The ability to hear often decreases with age because

Options

A. The cilia degenerate
B. The hair cell stiffen
C. The flexibility of the basilar membrane changes
D. The tympanic canal straightens

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks why the ability to hear often decreases with age. This involves understanding the physiological changes that occur in the auditory system as one ages.

2. **Identifying the Key Structure**: The organ responsible for hearing is the Organ of Corti, which is located in the inner ear. It plays a crucial role in converting sound vibrations into neural signals.

3. **Role of the Basilar Membrane**: The Organ of Corti is situated on the Basilar membrane, which is essential for hearing. The Basilar membrane is flexible and vibrates in response to sound waves at different frequencies.

4. **Age-Related Changes**: As a person ages, the flexibility of the Basilar membrane decreases. This reduced flexibility affects its ability to vibrate properly in response to sound frequencies, leading to a decline in hearing ability.

5. **Conclusion**: Therefore, the ability to hear decreases with age primarily because the flexibility of the Basilar membrane diminishes.

### Final Answer:
The ability to hear often decreases with age because the flexibility of the Basilar membrane decreases.

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