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The reduced noise pollution during the novel coronavirus disease (COVID-19) pandemic made the birds and the bees and other terrestrial creatures flourished; and in the underwater world, too, anthrophony (human-made sounds) reduced substantially for long months in 2020. Scientists are now trying to understand the impact of these quiet months on the marine ecosystem.


GS-III: Environment and Ecology (Environmental Pollution & Degradation, Conservation of Ecology and Environment)

Dimensions of the Article:

  1. Understanding Ocean Noise / Acoustics
  2. The International Quiet Ocean Experiment (IQOE)
  3. What is Hydrophone?

Understanding Ocean Noise / Acoustics

The International Quiet Ocean Experiment (IQOE) has identified a network of over 200 non-military hydrophones (underwater microphones) in oceans across the world.

The three broad components of oceanic acoustics that are being studied are are:

  1. Geophony: Sounds created by non-biological natural events like earthquakes, waves and bubbling.
  2. Biophony: Sounds created by the ocean’s living creatures.
  3. Anthrophony: Sounds created by human beings (a large portion of which is shipping noise).
  • According to ‘the Soundscape of the Anthropocene Ocean report’ published in Science Journal in 2021, geophony and biophony dominated the soundscape of oceans before the industrial era.
  • In the short-term anthrophony masks the auditory signal processing by marine animals, weakening their ability to forage for food, escape a predator or attract a mate. In the long run, it can thin out the population of some underwater species.
  • The oceans of the current geological era (Anthropocene era – when human-made disruptions largely influence the environment) are noisier than the pre-industrial times.
  • During the first few days of the pandemic, ocean sound monitors at several places recorded a decibel (dB) drop.
  • The hydrophones at the Endeavour node of Canada’s Neptune Ocean Observatory showed an average decrease of 1.5 dB in year-over-year mean weekly noise power spectral density at 100 hertz.

The International Quiet Ocean Experiment (IQOE)

  • The International Quiet Ocean Experiment (IQOE) is an international scientific program to promote research, observations, and modelling to improve understanding of ocean soundscapes and effects of sound on marine organisms.
  • IQOE is developing methods to make ocean acoustic data more comparable. These data will be compiled into a global dataset to establish trends in ocean sound and look for effects of the Covid-19 pandemic on ocean sound.
  • The IQOE has identified a network of over 200 non-military hydrophones (underwater microphones) in oceans across the world.

What is Hydrophone?

  • Just as a microphone collects sound in the air, a hydrophone detects acoustic signals under the water.
  • Most hydrophones are based on a special property of certain ceramics that produces a small electrical current when subjected to changes in underwater pressure.
  • When submerged in the ocean, a ceramic hydrophone produces small-voltage signals over a wide range of frequencies as it is exposed to underwater sounds emanating from any direction.
  • By amplifying and recording these electrical signals, hydrophones measure ocean sounds with great precision.

-Source: Down to Earth Magazine

May 2024