate the modern hospital soundscape and the associated psycho-physiological responses of occupants, incorporating both quantitative and qualitative approaches. One phase in which detailed sound measurements, staff evaluations, and patient physiological measurements were conducted in a general intensive care unit will be highlighted, focusing also on methodological aspects related to physiological measurements. This phase also includes evaluation of patient ICU delirium, a condition that may negatively impact patient health and length of stay in the hospital. [Work supported by ASA and Swedish FAS].
Acoustics in the Environment of Care: An Interdisciplinary Harvard Medical School Research Project
Authors: Solet Joanne , Carballeira Andrew , Buxton Orfeu , Wyshak Grace
Published: May 2008

Noise in hospitals and healthcare facilities is a growing concern. Anticipating the wave of aging baby-boomers, the US healthcare industry is committed to significant construction and renovation over the next decade. New construction guidelines from the American Institute of Architects/Facility Guidelines Institute and the LEED-based "Green Guide for Healthcare" recognize improved acoustical conditions as vital to quality of care quality. To set these specific standards for acoustical performance in healthcare facilities, clinical evidence is needed on the impact of the acoustical environment on patients. An interdisciplinary team of Harvard Medical School faculty and acoustical engineers, in concert with public policy professionals, have designed and implemented a simulation methodology to test acoustic disruption of sleep in human subjects. This research collaboration uses soundscapes derived from recordings made in real healthcare environments, and then quantifies the human response to them. The methodology also enables virtual design changes with corresponding subject exposure to acoustically improved environments. Studies of the human sleep response using this methodology are providing objective evidence for establishing and validating design and construction standards to integrate improved acoustics with healthcare facility design.
Speech privacy in healthcare buildings:review of early studies and current procedures for analysis
Authors: Cavanaugh William J. , Tocci Gregory C.
Published: May 2008

Studies on speech privacy problems in buildings, including healthcare facilities, since the mid-1950s, have convincingly shown that a person's sense of acoustical privacy is directly related to the intelligability of the intruding speech in adjacent spaces [Cavanaugh et al, "Speech Privacy in Buildings" J. Acoust. Soc. Am. 34, 475-492 (1962)]. Both in laboratory and in real-world settings people feel they have adequate "confidential" privacy when the articulation index (AI) of the intruding speech is 0.05 or less. Higher values of AI, up to about 0.15, are acceptable for less demanding tasks, i.e. "normal" or "everyday" privacy. The analysis procedure quantifies each of the significant variables involved and compares summations of these metrics with response data from prior case histories both to predict and, in the case of existing situations, to evaluate speech privacy conditions. In the mid-1960s independent review of the analysis method showed that sufficient accuracy is preserved if A-scale metrics are used in place ofmore cumbersome frequency-based metrics. later in the 1960s the method was successfully applied to open plan spaces although achieving confidential levels of speech privacy in such spaces proved difficult. Lessons leared in applying this relatively simple analysis method over the years are discussed.
New Measurement Procedure and Rating Categories for Speech Privacy of Closed Rooms
Authors: Bradley John S. , Gover Brad N.
Published: May 2008

A procedure for assessing the speech privacy of enclosed rooms is described based on measured level differences between room-average levels in the room and levels at spot receivers 0.25 m from the outside boundaries of the room. The procedure is not sensitive to the acoustics of the receiving space, assesses conditions at more sensitive listening positions, and can describe variations in speech privacy due to weaker elements such as doors. The arithmetic average of the level differences over speech frequencies from 160 to 5k Hz is used to determine uniform-weighted signal-to-noise ratios found to indicate the audibility and intelligibility of transmitted speech (J. Acoust. Soc. Am. 116 (6) 3480-3490 (2004)). The degree of speech privacy is related to the speech levels in the room, the measured transmission characteristics and ambient noise levels outside the room. The probability of transmitted speech being audible or intelligible to eavesdroppers is related to the likelihood of louder speech in the meeting room. The measured statistics of speech levels in a large number of meeting rooms have been used to describe categories of speech privacy of rooms ranging from minimal privacy to situations where transmitted speech would be very rarely audible.
Acoustic Design for Open Plan Spaces
Authors: Hellström Björn , Nilsson Erling , Berthelsen Björn
Published: May 2008

