Which frequency produces a sound that can be heard by a person?

Options

A. 100 kHz
B. 40 kHz
C. 2 kHz
D. 30 kHz

Answer

To determine which frequency produces a sound that can be heard by a person, we need to consider the range of human hearing. The typical range of human hearing is from approximately 20 Hz to 20 kHz (20,000 Hz).

### Step-by-Step Solution:

1. **Understanding Human Hearing Range**:
- The human ear can generally detect sounds in the frequency range of 20 Hz to 20 kHz. Frequencies below 20 Hz are considered infrasound, and those above 20 kHz are considered ultrasound.

2. **Analyzing the Given Options**:
- The question provides several frequency ranges and asks which of these can be heard by a person.
- Options include:
- 100 kHz
- 20 kHz
- 100 kHz to 20 kHz
- More than 20 kHz
- 40 kHz
- 2 kHz
- 20 Hz and then 20 kHz
- 30 kHz

3. **Identifying Frequencies within the Hearing Range**:
- From the options:
- **100 kHz**: Above the hearing range (not audible).
- **20 kHz**: Upper limit of the hearing range (audible).
- **100 kHz to 20 kHz**: Includes frequencies above the hearing range (not audible).
- **More than 20 kHz**: Not audible.
- **40 kHz**: Not audible.
- **2 kHz**: Within the hearing range (audible).
- **20 Hz and then 20 kHz**: Both are within the hearing range (audible).
- **30 kHz**: Not audible.

4. **Conclusion**:
- The frequencies that can be heard by a person from the given options are **2 kHz** and the range **20 Hz to 20 kHz**.

### Final Answer:
The frequencies that produce a sound that can be heard by a person are **2 kHz** and **20 Hz to 20 kHz**.