**Core Concept:** Assessing hearing in infants is crucial for early intervention and prognosis. The examination focuses on identifying infants with potential hearing loss, which can be caused by genetic, infectious, or acquired factors.

**Why the Correct Answer is Right:** The best time for hearing assessment in an infant is during the first year of life, specifically between 3-6 months. This is because the brain's auditory system develops rapidly during this period, making it an ideal time to evaluate the infant's hearing. Furthermore, this age range allows for early intervention if needed, which has a significant impact on language development and cognitive growth.

**Why Each Wrong Option is Incorrect:**

A. **3-6 years:** This age range is too late as the auditory system development is complete by then, making it challenging to identify potential hearing issues.

B. **After 12 months:** This option disregards the crucial window of auditory system development during the first year of life.

C. **After the second year:** Similar to option B, this option fails to consider the optimal time for assessing hearing during the first year of life.

D. **When the child starts speaking:** Speech development is not solely dependent on hearing ability and assessing hearing during this stage could lead to misinterpretation of the child's communication progress.

**Clinical Pearl:** Early identification and intervention for hearing loss in infants can lead to improved language development, social interaction, and overall cognitive functioning. Hence, it is essential to perform hearing assessments during the first year of life to maximize the chances of early intervention and positive outcomes.