AES Rome 2013
Paper Session P10

P10 - Transducers—Part 2: Arrays, Microphones

Sunday, May 5, 14:15 — 17:15 (Sala Foscolo)

P10-1 The Radiation Characteristics of an Array of Horizontally Asymmetrical Waveguides that Utilize Continuous Arc Diffraction SlotsSoichiro Hayashi, Bose Corporation - Framingham, MA, USA; Akira Mochimaru, Bose Corporation - Framingham, MA, USA; Paul F. Fidlin, Bose Corporation - Framinham, MA, USA
Previous work presented the radiation characteristics of a horizontally asymmetrical waveguide that utilizes a continuous arc diffraction slot. It showed good coverage control above 1 kHz, as long as the waveguide center line axis angle stays below a certain angle limit. This paper examines the radiation characteristics of an array of horizontally asymmetrical waveguides. Waveguides with different angular variations are developed, and several vertical arrays are constructed consisting of those waveguides. The radiation characteristics of the arrays are measured. Horizontally symmetrical and asymmetrical vertical arrays are compared, and the consistency inside of the coverage and limitations are discussed.
Convention Paper 8865 (Purchase now)

P10-2 Numerical Simulation of Microphone Wind Noise, Part 1: External FlowJuha Backman, Nokia Corporation - Espoo, Finland
This paper discusses the use of the computational fluid dynamics (CFD) for computational analysis of microphone wind noise. The first part of the work, presented in this paper, discusses the behavior of the flow around the microphone. One of the practical questions answered in this work is the well-known difference between “pop noise,” i.e., noise caused by transient flows, and wind noise generated by more stationary flows. It appears that boundary layer separation and related modification of flow field near the boundary is a significant factor in transient flow noise, while vortex shedding, emerging at higher flow velocities, is significant for steady state flow. The paper also discusses the effects of the geometrical shape and surface details on the wind noise.
Convention Paper 8866 (Purchase now)

P10-3 Listener Preferences for Different Headphone Target Response CurvesSean Olive, Harman International - Northridge, CA, USA; Todd Welti, Harman International - Northridge, CA, USA; Elisabeth McMullin, Harman International - Northridge, CA USA
There is little consensus among headphone manufacturers on the preferred headphone target frequency response required to produce optimal sound quality for reproduction of stereo recordings. To explore this topic further we conducted two double-blind listening tests in which trained listeners rated their preferences for eight different headphone target frequency responses reproduced using two different models of headphones. The target curves included the diffuse-field and free-field curves in ISO 11904-2, a modified diffuse-field target recommended by Lorho, the unequalized headphone, and a new target response based on acoustical measurements of a calibrated loudspeaker system in a listening room. For both headphones the new target based on an in-room loudspeaker response was the most preferred target response curve.
Convention Paper 8867 (Purchase now)

P10-4 Optimal Condition of Receiving Transducer in Wireless Power Transfer Based on Ultrasonic Resonance TechnologyWooSub Youm, Electronics and Telecommunications Research Institute (ETRI) - Daejeon, Korea; Gunn Hwang, Electronics and Telecommunications Research Institute (ETRI) - Daejeon, Korea; Sung Q Lee, Electronics and Telecommunications Research Institute (ETRI) - Daejeon, Korea
Recently, wireless power transfer technology has drawn lots of attention because of wire reduction and charging convenience. Previous technologies such as magnetic resonance and induction coupling have drawbacks of short transfer distance and harmfulness to human health. As an alternative, ultrasonic resonance wireless power transfer technology is proposed. A pair of commercial ultrasonic transducer arrays for sensor application is used for wireless power transfer. There are two parameters that have to be decided to maximize the efficiency of power transfer. The first parameter is load resistance that is connected to receiving transducer. It should be matched to the impedance of receiving the transducer at resonance frequency. The second one is the operating frequency of transmitting transducer. It should be matched to the optimal frequency of the receiving transducer. In this paper this optimal load resistance and the frequency of the receiving transducer are analyzed based on circuit theory and verified through experiment.
Convention Paper 8868 (Purchase now)

P10-5 Design of a Headphone Equalizer Control Based on Principal Component AnalysisFelix Fleischmann, Fraunhofer Institute for Integrated Circuits IIS - Erlangen, Germany; Jan Plogsties, Fraunhofer Institute for Integrated Circuits IIS - Erlangen, Germany; Bernhard Neugebauer, Fraunhofer Institute for Integrated Circuits IIS - Erlangen, Germany
Unlike for loudspeakers, the optimal frequency response for headphones is not flat. A perceptually optimal target equalization curve for headphones was identified in a previous study. Moreover, strong variability in the frequency characteristics of 13 popular headphone models was observed. Model-specific equalization filters can be implemented but would require the headphone to be known. For most consumer applications this seems impractical. Principal component analysis was applied to the measured headphone equalization data, followed by a reduction of the degrees of freedom. The remaining error is identified objectively. It can be shown that using only one principal component, the sum of a fixed and a weighted filter curve can replace model-specific equalization.
Convention Paper 8869 (Purchase now)

P10-6 Effect of Elastic Gel Layer on Energy Transfer from the Source to Moving Part of Sound TransducerMinsung Cho, Edinburgh Napier University - Edinburgh, UK; Elena Prokofieva, Edinburgh Napier University - Edinburgh, UK; Mike Barker, Edinburgh Napier University - Edinburgh, UK
The use of porous materials in sound is quite well-known. The materials can be used for absorption of unwanted radiation, for dissipation, and re-distribution of the waves while travelling through the thickness of material and for enhancement of the overall sound and therefore energy transfer within the material. A three layer system comprising of two rigid layers of material with a soft gel middle layer between them was investigated in this research work to establish the effect of the gel material on the system’s energy performance. The role of the gel layer in transferring the energy to the panel was investigated. It was demonstrated by experiments that the gel layer between the top layer and the last layer enhances the performance of the overall construction and also minimizes the mechanical distortion by absorbing its bending waves. This effect enables to extend the radiating frequency of the construction up to high and down to lower frequencies.
Convention Paper 8849 (Purchase now)

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