AES New York 2019
Paper Session P17
P17 - Product Development
Saturday, October 19, 3:00 pm — 5:30 pm
Phil Brown, Dolby Laboratories - San Francisco, CA, USA
P17-1 Summed Efficiency-Method for Efficient Vented Box Speaker Design—Niels Elkjær Iversen, Technical University of Denmark - Kogens Lyngby, Denmark; Theis Christensen, ICEpower - Søborg, Denmark; Anders Bjørnskov, ICEpower - Søborg, Denmark; Lars Petersen, ICEpower A/S - Søborg, Denmark
Loudspeakers are inefficient and conventional design methods do not consider the efficiency in the design process. With the rise of Digital Signal Processing (DSP) the frequency response can be corrected with pre-filtering. Based on a frequency domain analysis of vented box enclosures this paper proposes a new method, the Summed efficiency-method (S?-method), for designing vented box enclosures. The method focuses on mapping the efficiency and SPL output vs. volume and tuning frequency enabling the designer to perform knowledge-based trade-off decisions in the design process. A design example shows how the method can be used to improve the efficiency with over 70% compared to a conventional maximum flat alignment for a compact Public Address (PA) subwoofer application.
Convention Paper 10310
P17-2 Loudspeaker Port Design for Optimal Performance and Listening Experience—Andri Bezzola, Samsung Electronics - Valencia, CA USA; Allan Devantier, Samsung Research America, Audio Lab - Valencia, CA, USA; Elisabeth McMullin, Samsung Research America - Valencia, CA USA
Bass reflex ports produce noise at high sound-pressure levels due to turbulence and vortex shedding. Flared ports can reduce port noise compared to straight ports, but the optimal flare rate in ports has remained an unsolved problem. This work demonstrates that there is in fact an optimal amount of flare, and it proposes a design method based on acoustic Finite Element simulations to efficiently predict the optimal flare rate for given port dimensions. Optimality of the flare rate is confirmed with noise and compression measurements as well as double-blind listening tests. At onset of unwanted port noise, optimally flared ports can be played 1 to 3 dB louder than slightly under-flared or over-flared ports, and 10 to 16 dB louder than straight ports.
Convention Paper 10311
P17-3 A Method for Three-Dimensional Horn Geometry Optimization—Christoper Smolen, QSC, LLC - Costa Mesa, CA, USA; Jerome Halley, QSC Audio Products LLC - Costa Mesa, CA, USA
A method for three dimensional (3D) horn geometry optimization is introduced. The method uses 3D Computer Aided Design (CAD) combined with Finite Element Analysis (FEA), the Boundary Element Method (BEM) and scientific programming where: the acoustical properties of horn geometry parametrized in CAD are analyzed using FEA and BEM, and scientific programming is used to manipulate the parametrized geometry and optimize the horn according to specified objective functions. The example of a horn design using this method is presented together with measurements of the resulting geometry.
Convention Paper 10312
P17-4 A Perceptually-Motivated Headphone Transparency Algorithm—Josh Lando, Dolby Laboratories - San Francisco, CA, USA; Alex Brandmeyer, Dolby Laboratories - San Francisco, CA, USA; Phil Brown, Dolby Laboratories - San Francisco, CA, USA; Alan Seefeldt, Dolby Labs - San Francisco, CA, USA; Andy Jaspar, Dolby Laboratories - San Francisco, CA, USA
Many modern closed-back wireless headphones now support a user-selectable “hear-through” or “transparency” feature to allow the wearer to monitor their environment. These products typically work by passively mixing the signals from external microphones with the primary media being reproduced by the headphone’s internal speakers. When there is no media playing back, that approach works reasonably well. However, once media is playing, it tends to mask the passthrough of the external audio and the wearer can no longer hear the outside world. Here we describe a perceptually motivated algorithm for improving audibility of the external microphone signals without compromising the media playback experience. Subjective test results of this algorithm as implemented in a consumer headphone product are presented.
Convention Paper 10313
P17-5 Temporal Envelope-Based Psychoacoustic Modelling for Evaluating Non-Waveform Preserving Audio Codecs—Steven van de Par, University of Oldenburg - Oldenburg, Germany; Sascha Disch, Fraunhofer IIS - Erlangen, Germany; Andreas Niedermeier, Fraunhofer Institute for Integrated Circuits IIS - Erlangen, Germany; Elena Burdiel Pérez, Fraunhofer IIS - Erlangen, Germany; Bernd Edler, Friedrich Alexander University - Erlangen-Nürnberg, Germany; Fraunhofer IIS - Erlangen, Germany
Masking models that evaluate the audibility of error signals have a limited validity for assessing perceptual quality of parametric codecs. We propose a model that transforms the audio signal into an Internal Representation (IR) consisting of temporal-envelope modulation patterns. Subsequently, the IR of original and encoded signals are compared between both signals. Even though the audio signals compared may be uncorrelated, leading to a large error signal, they may exhibit a very similar IR and hence are predicted to sound very similar. Additional post-processing stages modeling higher-level auditory perceptual phenomena such as Comodulation Masking Release are included. Predictions are compared against subjective quality assessment results obtained with encoding methods ranging from parametric processing methods up to classic waveform preserving codecs.
Convention Paper 10314