bluuebunny/crossref_metadata_2025 huggingface dataset:
Online adaptive distributed control of vibro-acoustic systems
Authors: Frampton Kenneth
Published: May 2008

One of the primary difficulties in distributed, real-time vibro-acoustic control is the difficulty of high-bandwidth network communication of sensor data. The necessary communications rate has proven overwhelming to existing communications protocols. In order to overcome this limitations an adaptive control technique has been developed that requires only occasional inter-node communication of sensor data in order to maintain optimal performance. The technique is based on iterative feedback tuning (IFT) which has the advantage of not requiring a system model. In this system, each control node collects its sensor data over a period of time. The data is then communicated to other nodes in the system. Once a node has received the required sensor data the local adaptation algorithm is initiated. Local feedback gains are adjusted based on an estimate of the cost function gradient and the new control law is implemented until the next adaptation cycle. This work presents the theory behind this adaptive control technique and simulation results of the control performance are presented. It is demonstrated that this approach to distributed control can perform as well as model based optimal distributed control, and nearly as well as centralized control.
Hybrid Foams for passive/active control of transmission loss of panels
Authors: Ouisse Morvan , Collet Manuel
Published: May 2008

Absorbing materials are widely used in transport industry. Classical foams can efficiently improve transmission loss of panels, but only in the higher frequency range. For the lower part of the frequency range, structural active control can be a good strategy to reduce the vibratory level and induced noise. Trying to take advantage of those two points is the objective of the development of hybrid foams. Many practical and scientific aspects are related to their design: which passive material should be used? Which active material, and what shapes should be better? In order to understand the basics of the hybrid foams, some specific multiphysics models are developed, including vibro-acoustic modelling of foams, coupled with elasto-dynamics for structural parts and piezo-elastic models for active parts. The objective of the strategy is to try to take advantage of distributed actuators within the foam in order to modify the energy transmission path. The physical strategy is presented in the paper, together with the full description of the model, with numerical results. The main difficulty for the numerical part is the very high number of degrees of freedom which are required by the model. Some model reduction strategies are then investigated.
Implications of the fluctuating drag force voice source
Authors: McGowan Richard S. , Howe Michael S.
Published: May 2008

A recently published paper on the aeroacoustics of the voice source calculates the acoustic source of voice caused by fluctuation drag forces [Howe, M. S. and McGowan, R. S., J. Fluid Mech., 592, 367-92]. There are two extensions to this calculation that will be presented: 1) inclusion of the ventricular folds downstream of the vocal folds, and 2) the fluid-structure interaction at the vocal folds. For the ventricular folds, the effect of tissue shape on the drag forces will be investigated in terms of the shape's effect on the relation between the Lamb vector and the Kirchoff vector. Regarding the fluid-structure interaction at the vocal folds, the two-mass model will be examined in light of the recently published calculation of drag forces. [Work supported by grant NIDCD-004688 to Dr. G. S. Berke of UCLA.]
Aeroacoustic production of speech sounds
Authors: Krane Michael
Published: May 2008

Speech sound production is described in terms of its essential physics by focusing on the aeroacoustics of jets in the vocal tract. Aeroacoustic theory is used to show that the primary sources of sound may be expressed in terms of unsteady aerodynamic forces on the vocal tract walls, especially where a jet is formed, and where the jet performs a strong interaction with the walls. The theory further clarifies which details of jet structure and vocal tract geometry contribute to sound production. This information is used to guide useful approximations concerning the aerodynamics. With the assistance of measurement, these approximations are used to develop a model of the sound source in the time and frequency domains. The contribution of jet structure and vocal tract geometry to sound source characteristics is then discussed. Model predictions of the resulting acoustic field are compared to acoustic measurements.
Increasing the complexity of glottal flow models: in-vitro validation for steady flow conditions
Authors: Cisonni Julien , Van Hirtum Annemie , Luo Xiao Yu , Pelorson Xavier
Published: May 2008

Quasi one-dimensional glottal flow descriptions predict vocal folds oscillations characteristics which are qualitatively relevant to in-vitro and in-vivo experimental data. The current paper considers the resolution of the 2D Navier-Stokes equations in order to obtain a refined description of the flow phenomena adapted to more realistic glottal geometry. The pressure and flow rate predictions obtained from quasi one-dimensional flow models and the resolution of the 2D Navier-Stokes equations are examined for steady flows within a rigid glottis. The models predictions are validated against in-vitro measurements performed on rigid constriction replicas comparable to the geometrical conditions of the glottis and mounted in a suitable set-up. The confrontation between the experimental and computed data tends to show that the accuracy of the estimated pressures increases with the complexity of the flow model whereas the inverse tendency can be observed for the estimated flow rates. A focus is made on the flow separation point which is predicted by the resolution of the Navier-Stokes equations and appears to be a crucial parameter of the quasi one-dimensional flow models. The use of a variable separation criterion obtained from the 2D flow modelling in the quasi one-dimensional models makes the different models predictions more similar.
Aeroacoustic measurements in a vocal tract model
Authors: Leonard Daniel J. , Krane Michael
Published: May 2008

