Journal of the Audio Engineering Society

2002 December - Volume 50 Number 12

Papers


Moving Digital Audio: Part 1

Authors: Staff, AES

Not available.

Previous work on matching musical instrument tones in wavetable synthesis used combinatorial selection to pick the basis spectra that best match target spectra from the original tone. An iterative method is proposed that divides the selection process over several levels. The results show that the iterative method is about as effective as the original method (within 3.5%) and more efficient.

An experimental investigation into cooperation phenomena is presented, which in this case can be described as the contribution of energy from a random signal to the energy of a periodic signal under certain conditions. Previously cooperation phenomena have been described mainly from a theoretical point of view. However, well-known practical examples exist. For the present experiment a loudspeaker was used that had a slightly rubbing voice coil subjected simultaneously to excitation from a random signal and from a periodic signal. Test results clearly show the influence of cooperation on both the random and the periodic signals. The random signal acquires additional "agility," allowing some of its energy to be transferred to the periodic signal. Experimental results are compared with theoretical analysis based on limit cycles and Van der Pol's oscillators. The application of limit cycles is then extended to friction-induced phenomena. The subject matter is of general interest in the dynamics of nonlinear systems and of more specific interest in the behavior and testing of loudspeakers.

An all-pass crossover is described which is specially suited to realization using a passive high-pass channel that incorporates the closed-back driver. Although the responses of the low-pass and high-pass channels are asymmetrical, it possesses many of the desirable properties of the Linkwitz-Riley crossover. The passive realization minimizes component count, requiring no impedance correction for the high-pass driver.

Frequency-Zooming ARMA Modeling of Resonant and Reverberant Systems

Authors: Karjalainen, Matti; Esquef, Paulo A. A.; Antsalo, Poju; Mäkivirta, Aki; Välimäki, Vesa

Discrete-time analysis and modeling of reverberant and resonating systems has many applications in audio and acoustics. The methodology of ARMA modeling by pole-zero filters for measured impulse responses was investigated. In addition to an overview of the standard AR and ARMA techniques, a spectral zooming technique is proposed, which is useful for resolving very closely positioned modes and high-density modal clusters. Application cases related to the analysis and modeling of room responses, loudspeaker room equalization, and the estimation of parameters for musical instrument modeling are studied.

Engineering reports


Iterative Combinatorial Basis Spectra in Wavetable Matching

Standards and Information Documents


AES Standards Committee News

Features


Moving Digital Audio, Part 1

2002/2003 AES International Sections Directory

Education News

Call for Nominations for Board of Governors

Call for Awards Nominations

11th Tokyo Regional Convention, Call for Papers

115th Convention, New York, Call for Papers

114th Convention, Amsterdam, Call for Workshops Participants

Bylaws: Audio Engineering Society, Inc.

Index to Volume 50

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