Sex differences in vocal behavior in virtual rooms compared to real rooms.

This study investigates speech production under various room acoustic conditions in virtual environments, by comparing vocal behavior and the subjective experience of speaking in four real rooms and their audio-visual virtual replicas. Sex differences were explored. Males and females (N = 13) adjusted their voice levels similarly to room acoustic changes in the real rooms, but only males did so in the virtual rooms.

Sensitivity of the predicted acoustic pressure field to the wind and temperature profiles in a conventionally neutral boundary layer.

Simulations are widely used to predict noise emissions from traffic, railroad, aircraft, and wind farms and for sound field control. The latter employs multiple sources interacting and it requires accurate phase information. Acoustic models require precise characterization of the medium properties.

Virtual reality head-mounted displays affect sidetone perception.

The purpose of this study was to investigate whether head-mounted displays (HMDs) change the sidetone to an auditory perceivable extent. Impulse responses (IRs) were recorded using a dummy head wearing a HMD (IRtest) and compared to IRs measured without HMD (IRref). Ten naive listeners were tested on their ability to discriminate between the IRtest and IRref using convolved speech signals.

A controlled chamber study of effects of exposure to diesel exhaust particles and noise on heart rate variability and endothelial function.

Background: Adverse cardiovascular effects are associated with both diesel exhaust and road traffic noise, but these exposures are hard to disentangle epidemiologically. We used an experimental setup to evaluate the impact of diesel exhaust particles and traffic noise, alone and combined, on intermediary outcomes related to the autonomic nervous system and increased cardiovascular risk.

Methods: In a controlled chamber 18 healthy adults were exposed to four scenarios in a randomized cross-over fashion.

Absorption and scattering by perforated facings with periodic narrow slits.

This paper develops a theory for the sound absorption and scattering of perforated slit absorbers. A rigid plane, perforated periodically in one dimension with absorbing slits, scatters incoming sound waves as discrete wave components in different directions. The absorbing slits are assumed to be line-like in the sense that their width is much shorter than the wavelengths.

Do Room Acoustics Affect the Amplitude of Sound-Field Auditory Steady-State Responses?

The sound-field auditory steady-state response (ASSR) is a promising measure for the objective validation of hearing-aid fitting in patients who are unable to respond to behavioral testing reliably. To record the sound-field ASSR, the stimulus is reproduced through a loudspeaker placed in front of the patient. However, the reverberation and background noise of the measurement room could reduce the stimulus modulation used for eliciting the ASSR.

Wave transmission and vibration response in periodically stiffened plates using a free wave approach.

There are various structures constructed with periodically stiffened thin plates. Vibration prediction of such structures is not easy compared to the structures comprised of uniform plates only due to the mathematical complexity stemmed from the periodic nature. This study provides the analytic method to predict the wave transmission at junctions connecting two semi-infinite periodic structures and the response of a finite periodic structure to an external harmonic point force.

Hybrid analytical-numerical optimization design methodology of acoustic metamaterials for sound insulation.

Acoustic metamaterials are becoming promising solutions for many industry applications, but the gap between theory and practice is still difficult to close. This research proposes an optimization methodology of acoustic metamaterial designs for sound insulation that aims to start bridging this gap. The proposed methodology takes advantage of a hybrid analytical-numerical approach for computing the sound transmission loss of the designs efficiently.

Gaussian processes for sound field reconstruction.

This study examines the use of Gaussian process (GP) regression for sound field reconstruction. GPs enable the reconstruction of a sound field from a limited set of observations based on the use of a covariance function (a kernel) that models the spatial correlation between points in the sound field. Significantly, the approach makes it possible to quantify the uncertainty on the reconstruction in a closed form.

Large-scale outdoor sound field control.

The feasibility and the performance of controlling low frequency sound of loudspeaker systems under varying atmospheric conditions is examined experimentally. In the experiment, a control subwoofer array is canceling the sound of a primary subwoofer array over long distances (∼100 m) and in large areas (∼320 m) using the pressure-matching method. To avoid the measurement of the sound field over the entire control area, a sound propagation model is introduced that is fitted in situ to model the radiation properties of the loudspeakers and the variation of the speed of sound.

An analytical model for broadband sound transmission loss of a finite single leaf wall using a metamaterial.

Acoustic metamaterials (AM) have emerged as an academic discipline within the last decade. When used for sound insulation, metamaterials can show high transmission loss at low frequencies, despite having low mass per unit area. This paper investigates the possibility of using AMs to increase the sound insulation of finite single leaf walls (SLWs), focusing on the coincidence effect problem.

A Bayesian spherical harmonics source radiation model for sound field control.

In sound field reproduction and sound field control systems, the acoustic transfer functions between a set of sources and an extended reproduction area need to be accurately estimated in order to achieve good performance. This implies that large amounts of measurements should be performed if the area is large compared to the wavelengths of interest. In this paper, a method for reconstructing these transfer functions in highly damped conditions is proposed by using only a small number of measurements in the reproduction area.

Characterization of sound scattering using near-field pressure and particle velocity measurements.

The acoustic properties of surfaces are commonly evaluated using samples of finite size, which generate edge diffraction effects that are often disregarded. This study makes use of sound scattering theory to characterize such finite samples. In a given sound field, the samples can be described by a unique complex directivity function called the far-field pattern.

