Authors:Jensen, Joe; Agerkvist, Finn T.; Harte, James M.
Affiliation:Institute of Acoustic Technology, Technical University of Denmark, Lyngby, Denmark; Centre for Applied Hearing Research (CAHR), Technical University of Denmark, Lyngby, Denmark
Page:91
Balanced-armature-type loudspeakers, predominantly used in hearing aids, are inherently nonlinear devices, as any displacement of the loudspeaker diaphragm inevitably changes the magnetic and electrical characteristics of the loudspeaker. A numerical time-domain model capable of describing these nonlinearities is developed. By simulation it is demonstrated how the output distortion could potentially be reduced significantly through careful design of the mechanical properties of the armature.
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Authors:Behrends, Herwig; von dem Knesebeck, Adrian; Bradinal, Werner; Neumann, Peter; Zölzer, Udo
Affiliation:NXP Semiconductors, Hamburg, Germany; Helmut Schmidt University, University of the Federal Armed Forces, Hamburg, Germany
Page:102
Although FIR filters are usually used to equalize a system, a series of second-order biquad IIR filters has the advantage of lower computational cost and smaller memory. An automatic way of adjusting the IIR parameters makes IIR filters an acceptable alternative. Depending on the way in which the target function was defined, the optimizer provides a stable result. The method is illustrated with subjective listening tests and detailed measurements using practical examples of small loudspeakers in modern consumer products.
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Authors:Cecchi, Stefania; Palestini, Lorenzo; Peretti, Paolo; Romoli, Laura; Piazza, Francesco; Carini, Alberto
Affiliation:DIBET, Università Politecnica delle Marche, Ancona, Italy; DMFI, Università di Urbino, Urbino, Italy
Page:110
A frequency domain, multipoint equalization algorithm can be used to improve sound quality in a variety of spaces ranging from automobiles to home living rooms. The equalizer is designed in the frequency domain. From a set of smoothed impulse responses, suitable frequency prototypes are extracted. Inverse filters are then obtained by frequency deconvolution with regularization or LPC modeling. Compared to single-point equalization, the proposed algorithm proves to be superior in terms of spectral deviation and robustness. Various computational methods have been explored. Then the robustness of multipoint equalization is also evaluated for positions that differ from those used for the equalizer estimation.
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Authors:Blanco-Martin, Elena; Casajús-Quirós, Francisco Javier; Gómez-Alfageme, Juan José; Ortiz-Berenguer, Luis Ignacio
Affiliation:Department of Audiovisual and Communication Engineering, Universidad Politécnica Madrid, Madrid, Spain; Tecnica Department of Signals, Systems and Radiocommunication, Universidad Politécnica Madrid, Madrid, Spain
Page:124
Using real subjects to evaluate a sound system’s ability to accurately reproduce the location of sound events requires significant time, personnel, and preparation. Having a reliable measurement tool that produces the same results as subjective listening tests has high value. Objective measures replace subjective judgments using a tool that contains a psychoacoustic model of the human auditory system. Results with real and virtual signals show that the tool accurately simulates auditory localization for virtual acoustic openings.
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Author:Rumsey, Francis
Page:149
In a world dominated by disposable recorded music, delivered in many cases with only average sound quality, there is an emerging ray of hope for audiophiles. It is in fact a Blu-ray of hope, as the high-definition (HD) successor to the DVD in the video domain is also a capable carrier of multichannel audio in a variety of formats. Not only that, but with fast Internet speeds and higher-capacity “pipes” to the home, the promise of being able to download or stream high-quality surround music is rapidly being realized. So what is going on in the HD consumer audio market? We find a growing market for serious music delivered at high sampling rates and bit depths, along with a business model that enables niche recording companies to sell direct to the consumer, bypassing the middleman entirely. Of particular interest is the evidence that when there is a high-resolution version of an album available, perhaps costing more than the standard version, it can outsell the standard version by a considerable margin.
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