In an ongoing Nordic cooperation project (Nordic Innovation Center - Sound Design of Open-Plan Offices) the acoustical conditions in open-plan spaces are investigated (see also the adjacent paper Room Acoustical Measures for Open Plan Spaces). The project's starting point is that acoustic qualities in terms of communication, orientation, comfort and privacy are crucial for open-plan spaces. Therefore, beside acoustic parameters, the aim is to develop methodologies in order to measure and specify such qualities. Beside site analyses, one major methodological tool concerns the development of a questionnaire, intended to be utilized as a compliment to acoustic measurements, and thereby function as a tool for design measures of large open-plan offices. Its purpose is to aid acousticians as well as architects and designers to identify different types of acoustic design criteria. The questionnaire covers not only the perception of the sound environment, but also psychosocial criteria, architectural design and the furnishing of the workplace. These qualitative criteria will be discussed and suitable parameters for design and evaluation of open-plan spaces will be suggested.
Adaptive sound masking
Authors: Chanaud Robert , Zuydervliet Ronald
Published: May 2008

Because activity sound levels vary widely during the day in open offices, fixed level sound masking spectra do not keep employees free of distractions. Programmed level control, time scheduling that permits hourly changes in level, is considerably better, but requires pre-knowledge of the activity. An adaptive masking system detects and responds to activity sound, both human and nonhuman, to provide constancy of privacy as opposed to constancy of masking level. These systems use several sound detectors in an area, average the sound level from them, and develop a running table of percentile levels with a given sensitivity. Two percentile levels (L10 and L99) are used to separate the masking from the activity sound. The system acts to continually keep the difference between them constant. The advantage of adaptive masking will be shown by comparison with other methods. The distraction potential will be discussed in terms of dB-minutes. The overall design of these systems will be discussed and examples of experience with existing systems will be given.
Acoustics of new and renovated Russian opera houses: Decade 1998-2007
Authors: Lannie Michael
Published: May 2008

Four new opera houses have been built in Russia and two existing opera houses have been fully renovated during the last 10 years. New chairs were installed and new materials were used on the inner surfaces of the renovated theatres. All the opera houses are not very large and the biggest one has 1200 seats. The plan of the two theatres has a horse-shoe form that is typical for old classic opera houses. The other three theatres have plans which are close to rectangular and one renovated theatre has a semicircular form of the back walls behind the stalls and the large balcony. The subject of the presentation is the acoustic design of these theatres. The results of the acoustic measurements which have been done in the halls are going to be discussed as well. Acoustics of the recently opened fully renovated Moscow academic musical theatre for 1100 seats is going to be presented in a more substantial way.
CARMEN® in the Norwich Theatre Royal, UK
Authors: Rougier Christophe , Schmich Isabelle , Chervin Paul , Gillieron Paul
Published: May 2008

Since 1999 the CARMEN® system has been installed in several halls in Europe. The last installation took place in November 2007 at the Norwich Theatre Royal. This classical stage venue has been completely refurbished to become a multipurpose hall with 1280 seats and a single very deep balcony. To fulfil the different acoustic requirements for each performance type (from speech drama to symphonic music) it was decided to install an electroacoustic Reverberation Enhancement System. CARMEN® is a regenerative one which is based upon the virtual wall principle. It can increase the Reverberation Time (RT) of a hall up to 100% and adapt the acoustics to each performance. The installed system has been tuned with 6 configurations: Theatre, Chamber Music, Opera, Concerto, Symphony, and Chorus. The RT of the empty hall now ranges from 1.1s without CARMEN® to 2.2s in the Chorus preset. A brief description of the CARMEN® principle will be presented first. Then the tuning of the different configurations in the hall will be described. Empty hall measurements have been done and the measured acoustic criteria will be analysed. The deep balcony of the Norwich Theatre Royal separates it into two slightly coupled volumes. This particularity will be discussed.
Singers' preferences for acoustical characteristics of concert halls
Authors: Stetson Kathleen , Braasch Jonas
Published: May 2008

