Low Frequency Ambient Noise Dynamics and Trends in the Indian Ocean, Cape Leeuwin, Australia

Analysis of ambient noise offshore Cape Leeuwin Australia suggests long-term dynamics may be cyclic.

The nonlinear trend is found to be consistent with trends in oceanographic sea surface temperature, which are thought to drive changes in Antarctic sea ice extent. Assessment of oscillatory dynamics finds causal covariance between ambient noise levels and Indian Ocean sea surface temperature dipoles. Dynamics of annual ambient noise and Antarctic sea ice extent are examined suggesting a phase-locked relationship revealing nonlinear characteristics of the presumed dependence.

Article in Journal of the Acoustical Society of America, 2023

Ambient noise IMF8 (annual period, dB) and Antarctic sea ice extent.
Cape Leeuwin, Australia
Convergent cross mapping of ambient noise and potential drivers

Acoustic Tracking & Monitoring of the Cape Sable Seaside Sparrow

The Cape Sable Seaside Sparrow is an endangered species whose known habitat is located in proximity of Everglades National Park.

The recent advent of self-contained, multi-channel, GPS-time-synchronized acoustic recorders has made passive acoustic localization feasible. We are using Wildlife Acoustics Songmeters in a 4-element acoustic array configuration to monitor and localize the Cape Sable Seaside Sparrow.

Description of the 4-element acoustic array Applied Acoustics, 2017

4-element acoustic array
CSSS song spectrogram Coherent cross-correlation processing app

Acoustic Tracking & Characterization of Tornadoes

Research using sensitive atmospheric infrasound sensors developed at the National Center for Physical Acoustics has demonstrated the ability to track and characterize tornadoes and the associated vortex turbulence aloft over distances of 100 km. Higher frequency analysis finds a quantitative link between the acoustic energy and dominant turbulence-eddy length scales, suggesting a method to remotely monitor the dynamics and strength of the storm.

Infrasonic tornado tracking and characterization:   Journal of the Acoustical Society of America, 135

A 9MB pdf on Tornado Acoustics Presented at the NOAA OneScience Seminar, May 30, 2012.  

GFPE Model of acoustic propagation at 3 Hz
CEPG Tornado Acoustic Spectrum

The Rotary Subwoofer: a controllable infrasound source

Acoustic model and measurements:
  Journal of the Acoustical Society of America, 125(4)

IMS array insonification:
  Journal of the Acoustical Society of America, 125(4)

Model for source radiation:   Python code.

Building resonances when driven by the source:   Python Code.

Rotary Speaker, Acoustic Spectrum, Schematic Diagram

Bubble Dynamics and Acoustic Radiation of Plunging Waves

Collective Bubble Oscillations as a Component of Surf Infrasound
  Journal of the Acoustical Society of America, 123(5)

Beamforming from a monolithic piezoelectric composite

Active-Control of Acoustic Beamforming with an Electrode Array on a Piezoelectric Rubber Composite
  Journal of the Acoustical Society of America, 93(6)