The loudness of sound is determined by the

Options

A. amplitude of vibration
B. ratio of amplitude and frequency of vibration
C. frequency of vibration
D. product of amplitude and frequency of vibration

Answer

### Step-by-Step Solution:

1. **Understanding Loudness**: Loudness is a subjective measure of sound intensity that we perceive. It is influenced by various factors, but primarily by the amplitude of the sound wave.

2. **Identifying the Options**: The question provides four options regarding what determines the loudness of sound:
- Option 1: Amplitude of vibration
- Option 2: Ratio of amplitude and frequency of vibration
- Option 3: Frequency of vibration
- Option 4: Product of vibration and frequency of vibration

3. **Analyzing Each Option**:
- **Option 1**: Amplitude of vibration - This is the height of the wave from its mean position. A greater amplitude means a louder sound.
- **Option 2**: Ratio of amplitude and frequency of vibration - This does not directly relate to loudness.
- **Option 3**: Frequency of vibration - While frequency affects the pitch of the sound, it does not determine loudness.
- **Option 4**: Product of vibration and frequency of vibration - This is not a standard measure for loudness.

4. **Conclusion**: The correct answer is **Option 1: Amplitude of vibration**. The greater the amplitude, the louder the sound.