An experiment to clarify the relation between turbulent jet structure, vocal tract wall shape and the resulting sound is described. A life-scale model of the vocal tract (18cm length, 2.6cmx2.6cm square cross-section), fabricated from clear cast acrylic is used. A jet, formed at a constriction, passes over or against a simple obstacle, generating sound. Correlated aerodynamic and acoustic measurements are used to determine the transfer function between the obstacle and the measurement location outside the model and the aeroacoustic source spectrum. For comparison the source spectrum is also estimated using the model described in Krane (JASA, 2005), using aerodynamic measurements as empirical input.
Influence of vocal fold stiffness on phonation characteristics at onset in a body-cover vocal fold model
Authors: Zhang Zhaoyan , Neubauer Juergen
Published: May 2008

The influence of the body and cover stiffnesses on phonation onset and the resulting vibration pattern was investigated in a body-cover continuum model of the vocal folds. An eigenvalue analysis was performed to obtained phonation onset characteristics. The analysis showed that, with increasing body-cover stiffness ratio, both the phonation threshold pressure and frequency (normalized by the Young's modulus and wave speed of the cover layer, respectively) first increased rapidly and then gradually approached a plateau. For a given glottal resting opening, a soft vocal fold body led to a larger prephonatory glottal opening, which had an negative effect on phonation onset pressure, and for certain vocal fold geometries, led to a local minimum in the phonation threshold pressure as a function of the body stiffness. Although the phonation threshold pressure was low for a vocal fold configuration with both a soft cover and a soft body, the vocal fold vibration at onset exhibited a significant whole-body vertical motion and a low sound production efficiency, and therefore it may not be desirable for voice production. For a large body-cover stiffness ratio, this vertical motion was suppressed and vibration was restricted to the cover layer and the medial surface, resulting in a more effective flow modulation and a better sound production efficiency.
Modeling of voice registers and bifurcation theory
Authors: Zemke Marco , Tokuda Isao , Herzel Hanspeter
Published: May 2008

The exact definition of registers in the human voice is still under debate. Especially the quantitative analysis of transitions between these registers have not been investigated in much detail yet. Experiments show different kinds of voice instabilities that appear close to the transition from chest to falsetto register. These instabilities include abrupt jumps between the two registers exhibiting hysteresis, aphonic episodes, subharmonics and chaos. To model these phenomena we start with a three mass cover model of the human larynx which can vibrate in chest and falsetto like patterns. We extend our model to a four mass body-cover polygon model with a supraglottal resonator. We more realistic make use of bifurcation theory to understand how small smooth changes of parameter values can cause sudden qualitative changes in the dynamical behavior of the larynx. Experiments with excised human larynges and untrained singers show comparable coexistence of both registers in a extended parameter region. Our study suggests that voice range profiles can be generalized as two dimensional bifurcation diagrams.
Towards sibilant /s/ modelling: preliminary computational results
Authors: Grandchamp Xavier , Van Hirtum Annemie , Pelorson Xavier , Nozaki Kazunori , Shimojo Shinji
Published: May 2008

Acoustic effects of the turbulence in human sounds production is generally accepted in the case of fricatives. Nevertheless, this phenomenon is not taken into account in physical modelling of the speech production. Steady flow in a uniform two dimensional channel with a one side triangular obstacle has been simulated using Large Eddy Simulation for different Reynolds numbers. The used geometrical and flow characteristics are severe simplifications of the human articulators during the production of the sibilant /s/. The impact of different geometrical configurations of the downstream obstacle representing the teeth on the computational results is searched in order to detect the aeroacoustic sources produced by turbulent flow, crucial in /s/ production.
Involvement of Auditory Cortex in Speech Production
Authors: Guenther Frank H.
Published: May 2008

In addition to their role in speech perception, the auditory cortical areas of the superior temporal lobe are important for the formation and maintenance of motor commands for speech production. Using a combination of neural network modeling, neuroimaging, and auditory perturbation experiments, we have characterized the network of brain regions involved in auditory feedback control of segmental aspects of speech. This network involves auditory error cells in bilateral posterior superior temporal cortex which become active when the current auditory feedback mismatches the auditory target for the current speech sound. Projections from these auditory cortical areas to the right hemisphere ventral premotor areas, then on to primary motor cortex, transform perceived auditory errors into corrective movement commands for the speech articulators. The DIVA model of speech production produces a close quantitative fit to acoustic data collected during unexpected auditory perturbation of speech and during sensorimotor adaptation to sustained auditory perturbations. Neuroimaging results motivate a modification of the model to include right ventral premotor cortical areas in the auditory feedback circuit for speech production. [Work supported by NIDCD, NSF.]
Bayesian approach to signal detection, source localization and ocean environmental parameter estimation
Authors: Nolte Loren W.
Published: May 2008

