2004 September, Volume 52 Number 9

CONTENT

PAPERS

Errors in Real-Time Room Acoustics Dereverberation
Panagiotis D. Hatziantoniou and John N. Mourjopoulos   883
While researchers have been studying methods for removing the effects of room acoustics for over 20 years, results are often inconsistent between computer simulations and real applications. This discrepancy has not been formally studied. Errors in measurements of real spaces are significantly higher than expected, even when they are carefully performed. Additionally, when combined with long filters, perceptual artifacts are often worse than the advantages of such systems. High-Q poles used in such filters are very sensitive to listener location and to time-varying acoustic noise present inside the room. By using complex smoothing, which implies a reduction in the degree of room compensation, unpleasant artifacts are greatly reduced.

Development and Validation of a Method for Predicting the Perceived Naturalness of Sounds Subjected to Spectral Distortion
Brian C. J. Moore and Chin-Tuan Tan   900
Having partitioned distortion into linear and nonlinear distortion and having explored the degree to which such distortions degrade the perception of naturalness, the authors now propose a model to explain the perceptual effects of linear distortion, namely, irregularities in the frequency response. Using the data from 168 filtering conditions, a perceptual model based on excitation patterns has been developed to predict subjective judgments. The model is based on the difference between the excitation patterns for undistorted and distorted pink noise. Two validation experiments supported the model.

Interpositional Transfer Function for 3D-Sound Generation
F. P. Freeland, L. W. P. Biscainho, and P. S. R. Diniz   915
In order for head-related transfer functions to gain widespread use in binaural audio applications, there needs to be efficient ways for interpolating among a limited number of reference cases that are quantized in elevation and azimuth without loss of perceived accuracy. A triangular interpolation combined with an auxiliary function, called interpositional transfer function, save more than 40% of the operations required by the traditional bilinear methods. This method was employed in a system that generated moving locations.

Measurement and Application of Equivalent Input Distortion
Wolfgang Klippel   931
Because a loudspeaker can be considered as a single-input, multiple-output transducer, distortion should ideally be measured at multiple spatial locations. This produces a massive collection of data, much of which is redundant. Rather, the author shows that the dominant nonlinearities add distortion to the input signal, which is transferred by a linear system to each point in space. This model leads to a new measurement technique that gives deeper insight into the distortion mechanisms and the influence of the acoustical environment, noise, and parasitic vibrations.

STANDARDS AND INFORMATION DOCUMENTS

AES Standards Committee News   948
Digital audio measurement; storage and handling; digital library and archive systems; acoustics-sound source modeling; loudspeaker measurement; IEEE 1394; audio metadata

FEATURES

25th Conference Report, London   952
Bass Handling in Spatial Reproduction   962
118th Convention, Barcelona, Call for Papers   991

DEPARTMENTS

News of the Sections   968
Sound Track   977
Upcoming Meetings   978
New Products and Developments   979
Available Literature   980
Membership Information   981
Advertiser Internet Directory   982
Sections Contacts Directory   993
AES Conventions and Conferences   1000

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2004 September, Volume 52 Number 9

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