Final answer:
The most appropriate diagnostic evaluation for a 2 month-old infant with no apparent response to a sudden loud sound is hearing tests such as automated auditory brainstem response (ABR) or otoacoustic emissions (OAE) tests which are specifically designed for evaluating hearing in infants.
Step-by-step explanation:
The most appropriate diagnostic evaluation for a 2 month-old infant who presents with no apparent response to a sudden loud sound would be hearing tests specifically tailored for infants, such as the automated auditory brainstem response (ABR) test or the otoacoustic emissions (OAE) test. These tests are noninvasive, quick, and can be performed while the infant is sleeping or lying still. The tests measure the infant's hearing sensitivity and can detect hearing loss.
It's essential to diagnose potential hearing issues early on, as hearing is crucial for the development of speech and language skills. Sounds that the infant heard before birth, such as a parent's breathing and heartbeat, are comforting, and young infants show a clear preference for voices, especially their mother's voice. Detecting hearing problems early can ensure that appropriate interventions can be provided to support the infant's development.
It should be noted that it is common for newborns to startle at sudden or loud noises, and if this reaction is absent, it could be an indicator of a hearing problem, underscoring the importance of the recommended hearing tests.