From a Bayesian perspective, signal detection, source localization and ocean environmental parameter estimation algorithms can be viewed as simultaneous signal processing operation. In these cases, the likelihood function provides a mechanism for incorporating physical models of the ocean environment. In addition, one can incorporate uncertainties of source location and ocean environmental parameters a priori, rather than dealing with them "after the processing", and this approach also provides a posteriori probabilities of these source and ocean parameters as outputs of the processing. In addition to affecting the structure of optimal signal processing algorithms, these uncertainties affect how well one can spatially localize the source of sound, or the accuracy with which one can estimate the ocean environmental parameters. In passive and active sonar detection, these uncertainties, along with the knowledge of the ocean physics that has been incorporated in the likelihood function, determine detection performance. In particular, this paper will illustrate how signal detection theory can provide quantitative upper bounds of sonar detection performance on the receiver operating characteristic (ROC) as a function of the amount of uncertainty in ocean environmental parameters, source location, and signal-to-noise ratio.
Inference and learning in gamma chains for Bayesian audio processing
Authors: Cemgil Ali Taylan , Dikmen Onur
Published: May 2008

Statistical description of complex phenomena encountered in many applications requires construction of nonstationary models. A first step in analysis of such nonstationary sources involves typically a traditional time-frequency analysis Short time Fourier transform. In all these techniques, the underlying implicit assumption is that the process is piecewise stationarity, however dependencies across frequency bands or time frames are not explicitly characterised. Here, we investigate a class of prior models, called Gamma chains, for modelling such statistical dependencies in the time-frequency representations of signals. In particular, we model the prior variance of transform coefficients using Markov chains, trees and fields of inverse Gamma random variables. This model class is Markovian and conditionally conjugate, so standard inference methods like Gibbs sampling, variational Bayes or sequential Monte Carlo can be applied effectively and efficiently. We also show how hyperparameters, that determine the coupling between prior variances of transform coefficients, can also be optimised. We discuss the pros and cons of various inference schemata (variational Bayes, Gibss sampler and particle filtering) in terms of complexity and optimisation performance for this model class. We illustrate the effectiveness of our approach in audio denoising and single channel audio source separation applications.
New Numerical Computation of Acoustic Propagation in the Ocean in the Presence of Internal Waves is 1000 Times Faster than Traditional Split-Step Fourier Approaches
Authors: Osborne Alfred R.
Published: May 2008

A new numerical model for acoustic propagation based upon the large angle parabolic type equations is found to execute about 1000 times faster than the FFT split step algorithm. The approach is applied to the imaging and nonlinear filtering of internal waves in shallow water regions for 3-dimensional propagation of acoustic waves. For appropriate array placement one can construct the inverse problem and hence the internal wave field from the acoustic measurements themselves. The unique nonlinear filtering method allows one to filter out the internal waves from the density field and hence to realized acoustic wave propagation in the absence of the internal waves. The hyperfast acoustic model has some of the following characteristics: (1) The work can be extended to the fully 3-dimensional Helmholtz equation. (2) The method is a kind of multi-dimensional Fourier analysis which exactly solves the wave equations (PE, large angle PEs and Helmholtz)) so that the acoustic wave does not degrade with range as with more traditional numerical integrations. (4) Multi-dimensional Fourier transforms can be used to nonlinearly filter acoustic signals in a wide range of applications and hence the approach is quite robust to interference from background acoustic noise.
Phase change measurement, sound speed and attenuation determination from underwater acoustic panel tests
Authors: Piquette Jean , Paolero Anthony , Drake Robert
Published: May 2008

Material measurements in underwater acoustics are employed regularly for characterization of materials used as acoustic windows. Various techniques have been developed to measure the acoustic attenuation magnitudes of materials. Recently, there has been increased interest in window configurations of complex geometries and of phase response of that material to an acoustic wave. This latter phase parameter can be of high significance for acoustic devices composed of an array of elements. Thus, the phase response of the attenuation is needed to properly characterize material performance on the overall system. This translates into a primary need to measure the complex acoustic attenuation of panels at various angles of incidence. This paper summarizes the methodology to measure the complex attenuation of materials. Case examples of test materials measured will be presented; comparisons to theoretical response will be provided. Considerations given to rigging and required acoustic settling times are discussed. Expansion of the methodology that incorporates a causal relationship between the measured phase response and attenuation to the sound speed of the material will be developed. The model relating these parameters and their implementation via an iterative least squares fitting of the parameters to the measurement data will be discussed.
Panel transmission measurements: The influence of the non plane wave nature of the incident field
Authors: Humphrey Victor F. , Smith John
Published: May 2008

