Auralization: fundamentals of acoustics, modelling, simulation, algorithms and acoustic virtual reality

"Auralization" is the technique of creation and reproduction of sound on the basis of computer data. With this tool is it possible to predict the character of sound signals which are generated at the source and modified by reinforcement, propagation and transmission in systems such as rooms, buildings, vehicles or other technical devices. This book is organized as a comprehensive collection of the basics of sound and vibration, acoustic modelling, simulation, signal processing and audio reproduction. Implementations of the auralization technique are described using examples drawn from various fields in acoustic’s research and engineering, architecture, sound design and virtual reality

Cómo los expertos acústicos hablan con la "gente normal"

Lo que la gente generalmente quiere saber sobre acústica es si la acústica es "buena". Los aspectos ingenieril es sobre acústica son completamente desconocidos para el público. Por ello, la discusión de problemas en acústica se simplifica generalmente utilizando números únicos, por ejemplo, el nivel expresado en "dB(A)". Sin embargo, los factores especiales sobre la calidad acústica o el impacto del ruido en la sociedad, no se pueden cuantificar fácilmente debido a la situación actual del problema acústico, ya que se deben tener en cuenta las actividades de las personas que actúan o se ven afectadas, así como el contexto general de la situación. En esta conferencia, se han introducido desarrollos recientes de simulación y auralización y se han demostrado mediante ejemplos de caracterización y evaluación del aislamiento acústico y el ruido de transportes

Broadband time-domain impedance boundary modeling with the discontinuous Galerkin method for room acoustics simulations

The time-domain nodal discontinuous Galerkin (TD-DG) method is emerging as a potential wave-based method for three-dimensional (3D) room acoustics modeling, where high-order accuracy, geometrical flexibility and accurate modeling of boundary conditions are of critical importance. In this work, an accurate and efficient formulation of broadband time-domain impedance boundary conditions of locally-reacting surfaces is proposed in the framework of the TD-DG method. The formulation of the time-domain boundary condition is based on the plane-wave reflection coefficient at normal incidence and its approximation in the frequency domain using a sum of rational fractions, which can be obtained from analytical models or measured impedance values. To verify the performance of the formulation, a single reflection scenario is considered and the reflection coefficient obtained from the numerical tests is compared with the analytical one based on a locally reacting surface impedance. Also, the effects of the coefficients of rational functions on the accuracy are investigated. The broadband time-domain impedance boundary formulation accurately predicts both the amplitude and the phase of the reflection behaviour

Pupillary correlates of auditory emotion recognition in older hearing-impaired listeners

Hearing-impaired (HI) individuals are shown to perform worse in auditory emotion recognition tasks compared to normal hearing individuals. It is still unclear if this is due to processing at low auditory levels or to categorisation of emotions that are involved in an experimental task (1). An index of emotion recognition can be observed in pupil dilations, which have recently been shown to dilate more for emotionally meaningful speech in comparison to emotionally neutral speech (2). We fitted 8 older HI participants, who had moderate to severe sloping high-frequency hearing loss, with frequency lowering enabled hearing aids for an acclimatisation period of 3-6 weeks. We recorded their pupil dilations in response to emotional speech with and without frequency lowering, during a passive-listening condition, both before and after the acclimatisation period. We also recorded their pupil dilations during an active-listening condition, which included a behavioural emotion identification task, after the acclimatisation period. We present here insights into the pupillary correlates of vocal emotion recognition in the HI population and the impact of frequency lowering and the cognitive involvement elicited by the experimental situation on pupil dilation and emotion recognition capabilities in this population

Sympathetic vibration in a piano

Sympathetic vibration is a common phenomenon in musical instruments. In the piano, strings that are not struck directly by the hammer can vibrate sympathetically due to physical coupling. This effect will, for instance, occur when the una corda pedal is used in a grand piano. When depressed, the hammer shifts rightwards so that the leftmost string will be missed, striking only 1 out of 2 (or 2 out of 3) strings in a note at a same time. In order to understand the acoustical and perceptual differences in the notes played without and with una corda pedal depressed, the recordings of a piano for these two playing conditions are studied for all 88 keys. Differences arising in the frequency domains are found and presented alongside with discrepancies in three psychoacoustical descriptors, namely log-attack-time, temporal centroid and normalised spectral centroid. Future work in the form of listening test is planned

How office workers cope with distraction by sounds in the open plan office

The open plan office is a complex sound environment existing of speech, office equipment sounds, sounds from building services and other background sounds. Each type of sound can have a different influence on the performance or well-being of the office workers. Much research reports which sound sources are perceived to be most disruptive or annoying. To some extent, acoustic measures such as sound absorption and screens can be used to reduce the intelligibility of speech or the sound level of noise sources. Nevertheless, office workers need to deal with the acoustic environment they work in. In this research it is investigated which coping strategies are used by office workers for different sounds and how these strategies are perceived to be effective for improving productivity. Questionnaires were distributed among workers in three different companies that have problems with sound. Results show that ‘discussing the noise problem with colleagues’ is perceived as the most effective strategy when intelligible speech is the problem. Less effective, but more often applied, are so-called avoidance strategies such as ‘put work off’ and ‘interrupt work’, which is striking. Ear plugs are only perceived to be effective when speech is unintelligible or other sounds are disturbing

Design and simulation of a benchmark room for room acoustic auralizations

In order to achieve accurate acoustic simulations of a room for obtaining an authentic auralization, the following aspects need to be quantified: the geometrical details of the room, all material properties and the characteristics of the source and the receiver. This paper presents the design of a benchmark room for this purpose, including all this information. The room is a building acoustics transmission chamber with thick concrete walls. This room was then acoustically treated to achieve an acoustic environment close to a day-to-day office room. The surface impedances of the materials additionally installed in the room were measured with both in the impedance tube as well as with a pressure-velocity sensor. Furthermore, the directivity of the measurement source and the binaural receiver were measured in order to be included in the simulations. Impulse responses of this benchmark room have also been obtained from simulations with the in-house time-domain discontinuous Galerkin method (DG) with frequencydependent boundary conditions, including source and receiver directivity. Time and frequency domain results from the both the measurements and simulations are presented, showing a close agreement