It is the goal of acousticians aiding in concert hall design to create an ideal acoustical environment for experiencing music. To this end, parameters have been developed to quantify the listener's experience in a hall, and while many contribute positively toward listener satisfaction, they only tell part of the story. In reality, the experience of a listener is dependent on the quality of the performance occurring in the hall in addition to the acoustics; even great performers can only perform their best when in comfortable environments conducive to their art. Yet only one widely used parameter, Stage Support, considers a performer's acoustical needs, and this metric only applies to instrumentalists playing in ensemble. This study examines the unexplored case of a solo singer in a concert hall, augmenting the little existing research on this subject as a first step toward a new parameter. Subjective responses from a survey given to a number of experienced singers and the preferences of singers for acoustical aspects of various virtual concert halls, auralized real-time as the singers sang, are examined. The limitations in using typical acoustical measurement techniques to capture data for voice self-perception are discussed.
Diffuser design for both auditorium and stage acoustics in concert halls
Authors: Kim Jae Ho , Kim Yong Hee , Jeon Jin Yong
Published: May 2008

This study investigates the effect of the shapes and the locations of diffusers on acoustical characteristics, both in the audience area and on the stage, using a 1:50 scale model. Random-incidence scattering coefficients of the diffusers were measured in a reverberation chamber together with the RT, EDT, C80, G and ST1 of the model hall. The results show that an appropriate design of diffusers in halls affects the sound field of both the auditorium and the stage of the hall. It was also found that the effective number of surface reflections at a receiver position actually quantifies the sound diffusion. Through instillation of omni-directional diffusers close to stage walls, the number of reflected rays increases not only in the audience area but also in the stage area.
New (stage) parameter for conductor's acoustics
Authors: Van Den Braak Elisabeth W. , Van Luxemburg Laurentius C.
Published: May 2008

During fine-tuning of the stage acoustics of the main auditorium of Casa da Musica, designed by the Office for Metropolitan Architecture, in Porto (Portugal) we were confronted with conflicting comments with respect to the acoustic effect of different canopy positions. The well known stage parameters, ST and CS, did not point out a difference in results for the different canopy positions, while the conductor's experience did. So we carried out several measurements and tried to find a parameter that could clarify the contradictory experiences of the musicians and the conductor. We needed a parameter that correlated with the 'transversely support over the stage' instead of or additional to the known parameters. It was also not clear to what degree the commonly used parameters describe the acoustics at the conductor's position. This study aims at proposing a new (stage) parameter as well as trying to find out more about the 'conductor's acoustics'. In the main auditorium (CdM) the newly defined parameter seems to describe the musicians' and conductor's experiences on the hearing 'ensemble' on stage even better than the known stage parameters. The same measurements have been carried out in other halls in order to check the validity of this new parameter.
On the interaction between double basses and the stage floor
Authors: Guettler Knut , Askenfelt Anders , Buen Anders
Published: May 2008

Double bassists unanimously claim the importance of a compliant stage floor for producing a warm and nuanced orchestra sound. However, in the limited number of reports studying the stage floor's contribution to radiated sound no clear conclusion has been reached. The present study, based on measurements of three concert halls and three double basses, points at some measurable features that should be considered when trying to settle the question: (1) With a compliant floor the velocity transfer between the bass bridge and floor is often higher than 0 dB in the low-frequency range. In these cases the bass largely acts as a mass (viewed from the end pin) while the floor acts like a spring. (2) The floor properties affect the bridge mobility in the low-frequency range. (3) Below the Helmholtz resonance, around 60 Hz, the radiation of the bass corpus falls about 40 dB within one octave while the ratio between the input power at the bridge and the power transferred to the floor via the end pin has been observed to boost from 3 to 40% in the same range. (4) The effect of a compliant floor may be more pronounced for the player than for the audience.
Designing a desirable medium-sized multipurpose hall using ODEON
Authors: Duty Jason , Savitala Hari V.
Published: May 2008

This presentation focuses on using the room acoustics program ODEON for modeling a desirable medium-sized multipurpose hall (400-600 seats). A sampling of medium-sized halls was taken and impulse response measurements were conducted with drapes deployed and retracted. In each hall, the same configurations were modeled in ODEON. Acoustical parameters, such as T20, T30, C50, C80, were used to check the agreement of the model to the measurements. A systematic approach was then used to adjust model parameters to match the real-world measurements. These results and modifications are presented to better understand how to accurately model and design medium-sized multipurpose halls.
The acoustical design of rehearsal rooms for orchestra and choir in the Teatro Lirico in Cagliari
Authors: Farnetani Andrea , Prodi Nicola , Pompoli Roberto
Published: May 2008

