Speech production involves vibration of sounds through the oral and nasal cavities. Resonance is the term used to describe the amount and location of these vibrations. The pathways of produced sounds and associated vibrations are important as they help shape speech sounds and determine the quality of voice. A child speaking with normal resonance effectively closes off the oral cavity and the nasal cavity during the production of sounds. This prevents air from escaping through the nose and allows the child to build up air pressure in the mouth for sound production. However, there are circumstances in which air escapes through the nose or the air is blocked during speech. This produces a vocal quality that may sound nasal and sometimes be difficult to understand.

Hyponasality occurs when airflow and sound vibrations are being blocked from entering the nasal cavity. During speech production, the child may sound “stopped up” such as with a cold or sinus infection. However, the most common physical blockage is enlarged tonsils or adenoids that block or alter the vibrations. This vocal quality is most noticeable when producing vowels and nasal consonants such as /m/, /n/, and /ng/.

Hypernasality occurs when air moves from the oral cavity into the nasal cavity during speech production. This is often present with children who have a history of cleft palate or submucous cleft palate. The voice quality sounds as if the child is talking through the nose. This is most commonly observed when producing the vowel sounds /u/ and /i/ as well as voiced consonants /b/, /d/, /g/. In some instances, a child may exhibit nasal air emission in which air escapes out of the nose and can actually be heard during production of certain consonants (e.g. /p/, /t/, /k/, /s/, /sh/, and /ch/).

Causes may include:

If structural issues are causing the hyponasal or hypernasal voice quality, there are surgical options available to correct these issues. These may include: