How does underwater noise affect dolphins and whales?

In one line

The rule

Noise pollution is the presence of excessive or harmful levels of sound in the environment that can disrupt the life and health of living beings, including animals like dolphins and whales.

Let's understand it simply

Imagine you are in a busy market during Diwali. People are shouting, crackers are bursting, and you can barely hear your friend next to you. Now, think about living in that noise all the time. For dolphins and whales, the ocean is usually a quiet place. They use sound to talk, find food, and even "see" with their ears (this is called echolocation — sending out sounds and listening for echoes). But when ships, oil drills, or underwater explosions make loud noises, it’s like Diwali in the sea all day. Dolphins and whales get confused, scared, and sometimes cannot find their family or food.

How it works

1. Ships, submarines, and oil drilling make loud underwater noises.
2. These sounds travel very far in water — much farther than on land.
3. Dolphins and whales use sound to talk, hunt, and travel.
4. Loud noises block or cover up their sounds, like someone shouting over your voice.
5. They can’t hear each other, get lost, or miss prey.
6. Sometimes, sudden loud noises can even hurt their ears or brains.

The story behind it

Scientists first noticed that whales and dolphins were acting strange near busy shipping lanes and oil drilling sites. In the 1970s and 1980s, some whales were found stranded on beaches after loud underwater explosions or navy sonar tests. Researchers studied these events and found a clear link: underwater noise was disturbing these animals. One famous case was when a group of whales washed up on the shore after a navy sonar test in the Bahamas in 2000. This made people realize how serious underwater noise pollution is.

Where you see it in real life

• Large ships passing through the sea → Their engines and propellers make constant low rumbles → Whales and dolphins can’t hear each other well.
• Oil and gas drilling → Machines called air guns blast sound into the seabed → The noise travels for miles and disturbs animals.
• Navy sonar tests → Powerful sound waves are sent to find submarines → These can confuse or even injure dolphins and whales.
• Underwater construction (like bridges or wind farms) → Pile driving and drilling make loud bangs → Animals nearby get scared or swim away.
• Fishing boats using echo sounders → These send out pings to find fish → Too many pings can bother dolphins and whales.
• Tourist boats chasing dolphins → The noise from engines and people shouting can stress the animals.

Why it matters

• Communication: Dolphins and whales "talk" using clicks, whistles, and songs. Noise pollution makes it hard for them to send or hear these sounds.
• Finding food: They use echolocation to hunt. Loud noise can block the echoes, so they miss prey or get confused.
• Navigation: Some whales travel thousands of kilometers. Noise can make them lose their way or get stranded.
• Health: Sudden loud sounds can damage their hearing or even cause bleeding in their brains.
• Breeding and raising young: Noise can stress mothers and calves, making it harder for babies to survive.

Worked example

Let’s imagine a blue whale trying to call its friend 100 km away.

Given: Whale song can travel 100 km in quiet water
Step 1: Ship noise enters the area
Step 2: Ship noise is louder than the whale song
Step 3: Friend whale cannot hear the call
Step 4: Whales cannot meet or help each other

Common mistakes

• Thinking water blocks noise: Actually, sound travels farther and faster in water than in air.
• Believing dolphins and whales can just "shout louder": They try, but it uses more energy and can stress them out.
• Assuming only big noises matter: Even constant, lower-level noise (like ship engines) can cause problems over time.
• Forgetting about indirect effects: Noise can make animals leave good feeding or breeding areas, affecting their survival.

Remember it

Underwater noise is like living next to a never-ending traffic jam for dolphins and whales — it makes life hard and dangerous.