Saturday, August 12, 2006

Digital Broadcasters|AES Seoul Papers (12)

The 29th AES Conference, "Audio for Mobile and Handheld Devices", all digital, September 2 to 4, 2006 Seoul National, lUniversity Campus

Digital Audio Presentations - Part 12

Stereo Widening For Loudspeakers in Digital Mobile Devices

Invited Speakers:

Pauli Minnaar and Jan Abildgaard Pedersen, AM3D, Denmark

A new cross-talk cancellation system is proposed for processing normal digital stereo signals to be played back through a pair of very closely-spaced loudspeakers, such as in a mobile phone. The goal of the proposed system is to substantially widen the stereo image while maintaining the timbre of the original stereo material. Several digital implementations of the system are shown and the advantages over traditional cross-talk cancellation systems are discussed.

In Digital, Evaluation of Iterative Matching for Scalable Wavetable Synthesis

Guest Speakers:

Simon Wun, Institute for Infocomm Research, Singapore,

Andrew Horner, Hong Kong University of Science and Technology, Hong Kong

Wavetable synthesis of musical instrument tones has attracted some interest in its application in the generation of polyphonic ringtones on mobile phones. Recent work on digital wavetable synthesis assumes that a constant number of wavetables are used throughout the duration of a tone. A scalable approach would dynamically allocate wavetables to simultaneous voices to allow more polyphony and improve the sound quality. Iterative wavetable matching finds the basis spectra one by one over several iterations, and offers real-time control of the number of wavetables, supporting scalability. This paper describes and evaluates several iterative methods. Matching results for a range of instruments show that, on average, iterative local search can find matches with errors within 0.5\% of near-optimal non-iterative solutions. Iterative local search only rarely gets stuck on bad local optima.

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