For reasons of cost and practicality, laboratory measurements of the acoustic transmission and reflection properties of materials for use in underwater applications are typically performed on samples of limited dimensions - and with the source and receiver separated by relatively short distances - resulting in a non planar measurement field. The influence of this on the resulting measurements is investigated in this paper. In particular, for low frequency measurements the influence of the evanescent wave contributions can become significant. In this paper two alternative approaches are used to evaluate the transmission properties. The first method decomposes the incident spherical wave into its plane wave components and integrates the resulting transmitted waves numerically to evaluate the transmitted field. The second approach uses an asymptotic expansion of the field in terms of wave front curvature: bounds are then placed on the error in this expansion at low frequency using thin plate theory. Results are compared and contrasted for measurements in the frequency range 1 to 60 kHz for panels of simple elastic materials (steel and Perspex (polymethylmethacrylate)). In addition the nature and significance of the modes of the panel for evanescent waves are considered. The consequences for laboratory measurements are also outlined.
Passive phase conjugation processing to forward scattering waves by target in shallow water
Authors: Tsurugaya Yoshiaki , Kikuchi Toshiaki , Mizutani Koichi
Published: May 2008

This paper describes the detection of an underwater target using a passive phase conjugation processing. It is assumed that a sound source and an array are disposed in shallow water, and a target exists between them. The traveling wave from the sound source and the scattered wave from the target are received by the array. However, they are received almost simultaneously. In addition, because the level of the traveling wave is considerably larger than that of the scattered wave, the detection of the scattered wave is difficult. Then, the traveling wave components are removed from the signals received in the array. And, the passive phase conjugation processing is given to the signals. The signal to which the passive phase conjugation is processed is similar with the signal radiated from the target. The signal radiated from the target relates to the sound wave that enters at the position of the target from the sound source for the small target. The sound wave that enters at the position of the target is uniquely decided depending on the condition of the propagation environment and the sound source. Therefore, the result that the passive phase conjugation is processed contains the position information of the target.
Detection and classification of a cylindrical target partially or completely buried in thin sand/water mixture by time-frequency representation
Authors: Maze Gerard , Decultot Dominique , Cacheleux Katia , Liétard Romain
Published: May 2008

Numerous papers show that it is possible to characterize an air-filled cylindrical shell immersed in water from a time-frequency representation. The time scattered signal is constituted by echoes related to the reradiation of waves circumnavigating around the cylindrical target. For particular frequencies, these echoes make resonances which characterize this target. In first part, the scattered signal is calculated, the cylindrical shell is in water or in a medium with characteristics similar to the mixture sand/water used for the experimental measurements. In second part, the cylindrical shell is partially or completely buried in a thin sand/water mixture. It is insonified in normal or oblique incidence relatively to the interface water/mixture. The impulse time scattered signal is plotted and it is treated with a time-frequency representation. The comparison between the theoretical and experimental time-frequency representations shows us that it is possible to detect and classify the object buried in thin sand/water mixture.
Acoustic radiation of low frequency flexural vibration modes in a submerged plate
Authors: Decultot Dominique , Liétard Romain , Chati Farid , Maze Gerard , Klauson Aleksander
Published: May 2008

In some submarine structures, the acoustic radiation of vibrations at the neighbourhood of sonar equipment limits their use. So the aim of this study is to understand the process of acoustic radiation of a submerged plate subjected to a vibration. For the low frequency domain, only two types of wave can propagate: the first antisymmetric Lamb wave (A0) and the first symmetric Lamb wave (S0). When the plate is immersed in water the A0 wave is modified and the new wave is named A wave. In this work, experimental and numerical analysis of vibration modes in a plate are carried out. The studied rectangular plate of thickness 10 mm is made of steel. Its length and width are respectively 1.0 m and 0.5 m. The plate is partially immersed in water (90%). Flexural vibrations are generated by a shaker normally connected to the emerging plate part. The applied signal is one sinusoidal period at a frequency which is under the critical frequency. Relations between the admittance of the plate and the radiated pressure in water are highlighted.
Broadband elastic scattering by fiberglass spherical shells and plates measured in a water tank: Acoustic inversion and wave analysis
Authors: Tesei Alessandra , Fox Paul D. , Robb Gary B.
Published: May 2008

