Noise is

Options

A. Loud sound
B. Unwanted sound
C. Constant sound
D. Sound of high frequency.

Answer

### Step-by-Step Text Solution

1. **Understanding the Concept of Noise**:
- Noise is generally understood as a type of sound. However, not all sounds are classified as noise.

2. **Defining Noise**:
- Noise can be defined as an "unwanted sound." This means that it is a sound that is not desired or appreciated by the listener.

3. **Characteristics of Noise**:
- Noise is often characterized as being unpleasant and disruptive to hearing. It can be loud and irritating, which makes it undesirable.

4. **Distinction Between Sound and Noise**:
- From a physical perspective, there is no significant difference between sound and noise; both are vibrations that travel through air or water.
- However, the distinction lies in the perception of the sound. What may be considered noise to one person may not be noise to another, depending on their preferences.

5. **Examples of Sound vs. Noise**:
- Loud sounds are not necessarily noise. For instance, loud music that one enjoys is not classified as noise, even though it is loud.
- Similarly, a constant sound, like someone singing or speaking pleasantly, is not considered noise.

6. **Conclusion**:
- The correct definition of noise is "unwanted sound." Therefore, the best option among the given choices is "unwanted sound."