An understanding of how man created noise affects marine species in the country.

2. Cdr (Dr) Arnab Das

5. Menu
Ambient Noise
Anthropogenic Noise
Radiated Noise
Marine Species Hearing
Conclusion

7. Classification

8. Ambient Noise in the Sea

9. Classification

10. Ambient Noise Trend

12. Anthropogenic Noise
Sonar Transmissions
Oil Exploration
Industrial Activities
Explosions
Radiated Noise of Marine Vessels
Acoustic High Power
Transmission.

13. Sonar Transmissions
Military Sonar
SURTASS
Towed Array Sonar
Hull Mounted Sonar
Non-Military
Echo Sounders
Side Scan Sonar
Sub-bottom Profilers

14. Sonar Transmission

15. Sonar Transmissions
Mid-Frequency Range
Limitation of the Transducer size
Higher attenuation Levels
Localized Impact
High Intensity Sound
230 dB re 1µPa @ 1m
Instant Impact

16. Oil Exploration
Seismic Exploration
Finding Reserves of Underwater
Oil
Uses High Intensity Sound
Arrays of Air Gun
Releases Specified Air at High
Pressure
Sound Pressure due to Contraction

17. Oil Exploration

18. Industrial Activities
Dredging
Pile Driving
Underwater Construction
Wind Mills
Power Plants
Canal Lock Operations

19. Industrial Activities

20. Some Comparisons

21. Explosions
Ship Shock Test
To evaluate ability of Ship to
withstand Shock
Chemical Explosion
300-4000 explosions per month
reported in North Pacific in the 1960
Used for removal of Undersea
Structures and Construction

22. Underwater Explosion

23. Explosions
Nuclear Explosion
French test as late as 1995-1996
CTBT does prevent such tests in
future however the precise impact
on Marine Life yet to be ascertained
Weapon Tests
Torpedo firings
Tests for Naval Weapon Systems

24. Radiated Noise
Ship Generated Noise
Propeller Noise
Machinery Noise
Hydrodynamic Noise
Radiated Noise Spectrum
Narrowband Discrete Tonals
Broadband Noise due to Cavitation

25. Radiated Noise

26. Radiated Noise
Low-Frequency Sound
10 – 500 Hz
Undergoes minimal Attenuation
Propagates to a large distance
Distant Shipping
Major contributor to Ambient
Increased Significantly in the last
30 years

28. Radiated Noise
Single Ubiquitous Noise Source
Well Spread out
Low frequency
Minimal Attenuation
Economic Factor
Only likely to rise
India Emerging as a major ship-
building destination

29. Ambient Noise

30. Shipping the World Over

32. Machinery Noise

33. Propeller Cavitation

34. Propeller Cavitation

35. CPP Ships

36. Some Comparisons

37. What Has Changed?

38. Some Comparisons

40. Frequency Response

41. Hearing Loss-Baleen Whale
Estimated reduction in baleen whale communication range from (left) prior to the
advent of commercial shipping to (right) the expected ranges today. Figure courtesy
of C W Clark, Cornell University

42. Fish Hearing

43. Radiated Noise Spectrum
Underwater radiated noise specification at 11 knots free-running for all
vessels used in fisheries research

45. Conclusion
Urgent steps required
Awareness.
Actionable Inputs.
Research efforts to understand our
waters.
Challenges of regulatory
framework.