Spherical shells and plane plates made of different types of fiberglass (either random or textured) were measured in the backscatter direction, suspended in a water tank in a broadband frequency range between 30 and 350 kHz. The range of ka for the spheres was approximately 8 to 90, with the fd range for the plates approximately 0.15 to 1.75 MHz*m. The aim of the study was to investigate the effects of the fiber type on the object signature, as the frequency and the type of fiber layers vary. Inversion of the material parameters was conducted on the basis of the object's temporal echo. In particular, the estimate of material loss is crucial to determine at what frequency elasticity becomes irrelevant to the object's global response. The spherical shells were measured either void or filled with different materials (liquid and solid) in order to evaluate the contribution of the shell-borne elastic waves with respect to sound scattered from the interior of the object. Elastic wave analysis and analytical modeling tools were used to support the physical interpretation of the measured responses from the different objects.
Modal analysis of resonances of an elliptic elastic cylinder immersed in water
Authors: Leon Fernand , Chati Farid , Conoir Jean-Marc
Published: May 2008

Considerable work has been done on the scattering by cylindrical objects having a circular cross section. The modal formalism based on the theory of elasticity has been developed for studying the acoustic scattering by these elastic cylinders immersed in water. In particular, it has been demonstrated, in normal incidence, that the eigenfrequencies of a circular cylinder can be determined from a resonance spectrum. These eigenfrequencies correspond to circumferential waves that form a resonance when a phase matching along a closed path is obtained. Each eigenfrequency is characterized by a given mode n, i.e., the number of wavelengths spanning the circumference. Comparatively, little attention has been devoted to the more general case of the noncircular cylindrical cylinders such as the elliptical elastic cylinders. For these objects, we have been developed a modal formalism based on the theory of elasticity. From the results obtained theoretically and experimentally, we show how to obtain a resonance spectrum, independently of the azimuth incident angle and of the radii ratio (minor radius and major radius) so that the eigenfrequencies can be determined. We present also a modal analysis of resonances as function of the azimuth incident angle and of the radii ratio.
High frequency propagation in and scattering from water-saturated granular sediments: Laboratory study
Authors: Ivakin Anatoliy N. , Sessarego Jean-Pierre
Published: May 2008

Acoustic properties of water-saturated granular sediments at frequencies from 150 kHz to 8 MHz were studied in controlled laboratory conditions using broadband transducers. Two samples of medium sand sediments, with the same mean grain size, but with different width of the size distribution, were taken for the study, degassed, and their surface was flattened. Another sample of sediments was composed of glass beads of the same grain size. The main difference of glass beads from sand grains was their shape. Backscattering strength at normal and oblique incidence and reflection coefficient at normal incidence were measured for the three samples. The reflection experiments were made for different thicknesses of the samples, so that reflections from both first and second interfaces of the sediment layer were measured. This allowed also estimating sound speed and attenuation in the sediments. The results obtained for the three chosen types of the sediments were compared to demonstrate effects of the grain size distribution width and the grain shape on acoustic properties of the sediment. [Work supported by ONR and CNRS].
A time domain model of scattering from small discrete volume particles: Tank validation
Authors: Canepa Gaetano , Sessarego Jean-Pierre , Tesei Alessandra , Guillermin Régine , Soukup Raymond J.
Published: May 2008

A model of the time domain scattering from small discrete volume particles is presented here with an experimental validation. The model was implemented on the backbone of the BORIS-3D model which originally included only surface scattering and volume scattering from small perturbation of the volume density and sound speed. The proposed model adds discrete volume scattering and simulates both monostatic and bistatic configurations. The experimental validation was performed in a tank of the CMRS/LMA Laboratory (Laboratoire de Mécanique et d'Acoustique) using an in-house produced silicon plate (with a flat upper interface) in which 10% of the volume embeds spherical glass beads 1 mm in diameter. The characteristics of this plate was well known; in particular, the amplitude of the volume backscattering (as a function of the scattering angle) has already been presented. In this work, we are particularly interested in the time domain evolution of the scattered echo. The results of this study show a very good agreement between simulated and experimental data in both amplitude and time evolution shape.
Acoustic characterization of the ancient theatre at Syracuse
Authors: Gullo Marco , La Pica Armando , Rodono' Giuseppe , Vinci Vincenzo
Published: May 2008

The ancient theatre at Syracuse, the largest open air theatre in Sicily, experienced many structural changes along its history. Today its very renowned drama festival attracts visitors from all the world that fill the entire cavea: customized seats accomodation and a prominent stage play an important role in the theatre acoustics. Because no data were available in literature on its acoustical perfomance a measurement session was carried out by our team in the framework of a wide research project on ancient theatres acoustics in the modern use. From data recorded "room criteria" parameters have been evaluated together with spectral analysis in order to gain a deeper information on the acoustic field. Main results are listed and commented and a comparison among data collected on field during the team experience in the past years is reported.
Musical granite pillars in ancient Hindu temples
Authors: Calamia Paul , Braasch Jonas
Published: May 2008

