Assessing Consonant Sound Production in Infants

During a routine health visit for a 6-month-old infant, the nurse assesses various developmental milestones. It is crucial to understand that at this age, infants typically exhibit significant physical and cognitive development. One key indicator of normal development involves the infant's ability to：

demonstrate social interaction by smiling at others and establishing eye contact. Furthermore, there is a specific number of words or sounds that babies normally start to produce.

Fill in the blank: By 6 months of age, an infant can typically respond to their name and may vocalize a combination of sounds that includes at least _____ consonant sounds.