The acoustical conditions of rehearsal rooms are of primal importance during the training process of an orchestra or a choir. For this reason these spaces should be specifically designed to allow the musicians to clearly ear themselves and each other. At the same time an appropriate sound level should be maintained to avoid extensive exposure to high levels, which is a risk seldom lamented among musicians. Notwithstanding the peculiar role of these rooms in the musical production process, their acoustical requirements are still not sufficiently clarified. In particular the most effective parameters to employ and the best ranges to adopt need further investigations. This work reports the final acoustical optimization of the orchestra and choir rehearsal rooms in the Teatro Lirico in Cagliari (Italy). The comparison between the acoustical parameters before and after the refurbishment will be shown and discussed, with a focus on the difference between the sound level generated by the performer himself and by the others.
Establishment a methodology for an objective-subjective acoustic analysis in a multifunctional hall: Paraninfo of the Polytechnic University of Valencia
Authors: Lacatis Radu , Giménez Alicia , Cerdá Salvador , Cibrián Rosa , Romero José , Barba Sevillano Arturo
Published: May 2008

This study presents a methodology for the acoustic analysis, from a comprehensive study of a multifunctional hall, of the Polytechnic University of Valencia, as a pilot hall in a Spanish Coordinated Project. The acoustic parameters studied were those who the most acoustics experts consider of interest. In the objective measures were use the equipment and methods conforming to ISO 3382. The questionnaire used to analyze the subjective response has been patented in Spain, by the research group that developed the project. The correlation between objective and subjective results, along with the accurate simulation of the hall provides a valid tool for design, restoration and improvements the enclosures where the sound quality is preferred.
Relationship between room shape and acoustics of rectangular concert halls
Authors: Klosak Andrzej K. , Gade Anders C.
Published: May 2008

Extensive acoustics computer simulations have been made using Odeon computer simulation software. In 24 rectangular rooms representing "shoe-box" type concert halls with volumes of 8 000 m3, 12 000 m3 and 16 000 m3 from 300 to 850 measurements positions have been analysed. Only room averaged objective measures are considered here, in particular Clarity (C80), Strength (G) and Early Lateral Energy Fraction (LF80). Results from simulations have been compared with regression models created based on real hall measurements. In general, simulated results of C80 and G are found to be in good agreement with regression models. Divergences are found in LF80 behaviour; these have been associated with influence of proportions of rectangular halls. Updated formula for predicting of LF80 in rectangular halls has been proposed, which takes into the account both width and length of hall.
Signal analysis in the sound absorption measurement procedure: The importance of time subtraction and reference surface corrections
Authors: Guidorzi Paolo , Garai Massimo
Published: May 2008

The sound absorption coefficient measurement (following ISO 13472-1 normative) of highly absorbing materials, which are tipically employed in room acoustic correction, presents some inherent difficulties. These materials present highly sound absorption coefficient indeed, but usually low sound insulation index and are installed over highly reflective surfaces. This leads to some measurement problems, partially solved by means of the reference surface method. In this work some measurement examples on the same materials but with different contour conditions are analyzed and the improvements on the results, due to reference surface normalization and time domain subtraction of free field response, are discussed.
Directivity control with Wave Field Synthesis: implications for live music performances
Authors: Caulkins Terence , Corteel Etienne , Sanson Joseph , Warusfel Olivier
Published: May 2008

Loudspeaker room interaction has a large impact on the perception of surround sound, especially in the context of "mixed concert", in which a loudspeaker system is used to synthesize virtual instruments that share the acoustic space of the stage with real musicians. Loudspeakers excite the listening environment in a way that differs from real instruments since, by design, they tend to exhibit constant directivity characteristics as a function of frequency. Moreover, real instruments exhibit radiation patterns that vary according to pitch, fingering and expressive movements. We present an approach based on Wave Field Synthesis which enables a control of radiation properties of the loudspeaker system which can be dynamically monitored in real time. Applications and potential perceptual impacts are discussed, focusing on the possibility of using directivity control to vary the excitation of the concert hall in order to monitor early reflections level and direct/reverberant energy ratio associated to virtual sources.
Acoustic Radiation Properties of Dynamic Loudspeaker Arrays versus Multiactuator Panels for Wave Field Synthesis
Authors: Pueo Basilio , Lopez José J.
Published: May 2008

