Question

1. The number of vibrations produced per second

which we cannot hear
2. The sound which doesn’t have a pleasant sensation on the ears.

3. The unit of frequency

4. Low frequency sound
Answer in one word
✌️✌️✌️✌️✌️✌️
​

Answer 1

Answer:

1. below 20hz and above 20,000hz

2. noise

3. Hertz

4. Infrasound like thunder