In some ancient Hindu temples built in India between the 7th century and the 16th century can be found a fascinating architectural element: intricately designed musical pillars of solid granite. These pillars, clusters of which were often carved from a single piece of stone, were tuned by means of their length, width, and tension (induced by a load from above) and were played to accompany devotional readings and dance performances. Various tunings and sound characteristics were employed based on the intended purpose. In this paper, examples of extant pillars will be presented and discussed within the context of their acoustical and architectural significance.
Convolution-scattering model for staircase echoes at the temple of Kukulkan
Authors: Lubman David
Published: May 2008

Chirped echoes from staircases at the temple of Kukulkan at Chichen Itza have stimulated much interest since first reported at scientific meetings by the author in 1998. Among them are Declercq et al (J. Acoust. Soc. Am. 116, (6) 2004). They correctly observed that the echo depends strongly on the "type" of incident sound, but offered no explanation. Those authors overlooked an earlier explanation given at the First Pan-American/Iberian Meeting on Acoustics at Cancun, Mexico (Lubman, J. Acoust. Soc. Am. 112, (5) (2002). It included a mathematical model of the chirped echo effect and a full simulation of the chirped echo, including auralization. This model explicitly shows echo dependence on the time-frequency structure of the impinging sound. With it, ethnomusicologists and others can conveniently simulate the staircase echo for any recorded sound stimulus, including handclaps, voices, and ethnic sound instruments. The clap-echo system is modeled as a time-invariant linear system. The echo time series is found by convolving the stimulus (e.g., handclap) with the staircase impulse response. This earlier model is far more computationally efficient than the Declercq model, and achieves greater accuracy by avoiding the false and needless assumptions of plane wave propagation and infinite corrugated periodic surfaces.
Auditory capacities of human fossils: A new approach to the origin of speech
Authors: Martínez Ignacio , Quam Rolf Michael , Rosa Manuel , Jarabo Pilar , Lorenzo Carlos , Arsuaga Juan Luis
Published: May 2008

The origin and evolution of human language has mainly dealt with the reconstruction of the upper respiratory tract of human fossils. After decades of controversy no clear results have arisen from these studies. We propose a new approach to this issue based on the possibility to reconstruct the sound power transmission, through the external and middle ear, in fossil specimens. The results thus obtained in the more than 500 ky old fossils from the Sima de los Huesos site (Sierra de Atapuerca, Spain) show that this hominins had the same auditory capacities as modern human, suggesting an older origin for speech than any previous study.
Acoustical reconstruction of San Petronio Basilica in Bologna during the Baroque period: the effect of festive decorations
Authors: Martellotta Francesco , Cirillo Ettore , Della Crociata Sabrina , Gasparini Emanuele , Preziuso Daniela
Published: May 2008

The Basilica of San Petronio in Bologna (Italy) is a large Gothic church characterized by three naves divided by cluster piers made of brick and flanked by square chapels. It is 130 m long, 60 m wide and 44 m high, developing a volume of 170000 m3. The widespread use of smooth plaster and the substantial lack of decoration give rise to a reverberation time (in unoccupied conditions) which varies from about 13 s at 125 Hz to 5 s at 4 kHz, with an average of 10.7 s at mid frequencies. In occupied conditions the expected mid-frequency reverberation time should lower to about 7 s. Nonetheless, these acoustic conditions appear scarcely compatible with the characteristics of the Baroque music which was composed for the "Cappella musicale" during the 17th century. However, historical research pointed out how, in that period, rich draping and curtains were often used during the major religious and civil celebrations. The analysis of the acoustic consequences of such temporary installations was performed by means of acoustic simulation based on historical records calibrated on the current configuration of the church. The paper presents the results of such reconstruction.
Ultrasonic quantitative strength assessment of artificially aged and archaeological wood samples
Authors: Salmi Ari , Steffen Kari , Eskelinen Joona , Hæggström Edward
Published: May 2008

A large fraction of discovered archaeological artefacts are wooden. Since materials grow brittle and their stiffness decreases over time, it is vital for archaeologists to have methods that assess the strength of the object prior to moving it. We present preliminary shear and elastic modulus data measured using 100 kHz longitudinal and shear ultrasonic tone burst through-transmission. Artificially aged wooden samples and archaeological samples of known age were used to validate the aging procedure by comparison of the shear and elastic modulus. We also measured the modulae of water-logged samples obtained from the ship wreck Vrouw Maria sunken in the Finnish archipelago in 1771, and compared to samples artificially aged to similar age. Scanning electron microscopy (SEM) was used to compare the structure of artificially and naturally aged samples. The results presented may be used to create an artefact model for strength assessment, and to give guidelines of strength vs. age for archaeologists to support their logistics decisions.
Possible correlation between acoustic and thermal performances of building structures
Authors: Semprini Giovanni , Cocchi Alessandro , Marinosci Cosimo
Published: May 2008

