Sound Exposure Level (SEL) is a measure of the total acoustic energy over a specific period. It accounts for both the intensity and duration of a noise event, making it a key indicator for assessing the impact of sound on marine life and human health.
Measured in decibels (dB) and expressed in Pa²·s (Pascal-squared seconds)
A longer or louder event = higher SEL
Why SEL Monitoring Is Important in the Maritime Industry
Shipping operations generate continuous and high-intensity underwater noise. Monitoring SEL helps:
Understand and mitigate impacts on marine life
Comply with international environmental regulations
Protect crew and passengers from excessive noise exposure
Improve a company's sustainability and reputation
Types of Noise from Shipping Activities
Noise is generally categorized into two main types:
Impulsive noise
Generated by sonar, cavitation from propellers, pile driving, and dredging
Continuous noise
Produced by engines, hull vibration, and general machinery
These noises vary in intensity and frequency and are emitted by all kinds of vessels including cargo ships, tankers, fishing boats, and recreational craft.
Impact on Marine Ecosystems and Human Health
Underwater noise can:
Disrupt communication and navigation in marine mammals
Cause stress and physical harm
Lead to hearing loss in marine species and humans
Affect reproduction and population distribution of aquatic animals
For humans, chronic exposure to high noise levels on ships can cause hearing damage, stress, sleep disorders, and cardiovascular issues.
Acoustic Wave Sensors
These sensors use acoustic waves to detect physical or chemical changes in the environment—such as pressure, temperature, or gas presence.
Acoustic waves interact with substances or surfaces, and changes in wave behavior (frequency, velocity, etc.) reveal environmental variations.
Surface Acoustic Wave (SAW) Sensors
Ideal for chemical/gas detection
Bulk Acoustic Wave (BAW) Sensors
High-precision readings of pressure or temperature
Love Wave Sensors
Excellent for monitoring changes in liquid environments
How Shipping Professionals Monitor SEL
These tools help assess underwater noise levels during operations and before launching high-impact projects like port construction or offshore wind farms.
Hydrophones and passive acoustic monitoring systems
Real-time data dashboards
Software powered by AI for data analysis and reporting
International standards (such as ISO 6954:2000) for compliance
When to Use SEL Monitoring
During regular shipping operations in busy marine corridors
Before launching construction or dredging projects
When operating near sensitive ecosystems
For compliance audits and environmental assessments
Looking to simplify your environmental compliance?
Let us help you track, analyze, and reduce your acoustic impact.
