We can distinguish a shrill sound from a flat sound by its :

Options

A. amplitude
B. loudness
C. pitch
D. none of the above

Answer

To solve the question, "We can distinguish a shrill sound from a flat sound by its:", we need to analyze the options provided and understand the characteristics of the sounds mentioned.

### Step-by-Step Solution:

1. **Understand the Terms**:
- **Shrill Sound**: This type of sound is characterized by a high frequency and high pitch. It often sounds thin or sharp.
- **Flat Sound**: This sound is characterized by a lower frequency and lower pitch. It tends to sound deeper and fuller.

2. **Identify the Key Characteristic**:
- The primary difference between shrill and flat sounds lies in their pitch. Pitch refers to how high or low a sound is perceived.

3. **Evaluate the Options**:
- **Amplitude**: This refers to the height of the sound wave and is related to the loudness of the sound, not the pitch.
- **Loudness**: This is the perception of the intensity of the sound but does not distinguish between shrill and flat sounds.
- **Pitch**: This is the correct option as it directly relates to the frequency of the sound waves, allowing us to differentiate between high-pitched (shrill) and low-pitched (flat) sounds.
- **None of the Above**: This option is incorrect since we have identified pitch as the distinguishing factor.

4. **Conclusion**:
- Therefore, we can conclude that we can distinguish a shrill sound from a flat sound by its **pitch**.

### Final Answer:
We can distinguish a shrill sound from a flat sound by its **pitch**.