144th AES CONVENTION Engineering Brief EB06: Transducers & Psychoacoustics

AES Milan 2018
Engineering Brief EB06

EB06 - Transducers & Psychoacoustics

Friday, May 25, 16:15 — 17:30 (Scala 2)

Hyunkook Lee, University of Huddersfield - Huddersfield, UK

EB06-1 Woofer Performance Variance Due to Components and Assembly ProcessMaria Costanza Bellini, University of Parma - Parma, Italy; Angelo Farina, Università di Parma - Parma, Italy
This paper presents an experimental study of the main causes of scrap during the production of a woofer loudspeaker. After analyzing the most critical components of a transducer, samples with reference and modified components have been built and characterized in terms of frequency-response and linear distortion curves and electrical, mechanical, acoustical parameters. In addition, a second set of samples has been built using reference components but varying the assembly process parameters; these samples also have been characterized as the previous ones. Measurements have been performed both in an anechoic chamber, along a production line, and inside a car. By the analysis of acquired data, the authors have individuated the most influential components and assembly parameters in terms of required performance.
Engineering Brief 446 (Download now)

EB06-2 Design and Measurement of a First-Order, Horizontally Beam-Controlling Loudspeaker CubeNils Meyer-Kahlen, University of Technology Graz - Graz, Austria; University of Music and Performaing Arts Graz; Franz Zotter, IEM, University of Music and Performing Arts - Graz, Austria; Katharina Pollack, TU Graz - Graz, Austria; University of Music and Performing Arts Graz - Graz, Austria
This paper describes a loudspeaker cube with four transducers on its horizontal facets, designed to enable sound radiation with adjustable first-order beam control. Design and equipping of the cubical loudspeaker is presented along with two open data sets containing multiple-input-multiple-output impulse responses (MIMO-IRs) of our measurements. The first one contains 648x 4 MIMO-IRs from input voltages to a grid of microphones at a fixed distance. The second set contains 4x 4 MIMO-IRs from input voltages to loudspeaker cone velocities, and it characterizes the active and passive transducer coupling through the enclosure that we aim to equalize/decouple. Based on these measurements we present a simple FIR filter design required for beam control of which we discuss operation range and limitations.
Engineering Brief 447 (Download now)

EB06-3 Ambisonics Directional Room Impulse Response as a New Convention of the Spatially Oriented Format for AcousticsAndrés Pérez-López, Eurecat - Barcelona, Spain; Pompeu Fabra University - Barcelona, Spain; Julien De Muynke, Fundacio Eurecat - Barcelona, Spain
Room Impulse Response (RIR) measurements are one of the most common ways to capture acoustic characteristics of a given space. When performed with microphone arrays, the RIRs inherently contain directional information. Due to the growing interest in Ambisonics and audio for Virtual Reality, new spherical microphone arrays recently hit the market. Accordingly, several databases of Directional RIRs (DRIRs) measured with such arrays, referred to as Ambisonics DRIRs, have been publicly released. However, there is no format consensus among databases. With the aim of improving interoperability, we propose an exchange format for Ambisonics DRIRs, as a new Spatially Oriented Format for Acoustics (SOFA) convention. As a use-case, some existing databases have been converted and released following our proposal.
Engineering Brief 448 (Download now)

EB06-4 Fidelity of Low Frequency Reproduction in Cars in a Sound Field Control ContextHans Lahti, Harman - Gothenburg, Sweden; Anders Löfgren, Volvo Cars - Torslanda, Sweden; Adrian Bahne, Dirac Research AB - München, Germany
Overall sound quality of factory-delivered automotive sound systems has reached a very high standard. Particularly branded high-end systems comprise great components and are well-tuned. The low frequency reproduction in automotive sound systems is, however, typically flawed. The most prominent flaw consists of resonant bass reproduction and undesirable spectral decay characteristics with strong ringing in wide frequency bands. To overcome this challenge, we adapt an algorithm allowing for simultaneous equalization of multiple channels, assuring full exploitation of the acoustic degrees of freedom inherent to a multichannel system. The sound field can be spatially controlled, yielding a uniform and tight reproduction of low frequencies in all regions of interest throughout the car compartment, with controlled and improved spectral decay characteristics.
Engineering Brief 449 (Download now)

EB06-5 A Distributed Audio System for Automotive ApplicationsJohannes Boehm, Paragon AG - Delbrück, Germany; Dirk Olszewski, paragon AG - Delbrück, Germany; Zafar Baig Mirza, paragon AG - Delbrück, Germany; Philipp Rathmann, paragon AG - Delbrück, Germany; Antonio Prados-Vilchez, paragon AG - Delbrück, Germany; Vitalie Botan, paragon AG - Delbrück, Germany; Juergen Binder, paragon AG - Delbrück, Germany; Klaus Rodemer, paragon AG - Delbrück, Germany
With a trend to higher levels of drivetrain electrification and autonomous driving, the technology to increase audio performance is becoming a more significant factor of request. Instead of centralizing related signal processing in a single powerful hardware platform, distributing it in a more intelligent way can lead to several advantages such as optimized cabling, reduced weight, improved system scalability, performance, and costs. The distributed audio system proposed in this work is connected to an automobile head unit that serves as human machine interface and media source. Portions of the data acquisition, signal processing, and amplification are placed within distributed processing nodes. We present a realization with 34 loudspeakers and 16 microphones featuring seat-individual 3D audio rendition, in-car communication, and further innovative use cases.
Engineering Brief 450 (Download now)

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