• Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Journal of the Acoustical Society of America

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

Oct 2008

Volume 124, Issue 4, pp. i-EL269

Return to All Sections
back to top
RSS Feeds

Methods for determining infrasound phase velocity direction with an array of line sensors

Kristoffer T. Walker, Mark A. Zumberge, Michael A. H. Hedlin, and Peter M. Shearer

J. Acoust. Soc. Am. Volume 124, Issue 4, pp. 2090-2099 (2008); (10 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Infrasound arrays typically consist of several microbarometers separated by distances that provide predictable signal time separations, forming the basis for processing techniques that estimate the phase velocity direction. The directional resolution depends on the noise level and is proportional to the number of these point sensors; additional sensors help attenuate noise and improve direction resolution. An alternative approach is to form an array of directional line sensors, each of which emulates a line of many microphones that instantaneously integrate pressure change. The instrument response is a function of the orientation of the line with respect to the signal wavefront. Real data recorded at the Piñon Flat Observatory in southern California and synthetic data show that this spectral property can be exploited with multiple line sensors to determine the phase velocity direction with a precision comparable to a larger aperture array of microbarometers. Three types of instrument-response-dependent beamforming and an array deconvolution technique are evaluated. The results imply that an array of five radial line sensors, with equal azimuthal separation and an aperture that depends on the frequency band of interest, provides directional resolution while requiring less space compared to an equally effective array of five microbarometers with rosette wind filters.
Show PACS
43.60.Fg Acoustic array systems and processing, beam-forming
43.28.Dm Infrasound and acoustic-gravity waves
43.58.Ta Computers and computer programs in acoustics
43.60.Qv Signal processing instrumentation, integrated systems, smart transducers, devices and architectures, displays and interfaces for acoustic systems

Performance analysis of the Ormia ochracea’s coupled ears

Murat Akcakaya and Arye Nehorai

J. Acoust. Soc. Am. Volume 124, Issue 4, pp. 2100-2105 (2008); (6 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The Ormia ochracea is able to locate a cricket’s mating call despite the small distance between its ears compared with the wavelength. This phenomenon has been explained by the mechanical coupling between the ears. In this paper, it is first shown that the coupling enhances the differences in times of arrival and frequency responses of the ears to the incoming source signals. Then, the accuracy of estimating directions of arrival (DOAs) by the O. ochracea is analyzed by computing the Cramér–Rao bound (CRB). The differential equations of the mechanical model are rewritten in state space and its frequency response is calculated. Using the spectral properties of the system, the CRB for multiple stochastic sources with unknown directions and spectra is asymptotically computed. Numerical examples compare the CRB for the coupled and the uncoupled cases, illustrating the effect of the coupling on reducing the errors in estimating the DOAs.
Show PACS
43.60.Jn Source localization and parameter estimation
43.80.Lb Sound reception by animals: anatomy, physiology, auditory capacities, processing
Return to All Sections
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close