Most European standards required high performance values for sound and thermal insulation in building structures, according to Directive EEC 89/106. Sound transmission and heat transfer in structures have different physical and analytical approach and specific parameters of performance (i.e. sound transmission loss or thermal transmittance) are not directly correlated each others; many kind of structures have also different behaviour depending on mechanical properties of materials, numbers of layers of materials, etc. The aim of this work is to analyse possible correlation between sound transmission performances and thermal properties values in order to evaluated common trends related to physical properties of the various building components, like for example density or surface mass.
Efficiency of two-dimensional interpolation algorithms for high-quality dynamic binaural synthesis
Authors: Helwani Karim , Lindau Alexander , Weinzierl Stefan
Published: May 2008

Binaural synthesis of acoustical environments is based on binaural room impulse responses (BRIRs) measured with an angular resolution of typically between 1° and 15°. Considering the size of the resulting BRIR database used for auralization and the long measurement duration for its acquisition, it is reasonable to use interpolation from a lower resolution BRIR grid. Based on a mathematical formulation of the interpolation problem for BRIRs, a set of different solutions for two-dimensional spaces is described and compared with regard to efficiency and real time performance. In order to evaluate the degradation introduced by interpolation, different methods have been implemented and applied to a HRTF and a BRIR database measured in two degrees of freedom with 1°/1° horizontal/vertical resolution. These are bilinear interpolation (i.e. nearest neighbour, inverse distance weighting), spherical spline interpolation, wavelet interpolation, and interpolation based on principal component analysis (PCA). A listening test following an ABX procedure has been performed to evaluate the efficiency of the different interpolation methods according to the detection rates of interpolated versus measured BRIR databases in a dynamically auralized acoustical environment.
Comparing the sound absorption of different objects
Authors: Hickling Robert , Kopko John , Saha Pranab
Published: May 2008

Current methods of measuring sound absorption involve a piece of material. Small pieces are tested in impedance tubes. Larger pieces are tested in a reverberation room, using the reverberation-time decay method, as in ISO Standard 354. However these procedures do not determine the absorption of a complete object. It is proposed to determine the absorption of an object by measuring the negative sound power of the object in a reverberation room using sound intensity. It has been shown that sound power using sound intensity can be measured accurately in reverberation rooms (R. Hickling, Proceedings NOISE-CON 97, pages 483-488). Negative sound power on its own, however, cannot provide a satisfactory comparison indicator between objects because it depends on the room. It is necessary, therefore, to develop a normalization procedure to make the negative sound-power measurement independent of the room. A procedure is described which was tested for the same object (a car seat) in two different reverberation rooms. The results are encouraging. It is planned to conduct further tests using a variety of objects in different rooms to check the validity of the normalization procedure.
The Royal Church of San Lorenzo in Turin: Guarino Guarini and the Baroque architectural acoustics
Authors: Caniato Marco , Bettarello Federica , Masoero Marco
Published: May 2008

In 1666 the architect Guarino Guarini received from Carlo Emanuele II, Duke of Savoy, the appointment to build in Turin a new church dedicated to S. Lorenzo. The architect conceived a design in Baroque style with a very particular ribbed dome and this peculiarity is a very hard to find feature throughout Europe. Acoustics measurements were performed in S. Lorenzo in order to investigate how this unique architecture affects the response parameters used in architectural acoustics. Results are discussed in the paper, comparing to the methodology suggested by Cirillo and Martellotta in order to characterize the acoustics of churches.
Bernardo Antonio Vittone: acoustics and architecture in the XVIII century
Authors: Caniato Marco , Fasoli Vilma
Published: May 2008

Contemporary critics have identified Savoy architect Bernardo Vittone as a major contributor to the establishment of the concept and experience of architecture as the "art of construction" in the 18th century. Vittone grew and worked under the guidance of mathematician Guarino Guarini, whose mastery of theoretical and scientific aspects he was never credited to have matched. Vittone's approach to architecture was mainly practical, his plans chiefly derived from the rules of mechanics and descriptive geometry. Experience was his main source of inspiration. Designs, plans, domes and vaults are but ways to achieve balance and harmony and so are precision and control of the relation between geometry and acoustics, architecture and music. In his book "Alternative instructions on the civil Architecture" morover he included in the second appendix the "Armonic instructions", within a dissertation on the nature of sound, its propagation in open spaces, in closed ones and its relation with music. In this paper a commented overview is given matching his description of acoustics with present-day knowledge.
Architectural Acoustics Design using Diffusing Surfaces
Authors: Heddle James
Published: May 2008

