ASA 124th Meeting New Orleans 1992 October

4pUW14. A scheme for measuring environmental parameters from the ambient acoustic field with a vertical array of hydrophones.

George B. Smith

Naval Res. Lab., Code 244, Stennis Space Center, MS 39529-5004

Charles L. Byrne

Univ. of Lowell, Lowell, MA 01854

Howard A. Chandler

Naval Res. Lab., Stennis Space Center, MS 39529-5004

High-resolution matched-field processing requires rather exact specification of the environment through which the acoustic field has propagated in order to perform satisfactorily. Measuring the environment to this level of precision presents a severe challenge to the implementation of high-resolution matched-field algorithms. Hence, techniques that can extract environmental information from the ambient acoustic field make a desirable complement to the high-resolution source localization techniques that require such a well-specified environment. In this work, a high-resolution estimator function that matches ambient acoustic field data from a vertical array of hydrophones to trial environments from a normal mode environmental model is used to estimate the parameters of the environment through which the acoustic energy passed. Shallow-water simulations are used to explore the response of the estimator as a function of several environmental parameters. The general conclusion is that unique estimates for these parameters exist, and the estimator developed here is sensitive to small changes in these parameters. [This work was supported by the Office of Naval Research, Program Element 61153N, with technical management provided by the Naval Research Laboratory, Stennis Space Center, MS.]

Standards Committee S1 on Acoustics. Working group chairs will report on their preparation of standards on methods of measurement and testing, and terminology, in physical acoustics, electroacoustics, sonics, ultrasonics, and underwater sound. Work in progress includes measurement of noise sources, noise dosimeters, integrating sound-level meters, and revision and extension of sound level meter specifications. Open discussion of committee reports is encouraged. The international activities in ISO/TC 43 Acoustics, and IEC/TC 29 Electroacoustics, will also be discussed. The Chairs of the respective U.S. Technical Advisory Groups for ISO/TC 43 (H. E. von Gierke), and IEC/TC 29 (V. Nedzelnitsky), will report on current activities of these Technical Committees. Reports will be given on preparations for the next meetings of ISO/TC 43 (in Oslo, Norway, from 31 May--4 June 1993), and of IEC/TC 29 (in Oslo, Norway, from 24--28 May 1993).

Standards Committee S3 on Bioacoustics. The current status of standards under preparation will be discussed. In addition to those topics of interest, including hearing conservation, noise, dosimeters, hearing aids, etc., consideration will be given to new standards which might be needed over the next few years. Open discussion of committee reports is encouraged.The international activities in ISO/TC 43 Acoustics, and IEC/TC 29 Electroacoustics, and ISO/TC 108/SC4 Human Exposure to Mechanical Vibration and Shock, will also be discussed. The Chairs of the U.S. Technical Advisory Groups for ISO/TC 43 (H. E. von Gierke), and IEC/TC 29 (V. Nedzelnitsky), will report on current activities of these Technical Committees and Subcommittees. Reports will be given on preparations for the next meetings of ISO/TC 43 (in Oslo, Norway, from 31 May--4 June 1993), and of IEC/TC 29 (in Oslo, Norway, from 24--28 May 1993). ISO/TC 108/SC4 will next meet in London, U.K., from 29 March to 1 April 1993.