Modulation of high frequency noise by engine tones of small boats

Pollara, Alexander; Sutin, Alexander; Salloum, Hady

doi:10.1121/1.4991345

Cited by 18 publications

(2 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Among the various engine-related parameters, only the cylinder firing rate CFR could be well estimated at different pitches from the differences in adjacent harmonic frequencies since the fundamental CFR component was not detected. Under normal conditions, the engine firing rate EFR can be estimated to be the strongest harmonic component of CFR, whose order number is the number of cylinders in the engine [9,63,64]. However, in this analysis, EFR could not be correctly estimated for this ship since the corresponding eighth harmonic was not the strongest tonal harmonic of CFR.…”

Section: Engine-related Parametersmentioning

confidence: 91%

Underwater Sound Characteristics of a Ship with Controllable Pitch Propeller

Zhu

Gaggero

Makris

et al. 2022

JMSE

View full text Add to dashboard Cite

The time-dependent spectral characteristics of underwater sound radiated by an oceanic vessel have complex dependencies on ship machinery, propeller dynamics, and the hydrodynamics of the ship exhaust and motion, as well as onboard activities. Here, the underwater sound radiated by a ship equipped with a controllable pitch propeller (CPP) is analyzed and quantified via its (i) power spectral density for signal energetics, (ii) temporal coherence for machinery tonal sound, and (iii) spectral coherence for propeller amplitude-modulated cavitation noise. Frequency-modulated (FM) tonal signals are also characterized in terms of their frequency variations. These characteristics are compared for different propeller pitch ratios, ranging from 20% to 82% at a fixed number of propeller revolutions per minute (RPM). The efficacy and robustness of ship parameter estimation at different pitches are discussed. Finally, an analysis of one special measurement is provided: propeller pitch and RPM over the duration of the measurement when the ship changes speed. The 50% pitch was found to be a crucial point for this ship, around which the tonal characteristics of its underwater radiated sound attain their peak values while broadband sound and associated spectral coherences are at a minimum. The findings here elucidate the effects of pitch variation on underwater sound radiated by ships with controllable pitch propellers and has applications in ship design and underwater noise mitigation.

show abstract

Section: Engine-related Parametersmentioning

confidence: 91%

Underwater Sound Characteristics of a Ship with Controllable Pitch Propeller

Zhu

Gaggero

Makris

et al. 2022

JMSE

View full text Add to dashboard Cite

show abstract

“…Here, we demonstrate that simultaneous application of the three techniques: MMSC for machinery tonal characterization, CSC for propeller rotation signature characterization, and mean PSD for ship energetics; applied to beamformed pressure-time series data, can efficiently and simultaneously detect and distinguish underwater sound from multiple engine-powered vehicles at varying bearings and ranges over continental shelf regions, effective even in the presence of other natural and man-made sound sources. In contrast, previous approaches and analyses have primarily focused on a single aspect of ship sound and for a specific type of ship, such as the propeller rotation signature of small boats [37,47] or a single cargo ship [2].…”

Section: Introductionmentioning

confidence: 99%

Long-Range Automatic Detection, Acoustic Signature Characterization and Bearing-Time Estimation of Multiple Ships with Coherent Hydrophone Array

et al. 2020

View full text Add to dashboard Cite

Three approaches for instantaneous wide-area analysis of ship-radiated underwater sound, each focusing on a different aspect of that sound, received on a large-aperture densely-sampled coherent hydrophone array have been developed. (i) Ship’s narrowband machinery tonal sound is analyzed via temporal coherence using Mean Magnitude-Squared Coherence (MMSC) calculations. (ii) Ship’s broadband amplitude-modulated cavitation noise is examined using Cyclic Spectral Coherence (CSC) analysis that provides estimates for propeller blade pass rotation frequency, shaft rotation frequency, and hence the number of propeller blades. (iii) Mean power spectral densities (PSD) averaged across broad bandwidths are calculated in order to detect acoustically energetic ships. Each of these techniques are applied after beamforming of the received acoustic signals on a coherent hydrophone array, leading to significantly enhanced signal-to-noise ratios for simultaneous detection, bearing-time estimation and acoustic signature characterization of multiple ships over continental-shelf scale regions. The approaches are illustrated with underwater recordings of a 160-element coherent hydrophone array for six ocean vessels, that are located at a variety of bearings and ranges out to 200 km from the array, in the Norwegian Sea in February 2014. The CSC approach is shown to also be useful for automatic detection and bearing-time estimation of repetitive marine mammal vocalizations, providing estimates for inter-pulse-train and inter-pulse intervals from CSC spectra cyclic fundamental and first recurring peak frequencies respectively.

show abstract