SNORS

Super Nasal-Oral Ratiometry System

SNORS is a portable, USB-powered nasal-oral airflow system that provides an objective measure of velopharyngeal closure by measuring aerodynamic nasalance, defined as the percentage of the total airflow that is nasal during speech. It uses a lightweight dual-chamber mask, fitted with rapid-response airflow sensors and microphones for independent nasal and oral measurement. SNORS is used by speech and language professionals and researchers in specialist hospitals, university programmes, and cleft palate services worldwide.

Get Quote Request a demo

How SNORS measures velopharyngeal closure

Unlike traditional anemometry, which measures only nasal airflow, SNORS measures both nasal and oral airflow simultaneously. By calculating the ratio of nasal to total airflow, SNORS reduces sensitivity to variations in speech loudness and produces more consistent measurements across different speakers and tasks. SNORS also uses rapid-response airflow sensors capable of tracking the fast movements of the velum during speech.

Aerodynamic vs acoustic nasalance

Aerodynamic nasalance provides a measure of effective velopharyngeal closure, whereas acoustic nasalance (defined as the percentage of the total acoustic energy that is nasal, and often referred to simply as nasalance) relates to the perceived nasality of speech. Both measures are useful and complementary.

Aerodynamic nasalance equation — nasal airflow divided by total airflow × 100. Acoustic nasalance equation — nasal acoustic energy divided by total acoustic energy × 100.

Aerodynamic nasalance has practical advantages over acoustic nasalance measurement. Unlike acoustic nasalance, it is not affected by resonant frequencies, acoustic crossover or background noise, and can be calculated for both voiced and unvoiced sounds. Crucially, aerodynamic nasalance is near zero when velopharyngeal closure is maintained, regardless of nasal cavity resonance or vowel context. Interpretation is therefore more straightforward than acoustic nasalance.

Phoneme Aerodynamic nasalance (%) Acoustic nasalance (%)
/i/ (High vowel) 1.68 12.56
/ɑ/ (Low vowel) 2.01 5.23
/m/ 99.87 97.04
/n/ 99.86 96.14
/ŋ/ 98.92 97.15
/s/ 2.26 N/A
/p/ 3.28 N/A

Aerodynamic nasalance measured with SNORS; acoustic nasalance measured with the Nasality Microphone. Values from a single normal English-speaking adult.

SNORS mask

SNORS Mask
  • Lightweight dual-chamber mask separates nasal and oral signals
  • Soft silicone cuff moulds to the contours of the face for a comfortable airtight seal
  • Rapid-response airflow sensors detect the fast movements of the velum during speech
  • Nasal and oral microphones record nasal and oral speech signals for acoustic analysis
  • Adult and child (4+) sizes available
  • Child mask available in a range of colours

SNORS processor unit

SNORS processor unit
  • Quick-release connector for interchangeable adult and child masks
  • Volume control for optimised audio recording levels
  • Auxiliary channel for simultaneous recording from external devices
  • USB powered — no external power supply required
  • Connects to any Windows desktop, laptop, or tablet

Who uses SNORS

SNORS is used by speech and language professionals and researchers in specialist hospitals, university programmes, and cleft palate services worldwide to obtain an objective measure of velopharyngeal closure across a wide range of speakers and populations.

Velopharyngeal insufficiency (VPI)
Used to obtain objective nasal-oral airflow measurements and aerodynamic nasalance data in speakers with velopharyngeal insufficiency.
Cleft palate research & practice
Used by researchers and speech professionals working with cleft palate populations to measure velopharyngeal closure and nasal-oral airflow in speakers with hypernasality and nasal emission. Enables objective comparison of airflow data before and after palate repair or other intervention.
Motor speech populations
Used to measure nasal and oral airflow in speakers with motor speech disorders, including dysarthria and neurological conditions affecting velopharyngeal function.
Maxillofacial surgery
Used to obtain objective airflow measurements in speakers following maxillofacial or orthognathic surgery, enabling before-and-after comparison of velopharyngeal closure data.
Visual biofeedback
Real-time airflow displays and the animated 3D velopharyngeal model provide visual biofeedback during speech, making velopharyngeal closure immediately visible to the speaker. Suitable for both clinical and research settings.
Research
Used in academic and clinical research investigating velopharyngeal function and nasal-oral airflow. Applications include normative data collection, multilingual studies, and instrumental measurement of velopharyngeal closure across different speaker populations.

