Complete the following sentences :
If the amplitude of a sound is halfed, its loudness becomes

Explanation

To complete the sentence: "If the amplitude of a sound is halved, its loudness becomes..."

### Step-by-Step Solution:

1. **Understanding the Relationship**:
- We know that loudness (L) is directly proportional to the square of the amplitude (A). This can be expressed mathematically as:
\[
L \propto A^2
...