Which is not the condition for hearing sound?

Options

A. There must be a vibrating body capable of transferring energy.
B. There must be a material medium to pick up and propagate energy.
C. The medium must have a large density.
D. There must be receiver to receive the energy and interpret it.

Explanation

To determine which option is not a condition for hearing sound, we can analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Identify the Conditions for Hearing Sound**:
- To hear sound, certain conditions must be met. These include:
- A vibrating body that produces sound.
- A medium (like air, water, or solids) to transmit the sound waves.
- A receiver (like the human ear) to detect the sound.

2. **Evaluate Each Option**:
- **Option 1**: There must be a vibrating body capable of transferring energy.
- This is a necessary condition because sound is produced by vibrating objects (like tuning forks or vocal cords).

- **Option 2**: There must be a material medium to pick up and propagate energy.
- This is also a necessary condition since sound cannot travel through a vacuum; it requires a medium to propagate.

- **Option 3**: The medium must have a large density.
- This is not a necessary condition for hearing sound. While the density of the medium affects the speed of sound, it does not prevent sound from being heard. Sound can still be heard in mediums with varying densities.

- **Option 4**: There must be a receiver to receive and interpret energy.
- This is essential because without a receiver (like the human ear), sound cannot be perceived, even if sound waves are present.

3. **Conclusion**:
- Based on the analysis, **Option 3** ("The medium must have a large density") is not a necessary condition for hearing sound. Therefore, it is the correct answer to the question.

### Final Answer:
**Option 3**: The medium must have a large density.

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