In this paper, environmental parameter estimation for a shallow ocean is addressed by using wideband shipping noise as a source of acoustic energy. Unknown locations of the broadband acoustic sources are estimated simultaneously with the ocean depth using the approximate Conditional Maximum Likelihood Estimator (CMLE). This procedure is tested via computer simulations and applied to the experim...

Incidental sounds produced by Phyllophaga crinita (Burmeister) and Cyclocephala lurida (Bland) (Coleoptera: Scarabaeidae) white grubs were monitored with single- and multiple-sensor acoustic detection systems in turf fields and golf course fairways in Texas. The maximum detection range of an individual acoustic sensor was measured in a greenhouse as approximately the area enclosed in a 26.5-cm-...

A near sea floor, 200 meter vertical acoustic array is being developed as part of a long term sea floor monitoring station to study gas hydrate deposits. This report addresses progress in the development of a vertical seismic array system specifically designed for 3-dimensional mapping of shallow gas hydrate deposits. The time frame covered in this report includes the first half of the second y...

The flight path of an aircraft travelling at constant velocity and constant altitude is described by a set of five motion parameters which can be estimated using a ground-based wide aperture acoustic array. The narrowband motion parameter estimation method, based on the Doppler effect, requires the aircraft to emit an acoustic tone that is often absent in the case of a jet aircraft. The motion ...

During November 1994, broadband acoustic signals were transmitted from a 75-Hz source to a 20-element, 700-m vertical array at approximately 3250 km range in the eastern North Pacific Ocean as part of the acoustic engineering test (AET) of the acoustic thermometry of ocean climate program [Worcester et al., J. Acoust. Soc. Am. 105, 3185-3201 (1999)]. The AET tomography signal can be treated as ...

A sound reproduction system usually consists of several types of loudspeakers to cater to sophisticated applications. The directivity of a loudspeaker is a measure of its efficiency in sending sounds to a particular direction instead of all directions. Demand to control the directivity of a sound reproduction system is gaining momentumwith many new designs of directional loudspeakers, including...

The classical approach for acoustic imaging consists of beamforming, and produces the source distribution of interest convolved with the array point spread function. This convolution smears the image of interest, significantly reducing its effective resolution. Deconvolution methods have been proposed to enhance acoustic images and have produced significant improvements. Other proposals involve...

This paper presents the microfabrication of an acoustic impedance gradient matching layer on a spherically-shaped piezoelectric ultrasonic transducer. The acoustic matching layer can be designed to achieve higher acoustic energy transmission and operating bandwidth. Also included in this paper are a theoretical analysis of the device design and a micromachining technique to produce the novel tr...

Sound visualizations have been an integral part of room acoustics studies for more than a century. As acoustic measurement techniques and knowledge of hearing evolve, acousticians need more intuitive ways to represent increasingly complex data. Microphone array processing now allows accurate measurement of spatio-temporal acoustic properties. However, the multidimensional data can be a challeng...

Preliminary results are presented from an analysis of mid-frequency acoustic transmission data collected at range 550 m during the Shallow Water 2006 Experiment. The acoustic data were collected on a vertical array immediately before, during, and after the passage of a nonlinear internal wave on 18 August, 2006. Using oceanographic data collected at a nearby location, a plane-wave model for the...