Nasal speech describes an abnormal resonance in a person’s voice, primarily caused by excessive airflow through the nose during speaking. This can make a voice sound muffled or as if the speaker is “talking through their nose.” Nasal speech can significantly impact a person’s ability to communicate clearly in daily interactions.
Understanding Nasal Speech
Nasal speech manifests as hypernasality or hyponasality. Hypernasality occurs when too much sound resonates in the nasal cavity, making speech sound excessively nasal, particularly on non-nasal sounds like vowels or pressure consonants (e.g., /p/, /t/, /k/). Conversely, hyponasality, also known as denasality, happens when there is insufficient airflow through the nose, making nasal sounds like /m/, /n/, and /ng/ sound similar to their oral counterparts (e.g., /b/, /d/, /g/).
Normal speech production relies on the velopharyngeal valve, which includes the soft palate (velum) and pharyngeal walls. For most speech sounds, this valve closes to direct airflow into the mouth, preventing air from escaping through the nose. When producing nasal sounds, this valve opens to allow air and sound to resonate in the nasal cavity.
In nasal speech, the coordination of the velopharyngeal mechanism is disrupted. In hypernasality, the velopharyngeal valve does not close completely, allowing air and sound to escape into the nasal cavity during oral speech sounds. This incomplete closure can lead to a reduction in oral air pressure, causing consonants that require high pressure (like /p/ or /s/) to sound weak or omitted.
Causes of Nasal Speech
Nasal speech stems from structural or neurological issues affecting the velopharyngeal mechanism. A common structural problem is velopharyngeal insufficiency (VPI), where the soft palate is too short or has an anatomical defect, preventing full closure against the back of the throat. This is often seen in individuals with a history of cleft lip and palate, even after surgical repair.
Neurological conditions can also lead to nasal speech, known as velopharyngeal incompetence. This happens when velopharyngeal structures are normal but do not move effectively due to impaired muscle control. Disorders like dysarthria, which affects speech muscle coordination, or conditions from traumatic brain injury, stroke, or cerebral palsy, can cause this dysfunction.
Enlarged adenoids or tonsils can sometimes contribute to nasal speech by physically obstructing the nasal airway, leading to hyponasal speech. Hearing impairment can also play a role, as individuals with reduced hearing may not adequately monitor their own speech production, potentially leading to abnormal resonance patterns.
Diagnosing Nasal Speech
Identifying nasal speech and its cause involves evaluation by a speech-language pathologist (SLP). Evaluation often begins with a perceptual assessment, where the SLP listens to the individual’s speech to assess nasal resonance, articulation errors, or nasal air emission. This subjective assessment helps differentiate between hypernasality and hyponasality.
Following perceptual evaluation, instrumental assessments provide objective data about velopharyngeal function. Nasometry is a computer-based tool that measures the acoustic characteristics of nasal airflow during speech. Videofluoroscopy is a specialized X-ray procedure that captures moving images of the soft palate and pharyngeal walls during speech, allowing visualization of velopharyngeal closure.
Another instrumental technique is nasoendoscopy (or nasopharyngoscopy), where a thin, flexible tube with a camera is inserted into the nostril to view the nasal cavity and velopharyngeal sphincter movement during speech. These objective measures help pinpoint the nature of the velopharyngeal dysfunction, whether structural, movement-related, or speech learning patterns, guiding the treatment plan.
Treatment for Nasal Speech
Treatment for nasal speech is tailored to the specific cause and often involves a combination of approaches. Speech therapy, guided by a speech-language pathologist, is important in improving speech clarity and resonance. Therapy techniques may focus on increasing awareness of oral versus nasal airflow, improving articulation by building oral air pressure for specific sounds, and adjusting tongue and jaw positioning to optimize resonance. While speech therapy can improve compensatory speech patterns, it generally cannot correct structural issues that prevent velopharyngeal closure.
For structural problems like velopharyngeal insufficiency, surgical interventions are often considered. Common surgical procedures aim to create a better seal between the oral and nasal cavities. Pharyngeal flap surgery involves creating a tissue flap from the back of the throat and attaching it to the soft palate, forming a bridge that reduces the nasal cavity opening. Sphincter pharyngoplasty is another surgical option where tissue from the sides of the throat is brought together to create a smaller, more effective velopharyngeal opening.
These surgical procedures are designed to reduce air escaping through the nose during speech. Following surgery, speech therapy is often continued to help the individual adapt to the altered anatomy and refine their speech production. A multidisciplinary team, including otolaryngologists, plastic surgeons, and audiologists, often collaborates to provide comprehensive care, especially for complex cases.