This paper reviews the design challenges and development of acoustic treatments for three acoustical design projects in Australia. The projects that will be outlined were a surround sound widescreen lecture theatre, a contemporary council chambers and the rectification of a problematic brass band practice room. The treatments included sound diffusing surfaces of the geometric type with or without embedded amplitude reflection gratings. Where the gratings were used in multiples the designs also addressed periodicity issues using modulation of the grating patterns with the best known merit factors. The design approach and the development of the acoustical surface features and treatments to solve the design issues, including problems experienced in the building phase, will be discussed.
Evaluation of existing sound system designs in mosques and alternative modern solutions
Authors: Orfali Wasim , Ahnert Wolfgang
Published: May 2008

Sound intelligibly and audibility was from the old days and will remain a central issue in any sound system design especially in mosques. In other worship spaces sound system may not be needed during specific worshiping modes like congregational prayers. In mosques all worshiping modes require professionally designed sound system to maintain the needed intelligibility and audibility levels in such spaces. Here the current used sound systems in mosques will be discussed and pro and cons will be highlighted. Also, the effect of these systems on mosques applicable sound parameter will be introduced. In the same time, modern sound system design solution for different mosques architectural form and size will be suggested. Case study examples will be used to show the advantages of the new suggested sound system configurations.
Room acoustics enhancement system in a Multifunctional Cultural Centre
Authors: Balogh, Jr. Géza , Balogh, Dr. Géza
Published: May 2008

In the lecture, we present our system called DCR (Digital Control of Reverberation), which is capable of changing the reverberation of a room by means of electroacoustical devices. Using the DCR system, we are able to change the enclosure, i.e. we create an electroacoustical enclosure on the walls and on the ceiling. The parameters of the electroacoustical enclosure can be changed in several steps. The system was installed in Hungary for the first time in the city of Debrecen, in the Kölcsey Cultural Centre. The principle of the DCR and the problems and their solutions will be presented via this specific installation. We study the effect of the distance between the microphones and the loudspeakers, and the factors that influence this effect. We also analyse the room acoustics parameters in respect to the frequency, in the different status of the auditorium. Our room acoustics enhancement DCR system is based on the non-inline principle, thus the room acoustics of the large auditorium (1100 seats) of the Kölcsey Centre remained absolutely natural. We use several numbers of independent digital channels in the system, and each channel consists of one microphone, one or two loudspeakers, a power amplifier and a DSP.
The examination of the influence of standing waves on reverberation time measurements in small reverberant rooms
Authors: Horvat Marko , Jambrosic Kristian , Domitrovic Hrvoje
Published: May 2008

The measurements of reverberation time are performed in a small and rather reverberant shoe-box type room in order to determine the spatial distribution of reverberation time with respect to the formation of standing waves in the room itself. The measurements are made in a two-axes raster with equidistant distribution of measurement points. The goal is to investigate the conclusions made in an earlier work by Graber et al. that the distribution of reverberation time values along the fore mentioned raster reaches maximum values at the points of minimum sound pressure level andvice versa. The room in which the measurements are made is deliberately chosen to be relatively small in order to examine the lowest modes of standing waves that form in the room.
Student project of building an impedance tube
Authors: Suhanek Mia , Jambrosic Kristian , Domitrovic Hrvoje
Published: May 2008

This paper describes a student project of building an impedance tube for measuring the absorption coefficient using the transfer-function method, in accordance with the standard ISO 10534-2. This method is well-established and has many advantages compared to the older method using standing wave ratio (ISO 10354-1) in terms of measurement speed and accuracy. For the tube, only inexpensive materials and transducers were used. The tube was designed for the frequency range between 90 and 2000 Hz. In order to achieve this range with one tube, three microphone positions have been used. The resulting absorption coefficient has been calculated using the one- and two-microphone method. Different broadband excitation signals have been used in order to compare their robustness, such as MLS, frequency sweep and white noise. Various problems with the design and construction are addressed and the optimal configuration is discussed.
Uncertainty of airborne sound insulation index measurement in laboratory conditions
Authors: Wszolek Tadeusz
Published: May 2008

In buildings, airborne sound insulation is used to define the acoustic quality of walls between rooms. However the evaluation of sound insulation is sometimes difficult or even ambiguous, both in field and laboratory measurements, in spite of the fact that there are some unified measurement procedures specified in the ISO 140 standards. There are problems with the reproducibility and repeatability of the measured results. Some difficulties may be caused by non-diffuse acoustic fields, non uniform reverberation time or large spread of the reverberation time measurements especially in low frequency band. Some minor problems are also posed by flanking transmission and the S/N ratio. In the present work partial uncertainty analysis has been carried out for all the above mentioned factors and their influence has been evaluated on the combined uncertainty in 1/3 octave bands and the Rw index, using the uncertainty propagation law