Optimizing Source and Sensor Placement for Sound Field Control: An Overview

International audienceIn order to control an acoustic field inside a target region, it is important to choose suitable positions of secondary sources (loudspeakers) and sensors (control points/microphones). This paper provides an overview of state-of-the-art source and sensor placement methods in sound field control. Although the placement of both sources and sensors greatly affects control accuracy and filter stability, their joint optimization has not been thoroughly investigated in the acoustics literature. In this context, we reformulate five general source and/or sensor placement methods that can be applied for sound field control. We compare the performance of these methods through extensive numerical simulations in both narrowband and broadband scenarios. Index Terms-source and sensor placement, sound field control , sound field reproduction, subset selection, interpolation

Spatial Multizone Soundfield Reproduction Design

It is desirable for people sharing a physical space to access different multimedia information streams simultaneously. For a good user experience, the interference of the different streams should be held to a minimum. This is straightforward for the video component but currently difficult for the audio sound component. Spatial multizone soundfield reproduction, which aims to provide an individual sound environment to each of a set of listeners without the use of physical isolation or headphones, has drawn significant attention of researchers in recent years. The realization of multizone soundfield reproduction is a conceptually challenging problem as currently most of the soundfield reproduction techniques concentrate on a single zone. This thesis considers the theory and design of a multizone soundfield reproduction system using arrays of loudspeakers in given complex environments. We first introduce a novel method for spatial multizone soundfield reproduction based on describing the desired multizone soundfield as an orthogonal expansion of formulated basis functions over the desired reproduction region. This provides the theoretical basis of both 2-D (height invariant) and 3-D soundfield reproduction for this work. We then extend the reproduction of the multizone soundfield over the desired region to reverberant environments, which is based on the identification of the acoustic transfer function (ATF) from the loudspeaker over the desired reproduction region using sparse methods. The simulation results confirm that the method leads to a significantly reduced number of required microphones for an accurate multizone sound reproduction compared with the state of the art, while it also facilitates the reproduction over a wide frequency range. In addition, we focus on the improvements of the proposed multizone reproduction system with regard to practical implementation. The so-called 2.5D multizone oundfield reproduction is considered to accurately reproduce the desired multizone soundfield over a selected 2-D plane at the height approximately level with the listener’s ears using a single array of loudspeakers with 3-D reverberant settings. Then, we propose an adaptive reverberation cancelation method for the multizone soundfield reproduction within the desired region and simplify the prior soundfield measurement process. Simulation results suggest that the proposed method provides a faster convergence rate than the comparative approaches under the same hardware provision. Finally, we conduct the real-world implementation based on the proposed theoretical work. The experimental results show that we can achieve a very noticeable acoustic energy contrast between the signals recorded in the bright zone and the quiet zone, especially for the system implementation with reverberation equalization

A room acoustics measurement system using non-invasive microphone arrays

This thesis summarises research into adaptive room correction for small rooms and pre-recorded material, for example music of films. A measurement system to predict the sound at a remote location within a room, without a microphone at that location was investigated. This would allow the sound within a room to be adaptively manipulated to ensure that all listeners received optimum sound, therefore increasing their enjoyment. The solution presented used small microphone arrays, mounted on the room's walls. A unique geometry and processing system was designed, incorporating three processing stages, temporal, spatial and spectral. The temporal processing identifies individual reflection arrival times from the recorded data. Spatial processing estimates the angles of arrival of the reflections so that the three-dimensional coordinates of the reflections' origin can be calculated. The spectral processing then estimates the frequency response of the reflection. These estimates allow a mathematical model of the room to be calculated, based on the acoustic measurements made in the actual room. The model can then be used to predict the sound at different locations within the room. A simulated model of a room was produced to allow fast development of algorithms. Measurements in real rooms were then conducted and analysed to verify the theoretical models developed and to aid further development of the system. Results from these measurements and simulations, for each processing stage are presented

Structured Sparsity Models for Multiparty Speech Recovery from Reverberant Recordings

