2001 April, Vol 49 Number 4

CONTENT

PAPERS

Extracting Room Reverberation Time from Speech Using Artificial Neural Networks
T. J. Cox, F. Li, and P. Darlington   219

A novel method to extract reverberation time from reverberated speech utterances that are limited to pronounced digits is presented. The reverberation times considered are wide band, within the frequency range of speech utterances. A multilayer feed forward neural network is trained on speech examples with known reverberation times generated by a room simulator. The trained neural networks are able to extract room reverberation times from speech signals picked up in the room to an accuracy of 0.1 seconds. This is an alternative to traditional measurement methods and facilitates occupied measurement of room reverberation times.

Introduction to Head-Related Transfer Functions (HRTFs): Representations of HRTFs in Time, Frequency, and Space
Corey I. Cheng and Gregory H. Wakefield   231

This tutorial introduces head-related transfer functions (HRTFs) and describes their role in the synthesis of spatial sound over headphones. HRTFs are defined and their importance in clarifying free-field sound's spatial location clues is shown. Also included are measurement methods and applications to spatialized sound synthesis. Different analytic and signal processing techniques are highlighted by comparing and contrasting representations of HRTFs in time, frequency, and spatial domains.

Perceptual Wavetable Matching for Synthesis of Musical Instrument Tones
Cheuk-Wai Wun and Andrew Horner   250

Until recently multiple wavetable synthesis has used a simple relative spectral error formula to measure how accurately the synthetic spectrum matches an original spectrum. A modified error formula takes into account human auditory masking characteristics. It is an improved measure of the perceived quality of the matched spectrum. Listening tests indicate that the perceptual error formula slightly outperforms previous matching methods, especially for instrument tones having several masked partials.

ENGINEERING REPORTS

Signal Mixing for a 5.1-Channel Surround Sound System--Analysis and Experiment
Xie Bosun   263

A new signal mixing method for 5.1-channel surround sound is proposed in which the lateral signal becomes stabilized. This method claims a stable 360o sound image within a frequency range up to 800 Hz. It is proposed that the mixing method from the earlier pairwise mixing technique be used to recreate a stable front image while the new mixing method be used to create stable lateral and rear images. The method employed is dependent upon which sound image is optimal for presentation to the listener.

STANDARDS AND INFORMATION DOCUMENTS

AES Standards Committee News   275
Audio metadata; listening tests; intelligibility

Call for Comment on DRAFT AES31-1-xxxx, AES standard for network file transfer of audio -- Audio-file transfer and exchange -- Part 1: Disk format   275

Call for Comment on DRAFT REVISED AES26-xxxx, Second posting of DRAFT REVISED AES recommended practice for professional audio interconnection -- Conservation of the polarity of audio signals   276

Call for Comment on DRAFT REVISED AES10-xxxx, AES recommended practice for di gital audio engineering -- Serial Mutichannel Audio Digital Interface (MADI)   276

Call for Comment on DRAFT AES28-1997 Amendment-1-xxxx to AES standard for audio preservation and restoration -- Method for estimating life expectancy of compact discs (CD-ROM), based on effects of temperature and relative humidity   276

FEATURES

19th Conference Preview, Bavaria, Germany   282
     Calendar   284
     Program   286
     Registration Form   294

Updates to Review of Society's Sustaining Members   296

DEPARTMENTS

Review of Acoustical Patents   279

News of the Sections   297

Upcoming Meetings   301

Sound Track   302

Available Literature   303

New Products and Developments   304

Membership Information   306

Advertiser Internet Directory   308

Sections Contacts Directory   314

AES Conventions and Conferences   320

FPO For the cover:

2001 April, Vol 49 Number 4

spine: 2001 April, Vol 49 Number 4