AES New York 2017
Poster Session P13
P13 - Transducers
Friday, October 20, 11:00 am — 12:30 pm (Poster Area)
P13-1 Equalization of Localized Sources on Flat-Panel Audio Displays—Michael Heilemann, University of Rochester - Rochester, NY, USA; David Anderson, University of Rochester - Rochester, NY, USA; Mark F. Bocko, University of Rochester - Rochester, NY, USA
An equalization method is presented for sound sources rendered by eigenmode superposition on flat-panel audio displays. A filter is designed to provide a constant mechanical acceleration for each localized source region at all frequencies below the spatial aliasing frequency of the actuator array used to excite the panel’s bending modes. Within this bandwidth, the vibration profile of the source remains consistent with the application of the equalization filter, preserving any spatial information conveyed to the listener from the source position. Directivity simulations and measurements show that these localized source regions do not exhibit the irregular directivity characteristic of single and multi-actuator distributed mode loudspeakers, but instead exhibit radiation characteristics similar to conventional piston loudspeakers within the array bandwidth.
Convention Paper 9871 (Purchase now)
P13-2 Loudspeaker 3D Directivity Estimation with First Order Microphone Measurements on a 2D Plane—Lachlan Birnie, Australian National University - Canberra, Australia; Thushara Abhayapala, Australian National University - Canberra, ACT, Australia; Prasanga Samarasinghe, Australian National University - Canberra, Australia
This paper proposes an efficient method to estimate the 3D directivity pattern of loudspeakers or portable devices with embedded speakers. We place the loudspeaker on a horizontal turntable and use a first order microphone located on the horizontal plane to measure pressure and pressure gradients along three orthogonal directions to construct equivalent virtual arrays of first order microphones on the horizontal plane. By exploiting the properties of the associated Legendre functions, we construct the 3D directivity pattern of the loudspeaker over frequencies. The method is equivalent to having a measurement setup consist of a dense spherical array encompassing the loudspeaker. The underlying theory and method are corroborated by simulations as well as measurements of the directivity of a physical loudspeaker.
Convention Paper 9872 (Purchase now)
P13-3 A Headphone Measurement System Covers both Audible Frequency and beyond 20 kHz (Part 3)—Naotaka Tsunoda, Sony Corporation - Shinagawa-ku, Tokyo, Japan; Takeshi Hara, Sony Video & Sound Products Inc. - Tokyo, Japan; Koji Nageno, Sony Video and Sound Corporation - Tokyo, Japan
New headphone frequency response measuring scheme was standardized as JEITA RC-8140B-1 in March 2016. The basic idea of the scheme is that the frequency response is to be measured by HATS and compensated by a free-field HRTF of HATS used in the measurement. One of the advantages of this measuring scheme is that obtained results have equivalent implication with the results of free-field frequency response of the loudspeakers. This report supplements the previous report that proposed the basic idea of above-mentioned scheme by adding topics regarding newly developed HATS to improve signal to noise ratio in high frequency areas above 20 kHz with ear simulators.
Convention Paper 9873 (Purchase now)
P13-4 Novel Type of MEMS Loudspeaker Featuring Membrane-Less Two-Way Sound Generation—Fabian Stoppel, Fraunhofer Institute for Silicon Technology ISIT - Itzehoe, Germany; Florian Niekiel, Fraunhofer Institute for Silicon Technology ISIT - Itzehoe, Germany; Thorsten Giese, Fraunhofer Institute for Silicon Technology ISIT - Itzehoe, Germany; Shanshan Gu-Stoppel, Fraunhofer Institute for Silicon Technology ISIT - Itzehoe, Germany; Andreas Männchen, Fraunhofer Institute for Digital Media Technology IDMT - Ilmenau, Germany; Johannes Nowak, Fraunhofer Institute for Digital Media Technology IDMT - Ilmenau, Germany; Daniel Beer, Fraunhofer Institute for Digital Media Technology IDMT - Ilmenau, Germany; Bernhard Wagner, Fraunhofer Institute for Silicon Technology ISIT - Itzehoe, Germany
In this paper a novel type of piezoelectric microelectromechanical loudspeaker is presented. The device concept is based on concentrically cascaded lead zirconate titanate actuators making it the first integrated two-way MEMS speaker reported. As a further novelty, the device is designed to operate without a closed membrane significantly improving the acoustic performance, energy efficiency, and manufacturability. Extensive finite element analysis studies have revealed a very high SPL of more than 79 dB in 10 cm distance at 500 Hz for a device 1 cm² in size operated at 30 V. At higher frequencies even larger SPL values are calculated enabling a flat frequency response with 89 dB for frequencies above 800 Hz. Based on this concept first speaker prototypes have been fabricated using MEMS technology.