We tackle the multi-party speech recovery problem through modeling the acoustic of the reverberant chambers. Our approach exploits structured sparsity models to perform room modeling and speech recovery. We propose a scheme for characterizing the room acoustic from the unknown competing speech sources relying on localization of the early images of the speakers by sparse approximation of the spatial spectra of the virtual sources in a free-space model. The images are then clustered exploiting the low-rank structure of the spectro-temporal components belonging to each source. This enables us to identify the early support of the room impulse response function and its unique map to the room geometry. To further tackle the ambiguity of the reflection ratios, we propose a novel formulation of the reverberation model and estimate the absorption coefficients through a convex optimization exploiting joint sparsity model formulated upon spatio-spectral sparsity of concurrent speech representation. The acoustic parameters are then incorporated for separating individual speech signals through either structured sparse recovery or inverse filtering the acoustic channels. The experiments conducted on real data recordings demonstrate the effectiveness of the proposed approach for multi-party speech recovery and recognition.Comment: 31 page

Proceedings of the EAA Spatial Audio Signal Processing symposium: SASP 2019

International audienc

Engineering data compendium. Human perception and performance. User's guide

The concept underlying the Engineering Data Compendium was the product of a research and development program (Integrated Perceptual Information for Designers project) aimed at facilitating the application of basic research findings in human performance to the design and military crew systems. The principal objective was to develop a workable strategy for: (1) identifying and distilling information of potential value to system design from the existing research literature, and (2) presenting this technical information in a way that would aid its accessibility, interpretability, and applicability by systems designers. The present four volumes of the Engineering Data Compendium represent the first implementation of this strategy. This is the first volume, the User's Guide, containing a description of the program and instructions for its use

Soundfield representation, reconstruction and perception

This thesis covers the area of soundfield representation, reconstruction and perception. The complexity and information content of a soundfield presents many mathematical and engineering challenges for accurate reconstruction. After an in-depth review of the field of mathematical soundfield representation, an analysis of the numerical and practical constraints for soundfield reconstruction is presented. A review of work in experimental psycho-acoustics higlights the variability of spatial sound perception. It is shown that the error and uncertainty in perception is of a comparable magnitude to the accuracy achievable by present soundfield systems. Therefore, the effects of hearing adaption, sensory bias, sensory conflict, and contextual memory cannot be ignored. If the listening environment is inappropriate or in conflict with the desired perceptual experience, little is gained from more complex soundfield representation or reconstruction. The imp! lications of this result to the delivery of spatial audio is discussed and some open problems for further exploration and experimentation are detailed

How recording studios used technology to invoke the psychedelic experience: the difference in staging techniques in British and American recordings in the late 1960s

This thesis focuses on a time in the mid-1960s where practice in the studio changed from a formal arena where previously rehearsed songs were recorded, to a playground where sonic possibilities were explored and sound manipulation became normal practice. This abuse of technology and manipulation of reality became part of the creative process in the studio, providing soundscapes that resonated with the counter-cultural ethos of upsetting the established order, and were adopted by the mainstream during the 1967 ‘Summer of Love”. Following a discussion of current literature, practice as research is applied to demonstrate how interaction with historical technology reveals the performative nature of the tacit knowledge that created many of the aural effects under consideration. The research then focuses through the prism of two case studies, “Eight Miles High” recorded by The Byrds in Los Angeles in January 1966, and “Rain”, recorded by The Beatles in London in April 1966. Through re-enactment of these historical recording sessions, I recreate the closed envirnment of the 1960’s recording studio. By interacting with historical technology and following a similar structure to the original sessions, I investigate how the methodology was influenced by collaborative actions, situational awareness and the demarcation of roles. Post session video analysis reveals the flow of decision making as the sessions unfold, and how interaction with the technological constraints recreates ‘forgotten’ techniques that were deemed everyday practice at the time and were vital to the outcome of the soundscapes. The thesis combines theory and practice to develop an understanding of how the engineers interacted with technology (Polanyi, 1966), often abusing the equipment to create manipulated soundscapes (Akrich and Latour, 1992), and how the sessions responded to musicians demanding innovation and experimentation, circumventing the constraints of established networks of practice (Law and Callon, 1986) during the flow of the recording session. (Ingold, 2013