Name the waves used for echo depth sounding.

Explanation

**Step-by-Step Solution:**

1. **Understanding Echo Depth Sounding**: Echo depth sounding is a technique used to measure the depth of water bodies. It involves sending waves into the water and measuring the time it takes for the waves to return after hitting the bottom.

2. **Identifying the Type of Waves**: The waves used in echo depth sounding are typically sound waves, not light waves. Sound waves can travel through water and are effective for measuring distances underwater.

3. **Specific Type of Sound Waves**: In echo depth sounding, ultrasonic waves (high-frequency sound waves) are commonly used. These waves can penetrate water and provide accurate depth measurements.

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