Convention Paper 9874 (Purchase now)
P13-5 Analysis of the Mechanical Vibration and Acoustic Behavior of a Piezoelectric MEMS Microspeaker—Andreas Männchen, Fraunhofer Institute for Digital Media Technology IDMT - Ilmenau, Germany; Daniel Beer, Fraunhofer Institute for Digital Media Technology IDMT - Ilmenau, Germany; Florian Niekiel, Fraunhofer Institute for Silicon Technology ISIT - Itzehoe, Germany; Johannes Nowak, Fraunhofer Institute for Digital Media Technology IDMT - Ilmenau, Germany; Fabian Stoppel, Fraunhofer Institute for Silicon Technology ISIT - Itzehoe, Germany; Bernhard Wagner, Fraunhofer Institute for Silicon Technology ISIT - Itzehoe, Germany
This paper investigates the performance of a piezoelectric MEMS-based microspeaker. The performance is compared to the state of the art in terms of electrodynamic microspeakers for mobile applications. The analysis is twofold: First, the mechanical behavior is evaluated using laser interferometry and discussed for different stimuli such as sine sweeps or static sinusoidal excitation. Second, the acoustic performance is assessed by way of measurements under anechoic conditions. Results show that the speaker performs well for its size while providing low power consumption. However, in order to achieve high broadband reproduction quality, further design improvements are necessary.
Convention Paper 9875 (Purchase now)
P13-6 Auditory-Based Smoothing for Equalization of Headphone-to-Eardrum Transfer Function—Guangju Li, Key Laboratory of Noise and Vibration Research,Institute of Acoustics, Chinese Academy of Sciences; University of Chinese Academy of Sciences - Beijing, China; Ziran Jiang, Key Laboratory of Noise and Vibration Research, Institute of Acoustics, Chinese Academy of Sciences; University of Chinese Academy of Sciences - Beijing, China; Jinqiu Sang, Institute of Acoustics, Chinese Academy of Science - Beijing, China; Chengshi Zheng, Chinese Academy of Sciences - Beijing, China; Chinese Academy of Sciences - Shanghai, China; Renhua Peng, Chinese Academy of Sciences - Beijing, China; Xiaodong Li, Chinese Academy of Sciences - Beijing, China; Chinese Academy of Sciences - Shanghai, China
Binaural headphone reproduction can be improved by equalization of headphone-to-eardrum transfer function (HETF) in an appropriate way. Direct inversion of HETF targeting at a flat frequency response cannot keep the peaks and valleys due to pinna and ear canal filtering that might help auditory perception. Moreover, Direct inversion might induce annoying high Q peak values due to variability across listeners. Smoothing the HETF before direct inversion can avoid over equalization. Two auditory-based spectral smoothing methods were studied in this research. One is based on roex filtering that can simulate human auditory filtering in the basilar membrane, and the other is cepstral smoothing that can simulate the auditory perception characteristic of frequency resolution. Subjective experiments show that, in comparison to direct inversion, the two proposed methods can improve binaural headphone reproduction.
Convention Paper 9876 (Purchase now)
P13-7 Interpolation and Display of Microphone Directivity Measurements Using Higher Order Spherical Harmonics—Jonathan D. Ziegler, Stuttgart Media University - Stuttgart, Germany; Eberhard Karls University Tübingen - Tübingen, Germany; Mark Rau, Center for Computer Research in Music and Acoustics (CCRMA), Stanford University - Palo Alto, CA, USA; Andreas Schilling, Eberhard Karls University Tuebingen - Tuebingen, Germany; Andreas Koch, Stuttgart Media University - Stuttgart, Germany
The accurate display of frequency dependent polar response data of microphones has largely relied on the use of a defined set of test frequencies and a simple overlay of two-dimensional plots. In recent work, a novel approach to digital displays without fixed frequency points was introduced. Building on this, an enhanced interpolation algorithm is presented, using higher-order spherical harmonics for angular interpolation. The presented approach is compared to conventional interpolation methods in terms of computational cost and accuracy. In addition, a three-dimensional data processing prototype for the creation of interactive, frequency-dependent, three-dimensional microphone directivity plots is presented.
Convention Paper 9877 (Purchase now)