Experimental characterization of the sound field in a reverberation room.

Measured values of acoustic absorption obtained from standardized reverberation-chamber measurements often differ across laboratories. These discrepancies arise due to non-isotropic sound incidence on the absorbing specimen, diffraction at the sample edges, and differences in the chambers' shapes and dimensions. The present study examines an experimental method for characterizing the distribution of sound incidence on the specimen in the steady state.

A wavenumber approach to quantifying the isotropy of the sound field in reverberant spaces.

This study proposes an experimental method for evaluating isotropy in enclosures, based on an analysis of the wavenumber spectrum in the spherical harmonics domain. The wavenumber spectrum, which results from expanding an arbitrary sound field into a plane-wave basis, is used to characterize the spatial properties of the observed sound field. Subsequently, the obtained wavenumber spectrum is expanded into a series of spherical harmonics, and the moments from this spherical expansion are used to characterize the isotropy of the wave field.

An optical flow-based state-space model of the vocal folds.

High-speed movies of the vocal fold vibration are valuable data to reveal vocal fold features for voice pathology diagnosis. This work presents a suitable Bayesian model and a purely theoretical discussion for further development of a framework for continuum biomechanical features estimation. A linear and Gaussian nonstationary state-space model is proposed and thoroughly discussed.

Estimation of surface impedance at oblique incidence based on sparse array processing.

A method is proposed to estimate the surface impedance of a large absorptive panel from free-field measurements with a spherical microphone array. The method relies on the reconstruction of the pressure and the particle velocity on the studied surface using an equivalent source method based on spherical array measurements. The sound field measured by the array is mainly composed of an incident and a reflected wave, so it can be represented as a spatially sparse problem.

A numerical strategy for finite element modeling of frictionless asymmetric vocal fold collision.

Analysis of voice pathologies may require vocal fold models that include relevant features such as vocal fold asymmetric collision. The present study numerically addresses the problem of frictionless asymmetric collision in a self-sustained three-dimensional continuum model of the vocal folds. Theoretical background and numerical analysis of the finite-element position-based contact model are presented, along with validation.

In situ measurements of the oblique incidence sound absorption coefficient for finite sized absorbers.

Absorption coefficients are mostly measured in reverberation rooms or with impedance tubes. Since these methods are only suitable for measuring the random incidence and the normal incidence absorption coefficient, there exists an increasing need for absorption coefficient measurement of finite absorbers at oblique incidence in situ. Due to the edge diffraction effect, oblique incidence methods considering an infinite sample fail to measure the absorption coefficient at large incidence angles of finite samples.

Development and validation of a combined phased acoustical radiosity and image source model for predicting sound fields in rooms.

A model, combining acoustical radiosity and the image source method, including phase shifts on reflection, has been developed. The model is denoted Phased Acoustical Radiosity and Image Source Method (PARISM), and it has been developed in order to be able to model both specular and diffuse reflections with complex-valued and angle-dependent boundary conditions. This paper mainly describes the combination of the two models and the implementation of the angle-dependent boundary conditions.

An objective measure for the sensitivity of room impulse response and its link to a diffuse sound field.

This study is relevant to acoustic measurements in reverberation rooms such as measurements of sound transmission, sound absorption, and sound power levels of noise sources. The study presents a quantitative measure for the diffuseness in a room, which is first introduced theoretically and subsequently examined experimentally. The sensitivity of a room due to changes in the initial conditions is quantified by measuring a pair of impulse responses in a room differing only in the sound source position.

Investigation of model based beamforming and Bayesian inversion signal processing methods for seismic localization of underground sources.

Techniques have been studied for the localization of an underground source with seismic interrogation signals. Much of the work has involved defining either a P-wave acoustic model or a dispersive surface wave model to the received signal and applying the time-delay processing technique and frequency-wavenumber processing to determine the location of the underground tunnel. Considering the case of determining the location of an underground tunnel, this paper proposed two physical models, the acoustic approximation ray tracing model and the finite difference time domain three-dimensional (3D) elastic wave model to represent the received seismic signal.

The equivalent incidence angle for porous absorbers backed by a hard surface.

An equivalent incidence angle is defined as the incidence angle at which the oblique incidence absorption coefficient best approximates the random incidence absorption coefficient. Once the equivalent angle is known, the random incidence absorption coefficient can be estimated by a single experiment using a free-field absorption measurement technique with a source at the equivalent angle. This study investigates the equivalent angle for locally and extendedly reacting porous media mainly by a numerical approach: Numerical minimizations of a cost function that is the difference between the oblique incidence absorption coefficient at a specific incidence angle and the random incidence absorption coefficient.

Modal density and modal distribution of bending wave vibration fields in ribbed plates.

Plates reinforced by ribs or joists are common elements in lightweight building structures, as well as in other engineering structures such as vehicles, ships, and aircraft. These structures, however, are often not well suited for simple structural acoustic prediction models such as statistical energy analysis. One reason is that the modal density is not uniformly distributed due to the spatial periodicity introduced by the ribs.

Combination of acoustical radiosity and the image source method.

A combined model for room acoustic predictions is developed, aiming to treat both diffuse and specular reflections in a unified way. Two established methods are incorporated: acoustical radiosity, accounting for the diffuse part, and the image source method, accounting for the specular part. The model is based on conservation of acoustical energy.