The application of advanced digital-processing techniques has great potential for systems that transmit voice or utilize information coded in the form of speech. The report employs a digital process that offers a new approach for general use in speech synthesis, and is an application of homomorphic methods to the problem of correcting the distorted speech of talkers in pressurized helium-oxygen atmospheres. The vocal-tract impulse response of such speech was extracted by the homomorphic deconvolution technique, and its frequency components were moved downward in frequency according to correction formulas given in a study by Gerstman (1966). Both linear and nonlinear frequency corrections were used. Speech samples taken at 800-foot pressure depth in a 96 percent helium, 4 percent oxygen atmosphere were processed in this way, using a digital simulation of Oppenheim's (1969) analysis-synthesis system. Results indicate considerable promise for the technique as a tool for further study of helium speech, and perhaps as a future on-line translation method. (Author).

Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Advances in Electronics and Electron Physics

Underwater Research is primarily a review of problems in underwater viewing and hearing and acoustics. The chapters in this book are papers collated from the symposia of the Underwater Association. This book explores the need for the further study of the physiological and psychological reactions of divers. The book also concludes that diving is still the best way in studying the benthic ecology and sunken wrecks and cities. The text is divided into 25 detailed chapters. Most of the topics in the text address the common problems encountered by divers such as in hearing and viewing. Specifically, problems in diver communication, depth estimation, color distinction are some of the topics covered. Other chapters deal with the psychological reactions such as anxiety, narcosis, and visual attention. Also, some chapters tackle solutions and experiments for the improvement of diving techniques and equipment. This reference is helpful to divers, students, and scientists involved in marine and environmental science.