In This Section
Journal of the AES
2009 December - Volume 57 Number 12
Estimating the Velocity Profile and Acoustical Quantities of a Harmonically Vibrating Loudspeaker Membrane from On-Axis Pressure Data
The velocity profiles of rigid pistons, supported radiators, clamped radiators, Gaussian radiators, and real loudspeaker drivers can be approximated using only a few terms of their Zernike expansions. The computed profile allows for the extrapolation of far-field pressure data, including off-axis behavior without requiring the use of anechoic rooms. The authors explore a method to perform forward and inverse sound pressure computations for circular radiators with nonuniform velocity profiles. Acoustic parameters of a harmonically excited resilient, flat, circular loudspeaker in an infinite baffle can thus be computed.
Spatialized augmented-reality audio systems superimpose virtual sound sources onto sounds from a real acoustic environment. Applications include assistance for visually impaired users, guidance systems, teleconferencing, attention-focusing systems, and electronic games. In the proposed system, acoustically transparent earpieces are used to allow environmental sounds to be heard directly while the virtual reality is created electronically. The results show that the listener can localize virtual sound sources as accurately as when using earphones, which are standard for virtual auditory space presentation, while there is only minor degradation in his ability to localize real sound sources.
With ensembles composed of musicians connected over large distances via the Internet, the issue of sound delay becomes very important. This study explores the effect of delay on tempo change, imprecision, leader–follower strategy, and quality. Eleven pairs of musically experienced subjects clapped a simple complementary rhythmic pattern together for about 15 seconds while the delay was varied from 6 to 68 ms. Acceptable delay thresholds were empirically determined.
A system, called FlexSM, is proposed, which is a unified yet flexible platform for developing, testing, and comparing existing as well as new algorithms for sinusoidal analysis of audio. FlexSM, which is implemented in Matlab, offers a graphical user interface and a report generator to aid system configuration and visual assessment of the results.
Standards and Information Documents
AES Standards Committee News
Audio applications of networks; transfer technologies; digital library and archive systems; forensic audio; loudspeaker modeling and measurement; microphone measurement and characterization
37th Conference Report, Hillerød
127th Convention Report, New York
127th Convention Exhibitors
Class D power amplifiers are rapidly becoming the technology of choice for audio products. Integration of these amplifiers in CMOS (complementary metal oxide semiconductor) designs for portable devices requires careful treatment if audio power output is to be maximized for minimal power consumption, while at the same time ensuring low electromagnetic interference and protection of loudspeakers. Papers from the 37th International Conference dealing with these themes are summarized, showing that effective solutions can be developed.
40th Conference, Tokyo, Call for Papers
Call for Nominations for the Board of Governors
Call for Awards Nominations
Index to Volume 57