When both source and observer approach each other with a speed a equal to the half the speed of sound, then determine the percentage change in frequency of sound as detected by the listener.

Explanation

To solve the problem of determining the percentage change in frequency of sound as detected by the listener when both the source and observer are approaching each other with a speed equal to half the speed of sound, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Doppler Effect Formula**:
The apparent frequency \( f' \) when both the source and observer are moving towards each other is given by the formula:
\[
f' = \frac{v + v_o}{v - v_s} \cdot f
...