EECS Main > Events

Event Details

James D. (JJ) Johnston

4:00 p.m
October 21, 2009
Tech LR2

James D. (J.J.) Johnston, Neural Audio
"Beyond MP3: Multichannel Audio
Home Theatre Versus Cinema"
ABSTRACT
MP3, MPEG-AAC, and other perceptual audio coders exploit the nature of the human auditory system in order to reduce the data rate necessary to transmit an audio signal. In an analogous fashion, a soundfield present in a real or imagined venue can be examined to see what parts of the enormous information (thousands of channels worth of data in 1 meter diameter sphere) present in a soundfield are actually perceptible to the human listener. Using this knowledge, it is possible to “overwrite” the sensation of being in a small room with that of being in a larger room (for instance, simulating an aircraft hangar inside of a home theatre space). It is not, however,generally possible to create the sensation of a smaller space inside of a larger space. In addition, the differential time delays and angular positions of loudspeakers in a larger (cinema) space vs. a smaller (home theatre) space create entirely different requirements for capture, production, and synthesis of a desired sensation. This talk will discuss, at a conceptual level, what kinds of acoustic cues are present in a space, what kinds of cues are captured by the auditory system, and how one can use this knowledge to “transmit” a desired sensation of space and direction via multichannel reproduction in the home theatre. Cinema production techniques will be briefly discussed, and the reason for their necessarily limited use of multichannel audio effects explained.

BIO
JJ is presently the Chief Scientist for DTS, Inc, working from Kirkland, Washington. DTS provides the high-quality audio system for BlueRay disc, and is an industry leader in audio coding, codec preprocessing, multichannel audio, loudness control, and other advanced signal processing algorithms for audio.

His current interests include loudspeaker pattern analysis and control, loudness modelling, room simulation, stereo image control and analysis, filter design, speech coding, audio and speech testing methodology and execution, and implementation concerns in audio processing.

He is the primary inventor and architect for a variety of signal processing algorithms related to room correction, loudness processing, perceptual modelling of audio, audio coding, audio soundfield perception and presentation, and standards and ancillary mathematics and science related to audio issues.

His prior contributions include MPEG-2 AAC (Advanced Audio Coding) standard, developed in collaboration with Fraunhofer IIS and other experts in the field of audio compression, MPEG-2 AAC is a reworking of the original AT&T Perceptual Audio Coder (PAC), done with Anibal Ferriera, co-invention and standardization of the well-known "MP3" algorithm, a variety of loudness estimation and control methods, automatic speaker and room correction systems, room and acoustic simulators, and invention of a perceptual soundfield reconstruction system to capture the "sound" of an actual performance venue and reconstruct the perceptual cues of the venue in a fashion that can be conveyed in a small (presently 5) number of conventional, independent audio channels multichannel audio presentation, and audio coding (bitrate reduction).

Awards and Societies

In 2006, he was awarded the J. L. Flanagan Signal Processing Field Award from the IEEE Signal Processing Society for his work on creation and standardization of perceptual audio coding.

In 1997, JJ was elected a Fellow of the Audio Engineering Society for his work on perceptual coding of audio.

He became a Senior Member of the IEEE, and recieved an AT&T Technology Medal and AT&T Standards Award in 1998.

In February 2001, he recieved a New Jersey Inventor of the Year award for his contributions to MP3 and audio coding in general.

He was elected a Fellow of the IEEE in 2002.
Hosted by Thrasos Pappas.
Northwestern University Robert R. McCormick School of Engineering and Applied Science Electrical Engineering and Computer Science Department