What type of sounds are most affected by hypernasality during speech production?

Hypernasality primarily affects non-nasal sounds during speech production. In individuals with hypernasality, the velopharyngeal port—the opening between the nasal cavity and the oral cavity—does not close properly during speech. As a result, air escapes through the nose when they attempt to produce oral sounds, which can lead to a distortion of those sounds.

Non-nasal sounds, such as plosives and fricatives, typically require a complete closure of the velopharyngeal port to direct airflow through the mouth for proper articulation. When this closure is inadequate due to hypernasality, these sounds can sound muffled or produced with excessive nasal resonance, leading to reduced clarity and intelligibility.

In contrast, nasal sounds—like /m/, /n/, and /ŋ/—are naturally produced with resonance in the nasal cavity, so they are less affected by the inability to close the velopharyngeal port. Therefore, non-nasal sounds are the most impacted by hypernasality, making them significantly distorted in individuals with this speech characteristic.