The scope of this page is resonance disorders in children and adults. Resonance disorders—specifically hypernasality—are also discussed in ASHA's Practice Portal page on
Cleft Lip and Palate as they relate to clefting.
Velopharyngeal dysfunction (VPD) is discussed in this page as it relates to resonance disorders. See
Classification of Velopharyngeal Dysfunction [PDF]. For a discussion of articulation disorders that may co-occur with VPD and resonance disorders, see ASHA's Practice Portal page on
Cleft Lip and Palate.
Resonance disorders are not voice disorders, although they are often mislabeled as such. Resonance disorders should not be confused with conditions targeted by resonant voice therapy, an approach that emphasizes phonation with the least effort and impact on the vocal folds. See ASHA's Practice Portal page on
Velopharyngeal Dysfunction Evidence Map for summaries of available research on this topic as it relates to resonance disorders.
Speech resonance is the result of the transfer of sound produced by the vocal folds through the vocal tract comprised of the pharynx, oral cavity, and nasal cavity (Kummer, 2020a; Peterson-Falzone, Trost-Cardamone, Karnell, & Hardin-Jones, 2017). The vocal tract filters this sound, selectively enhancing harmonics based on the size and/or shape of the vocal tract. Perceived resonance is the result of this filtered tone.
The velopharyngeal (VP) valve plays an integral role in determining speech resonance; however, other aspects of the vocal tract also contribute to the perceived sound. These include the size and shape of the resonating cavities (pharynx, oral cavity, and nasal cavity), the position of the tongue, and the degree of mouth opening. Opening and closing of valves along the vocal tract (e.g., vocal cords, VP valve, and place of articulation) contribute to the size and shape of the vocal tract.
Normal resonance is achieved through an appropriate balance of oral and nasal sound energy, based on the intended speech sound. Resonance varies for vowels, oral consonants, and nasal consonants and also varies across languages and dialects. Most vowels and vocalic consonants in the English language are predominantly oral. Normal resonance has a range of acceptability and is perceived along a continuum (Peterson-Falzone, Hardin-Jones, & Karnell, 2010).
Resonance disorders result from too much or too little nasal and/or oral sound energy in the speech signal. They can result from structural or functional (e.g., neurogenic) causes and occasionally are due to mislearning (e.g., articulation errors that can lead to the perception of a resonance disorder).
Resonance is a function of sound—not airflow. Resonance disorders should not be confused with nasal airflow “errors” or distortions. Nasal airflow “errors” are related to articulation when there is an inappropriate escape of air through the nasal cavity during production of pressure consonants. Nasal airflow “errors” may be learned (e.g., nasal fricatives, pharyngeal fricatives, and phoneme-specific nasal emission), or they may be obligatory due to a palatal fistula or VPD. See ASHA's Practice Portal Page on
Cleft Lip and Palate for further discussion.
Resonance disorders include the following:
- Hypernasality—occurs when there is sound energy in the nasal cavity during production of voiced, oral sounds.
- Hyponasality—occurs when there is not enough nasal resonance on nasal sounds due to a blockage in the nasopharynx or nasal cavity.
- Cul-de-sac resonance—occurs when sound resonates in a cavity (oral, nasal, or pharyngeal) but is “trapped” and cannot exit because of an obstruction.
- Mixed resonance—presence of hypernasality, hyponasality, and/or cul-de-sac resonance in the same speech signal.