Journal of the Audio Engineering Society

2003 May - Volume 51 Number 5


[feature article] Technical Committees are centers of technical expertise within the AES. Coordinated by the AES Technical Council, the Technical Committees track trends in audio in order to recommend to the Society special papers sessions, workshops, standards, projects, publications, and awards in their fields. In order to facilitate this advisory role of the Technical Council, every two years the chairs of all Technical Committees report to the Technical Council by listing the most current technical and policy matters the committees are aware of. The short reports presented here identify, from the global perspective, current research trends and interests in various technical fields of audio.

The National Radio Systems Committee's testing and evaluation program for in-band onchannel digital audio broadcast systems is described. The results of laboratory and field tests performed during 2001 on iBiquity Digital Corporation's AM-band and FM-band IBOC DAB systems are reported. The conclusions drawn from the laboratory and field test results are also reported, and implications for the future are discussed.

A Low-Cost Intensity Probe

Authors: Raangs, R.; Druyvesteyn, W. F.; De Bree, H. E.

The sound intensity in a sound field can be determinated from two acoustical measurements method, the sound intensity is calculated by means of two spaced microphones. Another method, the p-u method, uses a pressure sensor to measure the sound particle velocity. Using the p-u method, measurements performed with a low-cost intensity probe and a computer soundcard combined with an open-source software show good agreement with results obtained with a p-p probe.

Modal Equalization of Loudspeaker - Room Responses at Low Frequencies

Authors: Mäkivirta, Aki; Antsalo, Poju; Karjalainen, Matti; Välimäki, Vesa

The control of excessively long decays in a listening room with strong low-frequency modes is problematic, expensive, and sometimes impossible with conventional passive means. A systematic methodology is presented to design active modal equalization able to selectively reduce the mode decay rate of a loudspeaker-room system at low frequencies in the vicinity of a sound engineer's listening location. Modal equalization is able to increase the rate of initial sound decay at mode frequencies, and can be used with conventional magnitude equalization to optimize the reproduced sound quality. Two methods of implementing active modal equalization are proposed. The first modifies the primary sound such that the mode decay rates are controlled. The second uses separate secondary radiators and controls the mode decays with additional sound fed into the secondary radiators. Case studies are presented of implementing active modal control according to the first method.

The voice-coil peak displacement Xmax is an important driver parameter for assessing the maximum acoustic output at low frequencies. The existing standard AES2-1984 defines the peak displacement Xmax by measuring harmonic distortion in either voice-coil current or displacement. This freedom of choice gives completely different and controversial results. After a critical review of this performance-based technique, an amendment of this method is suggested. Alternatively, a parameter-based method is developed giving more detailed information about the cause of the distortion, limitations, and defects. The relationship between performance-based and parameter-based methods is discussed, and both techniques are tested with real drivers.

Engineering reports

Industry Evaluation of In-Band On-Channel Digital Audio Broadcast Systems

Standards and Information Documents

AES46-2002 AES standard for network and file transfer of audio - Audio-file transfer and exchange - Radio traffic audio delivery extension to the broadcast WAVE file format

AES Standards Committee News


114th Convention Report, Amsterdam



Technical Council Reports

Technical Committee Reports: Emerging Trends in Technology


News of the Sections

Upcoming Meetings

Advertiser Internet Directory

New Products and Developments

Available Literature

Membership Information

Sections Contacts Directory

AES Conventions and Conferences


114th Convention Papers Insert

Cover & Sustaining Members List

VIP List & Editorial Staff

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