Wave Field Synthesis (WFS) is a spatial sound rendering technique that generates a true sound field using loudspeaker arrays. Dynamic loudspeaker arrays, that were used since the beginning of WFS, is the technology employed in most prototypes. Alternatively, Distributed Mode Loudspeakers can be used to build arrays for WFS, also known as Multiactuator Panels (MAPs). For that purpose, multiple vibrating exciters are attached to a single flat panel of a light and stiff material, creating bending waves that are then radiated as sound fields. An analysis of the radiation properties and spatial performance of such loudspeaker arrays for WFS reproduction is presented in this paper. Wave fields have been interpreted in the wavenumber domain, where the source radiation is decomposed into plane waves for arbitrary angles of incidence. Then, measurement and analysis of the radiation performance, evaluation of the spatial aliasing frequency and associated sampling artefacts for both linear loudspeaker arrays are addressed. In addition, parameters that can modify spatial aliasing artifacts, such as truncation effects caused by the array geometry or array directivity are also discussed. Simulations and experiment results are discussed through several case studies, comparing dynamic loudspeaker arrays and MAPs in WFS operation.
Effects of practical loudspeaker characteristics on virtual acoustic imaging systems
Authors: Qiu Xiaojun , Vorlaender Michael
Published: May 2008

Loudspeakers used in virtual acoustic imaging systems are usually considered as monopoles in the models; however, it is only an approximation at low frequency range, and practical loudspeaker boxes behave complex directivity in mid to high frequency range and almost only radiate in the front direction above a certain frequency. Some studies have taken into account of the frequency response characteristics of the loudspeakers in virtual acoustic imaging systems, and others have considered their directivity characteristics separately. This paper presents a complete model of a virtual acoustics imaging system which takes account of both the temporal and spatial characteristics of the sound sources, and the effects of practical loudspeaker characteristics on virtual acoustic imaging systems are studied.
High Environmental Quality (HQE), the GIAc/ADEME approach
Authors: Gaucher Eric
Published: May 2008

The "Haute Qualité Environnementale" HQE concept is increasingly important for French building. The French acoustics consultants association, GIAc, has been working, with the ADEME's support in order to define acoustically a building that aims to be HQE. The approach is to come back to the analysis of a building acoustics situation: the activity developed in a room generates a sound which can disturb activities held in surrounding rooms. In return, this very activity requires quietness to be held in adequate conditions. If we define rules allowing quantification of this aggressivity and sensitivity, we can deduce the insulation criteria corresponding to the quality we are looking for. The main advantage of this method is the homogeneity it induces on the different criteria, which were usually defined independently one from the other. Many present situations show that the equilibrium between acoustic criteria is at least as important as their absolute values. Even though this approach has not been included in the QEB reference book, it can be used to validate the absolute values, to extend the qualification to other kinds of rooms, and also to adapt objective criteria to different situations.
Auditory sketching as a tool in architectural design education
Authors: Frank Tim , Okcu Selen
Published: May 2008

Architectural spaces are perceived through embodied experiences that are made up of both visual and non-visual stimuli. However, the conventional means that a designer uses to depict non -visual stimuli such as aural phenomena contain a visual bias. We have introduced a new aural drawing system called, "Auditory Sketching" as a way for design students to visualize the auditory fields that structure one's perception of architectural space. The Auditory Sketching procedure requires that the design student first mediate aural perceptions linguistically through meticulous observation during which they are encouraged to define aural qualities within the space such as notes, tones, clusters, bands, and pitches that would be difficult to capture using a graphic system of notation. Using this written language as a guide for graphic expression, they explore different ways of expressing these time and space notations with ink pens; creating an auditory system of 'tones' by building up marks in different ways: hatching, layering up, scribbling, etc. The eventual translation of aural perception into graphic patterns is crucial because designers need to visualize the sound in order to consider it a significant medium of architecture that they can define and shape.
Concepts & Methods in Architectural Acoustics from the Classical Period to the Enlightenment
Authors: Di Angelo Adam , Calamia Paul
Published: May 2008

