|1998 July/August, VOLUME 46 NUMBER 7|
Study of a Fast Method to Calculate Inverse Filters
Hideki Irisawa, Shoji Shimada, Haruhide Hokari, and Shinichi Hosoya 611
In some digital systems it is important to calculate quickly an inverse filter that has a large number of taps. One fast method uses conjugate gradients in the frequency domain. In this paper, a fast method is proposed which calculates only the linear convolution in conjugate gradients by FFT. This proposed method has shown a residual error that is comparable to the Levinson algorithm, but is quicker.
Analytic Derivation of Audio PWM Signals and Spectra
Andreas C. Floros and John N. Mourjopoulos 621
The authors have presented a method that directly maps any arbitrary audio PCM sample value into PWM pulse transition intervals, thereby producing an analytic description of the PWM data stream. The exact spectrum of the PWM signal can also be derived analytically from the PCM audio date. It is claimed that this proposed method has significant advantages over previous methods used for the analysis of PWM conversion artifacts, since it can allow the implementation of efficient compensating strategies for the reduction of the PWM conversion artifacts.
Signal Convolution of Recorded Free-Field Gunshot Sounds
Bruce E. Koenig, Shawn M. Hoffman, Hirotaka Nakasone, and Steven D. Beck 634
Gunshot sounds of criminal events are often recorded because of the large number of electronic surveillance and recorder systems. Several gunshot sources and electonic transmission systems were examined, as well as some recording systems, to determine the system's ability to identify the types of gunshots by electronic means, with some interesting results.
Subtractive Dither for Internet Audio
Ben Denckla 653
Internet audio files popularly use 8-bit word length and low sampling rates. The author proposes a subtractive dithering scheme that is well suited to these formats as well as to the widely available 16-bit playback hardware. A method of automatic detection of these uniquely encoded files is included in the system.
STANDARDS AND INFORMATION DOCUMENTS
AES Standards Committee News 657
Sab Francisco meetings; IEEE 1394; loudspeakers; connectors
105th Convention Preview, San Francisco 666
Exhibit Previews 678
15th International Conference, Snekkersten, Copenhagen, Announcement
International Sections Directory Updates
106th Convention, Munich, Germany, Call for Papers
News of the Sections 704
Sound Track 707
Available Literature 708
Upcoming Meetings 708
Membership Information 711
Sections Contacts Directory 715
AES Conventions and Conferences 720