State the necessary conditions for the interference of two sound waves.

Explanation

To state the necessary conditions for the interference of two sound waves, we can outline the following steps:

### Step-by-Step Solution:

1. **Constant Phase Difference**:
- The first necessary condition for the interference of two sound waves is that the phase difference between the two waves must remain constant. This means that the waves should maintain a fixed relationship in their cycles, which allows for constructive or destructive interference to occur consistently.

2. **Nearly Equal Amplitudes**:
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