Herein is presented a critical examination of the early concepts in architectural acoustics in the western world. This study suggests that the historical extent of architectural acoustics is much more sophisticated than is generally considered. The presentation focuses on specific contributors and their discoveries in the nascent art of architectural acoustics. Among those studied are Marcus Vitruvius Pollio, the ancient Roman architect responsible for the tome De Architectura; German polymath Athanasius Kircher who delicately balanced empirical science with magic to explain acoustical phenomena in his two books, the Phornugia Nova and the encyclopedic Musurgia Universalis; and English architects-cum-scientists Sir Samuel Morland and Sir Robert Hooke whose wide and varied research often entered into acoustics. In the works of these gentlemen are elegant, precocious, and sometimes absurd revelations on the science of sound and surface.
Acoustic characterization of rehabilitated cloisters
Authors: Carvalho Antonio P. , Vilela Silvia R.
Published: May 2008

This paper presents the results of field measurements in eight rehabilitated cloisters of old monasteries in Portugal (length: 20 to 35 m and height: 3.3 to 6.3 m) regarding their acoustic behavior to two objective parameters: RT and RASTI. The goal is to characterize the acoustic effect of the rehabilitation done on theses spaces to adapt them to new uses. All these cloisters had recently their galleries' openings to the central yard closed with glass panels. Simple formulas were obtained that relate among the objective acoustic parameters and between the acoustic and architectural parameters. This paper also presents the variation on the RASTI and RT average values resulting of the rehabilitation work done on these buildings.
Simulating bat sonar using vector sound intensity
Authors: Hickling Robert
Published: May 2008

In general bats use ultrasound to determine their surroundings and to detect flying insects. Generally the beam width of ultrasonic signals emitted by bats is too wide to distinguish closely-spaced objects and the receiving pattern of bats' ears is similar (J. A. Simmons, "Directionality of biosonar broadcasts and reception by the ears", Tutorial Lecture, ASA Spring Meeting, 2002). To locate an object requires knowing both distance and direction. Distance can be readily determined using time-of-flight. How a bat determines direction is less clear. In this presentation, an ultrasonic device is demonstrated that measures both distance and direction (R. Hickling, "Method and Apparatus for Echolocation" US Patent No. 7,054,226, May 2006). This uses a combination of a pulsed ultrasonic source and a vector sound-intensity probe. The probe has four ultrasonic receivers at the vertices of a regular tetrahedron and determines direction from the sound-intensity vector, using finite-difference approximations and the cross-spectral formulation. The frequencies of the echoes received by the probe have to be heterodyned down to lower frequencies for accuracy in the finite-difference approximations. Echolocation data using the device are presented.
Acoustic focussing: how flying bats control spatial distribution of Doppler-ranging errors by signal sweep rate
Authors: Holderied Marc W.
Published: May 2008

Echolocating bats obtain three-dimensional images of their surroundings in complete darkness by emitting sonar signals and evaluating returning echoes. When flying close to objects, bats risk collision and therefore depend on the accuracy of images - particularly in the perceived distance of obstacles, which is coded by the time delay between call and echo. Yet, during flight, such accuracy is perturbed first because bats call and receive echoes at different positions and second because echoes are modified by Doppler shifts. The spatial distribution of such ranging errors is range dependent - objects at one particular distance from the bat have zero ranging errors, while ranging-errors increase for closer or more distant objects. Interestingly, this distance of zero ranging error depends on signal design, in particular sweep rate. By adjusting signal design flying bats could shift this distance adaptively to their target of interested. Because this has similarities with focusing (i.e. accommodation) in vision, this distance is called distance of focus (DOF). We will present examples for actual distances of focus of different bat species in different behavioural contexts, such as search flight, obstacle avoidance and target approach. DOF gives a novel perspective to the adaptive relevance of frequency modulated sonar signals.
An acoustic finite-element model to study sonar interactions with marine mammals
Authors: Feijoo Gonzalo R. , Foote Kenneth G.
Published: May 2008

