Ocean Acoustics → Interactive

Masking Zone Viewer

Drag the source level slider and watch two zones respond differently. The shutdown zone (160 dB threshold) collapses quickly with attenuation. The communication masking zone barely budges. This is why bubble curtains solve one problem but not the other.

Source Level

Default: 210 dB (typical with basic mitigation). Unmitigated impact: 220 dB.

Jump to Technology

2.5
Shutdown (km)
108
Masking (km)
43x
Ratio

Zone Comparison (not to scale)

Level B Shutdown Zone (160 dB)
Communication Masking Zone (~115 dB)

Why the asymmetry? The shutdown threshold (160 dB SPLrms) is close to the source level, so small reductions in source level produce large reductions in zone radius. The masking threshold (~115 dB) is far below the source, operating in the flat tail of the transmission loss curve where the same source reduction barely changes the distance. This is fundamental physics, not a technology limitation.

This tool uses a simplified cylindrical spreading model (TL = 17.5 · log10(r) + 0.0003r dB/m absorption) for interactive illustration. The study’s quantitative results use the RAM PE parabolic equation solver with real bathymetry and sound speed profiles. Masking threshold: ambient noise ~105 dB (Wenz 1962, moderate shipping/wind, 50–500 Hz) + ~10 dB SNR for reliable detection (Clark et al. 2009) ≈ 115 dB received level. Level B harassment threshold: 160 dB SPLrms per NOAA Technical Guidance (2024).

Study Back to Study Hub Next → Seasonal Risk Map