May 23, 2024

Nasometry Devices: Measuring Acoustical Properties of the Nasal Cavity

Nasometry devices analyze speech sounds produced in the mouth and nose to provide objective data on nasalance, or the degree to which speech is produced through the nose. By reflecting light or sound waves off the walls of the nasal cavity, these instruments are able to precisely measure physical properties of the nasal airway. The data collected can be used by speech language pathologists (SLPs) to diagnose and treat disorders affecting nasal resonance.

How Nasometry Works

All Nasometry Devices work on the principle of reflective measurement. During testing, the patient wears a small microphone near the nose and mouth while repeating calibrated speech samples. These may include sentences, phrases, or individual sounds containing both oral and nasal consonants. As the patient speaks, acoustic signals from the oral and nasal cavities are separated. Light-based systems shine an infrared beam into the nose, while acoustic systems use ultrasonic sound waves. In both cases, the reflection is picked up by sensors and analyzed by the device’s computer software. This analysis produces objective measurements of variables like nasalance score, oral-to-nasal flux ratios, and acoustic patterns over time. Graphical reports compare a patient’s performance to normative data.

Clinical Applications of Nasometry

Some of the main clinical uses of nasometry include:

– Diagnosing and monitoring velopharyngeal inadequacy (VPI). VPI occurs when the soft palate does not properly seal the nasal from the oral cavity during speech. Nasometry can quantify the degree of nasal air emission objectively.

– Evaluating the results of pharyngeal flap surgery. This procedure is sometimes used to treat VPI by partially covering the nasopharynx. Pre- and post-operative nasometry tests objectively demonstrate surgery outcomes.

– Differentiating rhinolalia aperta from rhinolalia clausa. These terms refer to hypernasal and hyponasal speech. Nasometry quantifies the oral-nasal balance to distinguish between the two.

– Planning and monitoring treatment for cleft palate and other craniofacial anomalies. Nasalance scores show how speech production changes with palate repair, pharyngeal flap surgery, or orthodontic adjustments.

– Diagnosing and managing nasal airway disorders. Conditions affecting nasal patency like deviated septum or nasal polyps can be identified. Nasometry also tracks pre- versus post-treatment resonance.

Commonly Used Nasometry Systems

There are a few principal brands of nasometry equipment used in clinical practice. Each has its own technical approach and strengths.

– Nasometer II (KayPentax) – The original and most widely used system. It uses paired microphones and infrared reflectance to measure nasalance. User-friendly interface for clinicians.

– NasalView (Rhinometrics) – State-of-the-art light-based system. Extra sensors allow for more detailed analysis of nasal airflow patterns over time. Slightly more complex to operate.

– MicroAid Nasometer – More portable acoustic system using ultrasonic pulses. Convenient for use outside the clinic or with young children. Provides basic nasalance scores.

– Visi-Pitch – A combined system for nasometry and acoustic analysis of pitch, loudness, and other voice qualities. Comprehensive tool useful for craniofacial patients.

Each device has been clinically validated and can provide objective, quantifiable data to guide differential diagnosis and treatment planning for nasal-oral balance disorders. Experienced SLPs consider the individual patient’s needs to select the best nasometry system in each case.

Reliability and Clinical Utility of Nasometry

Considerable research has established nasometry as a reliable and valid method for assessing nasalance. Studies have shown:

– Minimal variability in repeated measures on the same patient when administered by trained SLPs. This confirms the instruments’ good test-retest reliability.

– Nasometry scores correlate well with auditory-perceptual judgments of resonance by experienced listeners. So the objective data relates meaningfully to clinical impression.

– Detecting real pre- versus post-treatment differences in most patients. Nasometry can statistically quantify small but clinically significant changes in nasal-oral balance.

– Normative databases allow nasalance results to be interpreted against expectations for a patient’s sex, age, and dialect. This contextualizes individual performance.

In summary, over 40 years of clinical use and research support nasometry as the gold standard objective technique for diagnosing and monitoring disorders of nasal resonance. When combined with detailed case history and auditory-perceptual evaluation, nasometry provides invaluable data to guide interdisciplinary craniofacial team management. It remains a cornerstone technology for SLPs specializing in resonance disorders.

1.Source: Coherent Market Insights, Public sources, Desk research
2.We have leveraged AI tools to mine information and compile it