A computer model based on the finite-element method (FEM) is being developed to study the interaction of sonar signals with marine mammals. This model solves the Helmholtz equation in a computational box that includes the animal and the surrounding medium, water. The FEM code has been validated with analytical solutions for scattering of a plane wave by a fluid sphere over a range of parameters and frequencies of interest. The same FEM code has been applied to a 142-cm-long specimen of the common dolphin (Delphinus delphis); internal pressure and displacement fields have been computed. The animal is represented in the computer model by a set of tissue groups whose acoustic properties, density and sound speed, are taken from the literature. The geometry of each tissue group was constructed from segmented computerized tomography images. Results are presented for harmonic signals in the 1-10 kHz frequency range. [Work supported by NOPP through ONR award N000140710992.]
Simultaneous acoustic observations of turbulence and zooplankton
Authors: Ross Tetjana , Gaboury Isabelle , Lueck Rolf
Published: May 2008

Models and laboratory experiments show that zooplankton may locate food more easily in turbulent waters, but whether plankton seek or avoid turbulence in the ocean is an open question. It is difficult to measure turbulence and plankton simultaneously and with the necessary spatial resolution using traditional methods (nets and airfoil shear sensors). Acoustics is commonly used to survey zooplankton abundance and recent studies have shown that stratified turbulence can also be a significant source of sound scatter. This may seem like more of a complication than a boon for those aiming to use acoustics to observe plankton in turbulence. We present acoustic data, however, that show that at least under certain circumstances, zooplankton and turbulence can be observed simultaneously with a single 307 kHz sounder. The different natures of the two targets (discrete targets versus a volume effect) allow them to be distinguished. The key is sampling the same targets at multiple ranges and having low enough concentrations that there is no more than one animal within the beam at the closest ranges.
Estimation of macrophytes using single-beam and multibeam echosounding for environmental monitoring of arctic fjords (Kongsfjord, West Svalbard Island)
Authors: Kruss Aleksandra , Blondel Philippe , Tegowski Jaroslaw , Wiktor Jozef , Tatarek Agnieszka
Published: May 2008

This paper presents results of a study on the spatial distribution and biomass of macrophytobentos in a fjord of Arctic Svalbard. Kongsfjord represents a periglacial environment with intense morphodynamic processes and rapidly progressing changes in the biotic environment, making it one of the most promising areas to research climate impact on ecosystems. The main objective was to provide an acoustic tool for the evaluation of benthic habitats. The 2007 field survey included systematic, co-registered, single-beam and multibeam echosounder measurements. Acoustic observations were verified by biological samplings and observations for the classification algorithm development and verification. Analyses of acoustic signals scattered on bottoms covered by algae indicate the good quality of the data recorded, providing a map of phytobenthos distribution and biomass estimation in Kongsfjord. The algorithms designed and tested for processing single- and multibeam data allow extracting the morphological forms of the bottom and determine the areas covered by algae. This survey was the first instance where a multibeam imager was used to map macrophytes in an Arctic environment, in a wide variety of depths and ranges. Comparing the two types of echosounders was a great opportunity to understand the visualisation of macrophytes by multibeam systems and their identification.
Acoustic properties of multifunctional nano/microbubbles used in ultrasonography and ultrasound-mediated chemotherapy
Authors: Rapoport Natalia , Nam Kwon-Ho , Gao Zhonggao , Cristensen Douglas A. , Kennedy Anne M.
Published: May 2008

Multifunctional nano/microbubbles were developed that combine properties of drug carriers, ultrasound imaging contrast agents, and enhancers of ultrasound-mediated drug delivery. At room temperature, the formulations comprised perfluoropentane (PFP) nanodroplets stabilized by biodegradable diblock copolymers. The nanodroplets converted into nano/microbubbles upon heating or ultrasound irradiation. The acoustic properties of the droplets and corresponding bubbles depended on the type of the bubble stabilizing copolymer. Two different copolymers were tested, poly(ethylene oxide)-co-poly(L-lactide) (PEG-PLLA) and poly(ethylene oxide)-co-polycaprolactone (PEG-PCL). For the same quantitative composition, the PEG-PLLA-stabilized bubbles demonstrated higher inertial cavitation threshold and coalescence propensity than PEG-PCL-stabilized bubbles. Nanobubble tendency to coalescence is advantageous for using PEG-PLLA bubbles as tumor-targeted contrast agents.On the other hand, a lower cavitation threshold for PEG-PCL-stabilized bubbles is useful for ultrasound-mediated drug delivery. The drug doxorubicin (DOX) was localized in the bubble walls; it was released from the bubbles in response to sonication by therapeutic ultrasound, which resulted in a significant degree of drug tumor-targeting and effective tumor chemotherapy.