Why speech professionals choose SNORS

  • ✓  Unambiguous velopharyngeal closure measurement — aerodynamic nasalance approaches zero when velopharyngeal closure is maintained, regardless of nasal cavity resonance or vowel context, making it more straightforward to interpret than acoustic nasalance.
  • ✓  No acoustic interference — unlike acoustic nasalance measurement, aerodynamic nasalance is not affected by resonant frequencies, acoustic crossover, or background noise.
  • ✓  Measures voiced and unvoiced sounds — aerodynamic nasalance can be calculated for both voiced and unvoiced sounds, unlike acoustic nasalance which is limited to voiced sounds only.
  • ✓  Simultaneous aerodynamic and acoustic recording — captures nasal and oral airflow alongside speech signals in a single lightweight, USB-powered system.
  • ✓  Adult and child sizes — interchangeable adult and child masks with a quick-release connector, suitable for speakers aged 4 and above.
  • ✓  Compatible software — works with SNORS 3D and icSpeech Professional Edition, with real-time nasal-oral airflow displays, 3D velopharyngeal visualisation, biofeedback games, and offline analysis.
  • ✓  Published research — described in peer-reviewed literature and used in published studies investigating velopharyngeal function, nasal-oral airflow, and hypernasality.
  • ✓  Trusted worldwide — used by universities, hospitals, and research institutions worldwide, built on over 30 years of speech technology development.
Aarhus University University of Florida Laboratoire de Phonétique et de Phonologie University of Cyprus Osaka Health Science University Moor House School and College Penn Medicine Fundacja Rozszczepowe Marzenia Smile House Fondazione
  • Aarhus University
  • University of Florida
  • Laboratoire de Phonétique et de Phonologie
  • University of Cyprus
  • Osaka Health Science University
  • Moor House School and College
  • Penn Medicine
  • Fundacja Rozszczepowe Marzenia
  • Smile House Fondazione

Software options

SNORS 3D

SNORS 3D uses an animated 3D model of the vocal tract to illustrate velopharyngeal closure and the resultant nasal and oral airflows. Nasal airflow, oral airflow, and aerodynamic nasalance are also displayed numerically.

SNORS 3D lateral view showing 100% aerodynamic nasalance and nasal airflow during playback — velopharyngeal closure measurement SNORS 3D statistics panel showing mean and maximum nasal airflow, oral airflow, and aerodynamic nasalance values from a recorded speech sample SNORS 3D animated vocal tract model showing nasal inhalation — cross-section view with green airflow streams SNORS 3D animated vocal tract model showing oral airflow during speech

The animated 3D model consists of the lips, teeth, tongue, lower jaw, hard palate, soft palate and uvula. The transparency of these articulators can be adjusted to reveal hidden structures, and the model can be rotated 360°. Airflow illustrates the difference between nasal, oral, voiced and voiceless sounds.

SNORS 3D • nasal airflow (soft palate lowered)

Nasal airflow (soft palate lowered)

SNORS 3D • oral airflow (soft palate raised)

Oral airflow (soft palate raised)

SNORS 3D • voiced airflow (intermittent flow)

Voiced airflow (intermittent flow)

SNORS 3D • voiceless airflow (continuous flow)

Voiceless airflow (continuous flow)

SNORS 3D • exhalation (blue flow)

Exhalation (blue flow)

SNORS 3D • inhalation (green flow)

Inhalation (green flow)

  • Real-time visual feedback of velopharyngeal closure
  • Off-line analysis of aerodynamic nasalance
  • Auditory playback of recorded speech
  • Photorealistic and stylised views
  • 360° model rotation
  • Adjustable articulator transparency
  • Windows 10 64-bit and 11 64-bit compatible

icSpeech Professional Edition

icSpeech Professional Edition is a comprehensive speech visualisation and analysis package that significantly extends the capability of SNORS, providing a wider range of aerodynamic and acoustic displays, data recording, and biofeedback games. It also supports multiparameter recording, allowing airflow data to be combined with electropalatography (EPG), electroglottography (EGG), nasometry, and video.

icSpeech Professional Edition displaying nasal airflow, oral airflow and speech waveforms with spectrogram during SNORS measurement icSpeech Professional Edition • exported speech, nasal and oral airflow waveforms SNORS nasal-oral airflow analysis of the word 'Missing' — showing nasal airflow intensity, oral airflow intensity, and aerodynamic nasalance over time icSpeech Professional Edition Skywriter biofeedback game showing aerodynamic nasalance in real time during speech therapy icSpeech Professional Edition dynamic bar chart display showing aerodynamic nasalance, nasal airflow and oral airflow during SNORS measurement
  • Aerodynamic and acoustic displays including waveforms, dynamic bar charts and spectrograms
  • Data recorder with picture and text prompting — import or create custom prompts
  • Six biofeedback games with adjustable targets and rewards
  • Compare multiple recordings simultaneously
  • Export raw data to CSV for external processing
  • Attach user notes to recordings
  • Windows 10 and 11 compatible

icSpeech Professional Edition provides the following SNORS parameters:

Parameter Description
Nasal airflow Unfiltered nasal airflow signal
Nasal airflow intensity Low pass filtered nasal airflow envelope
Oral airflow Unfiltered oral airflow signal
Oral airflow intensity Low pass filtered oral airflow envelope
Combined airflow Combined nasal and oral airflow
Combined airflow intensity Low pass filtered combined airflow envelope
Aerodynamic nasalance Percentage of the total airflow that is nasal
Aerodynamic ratio Ratio of the difference between nasal and oral airflow to the total airflow
Nasal speech Nasal acoustic signal
Nasal speech intensity Low pass filtered nasal speech envelope
Oral speech Oral acoustic signal
Oral speech intensity Low pass filtered oral speech envelope
Speech Combined nasal and oral acoustic signal
Speech intensity Low pass filtered speech envelope
Pitch Derived from the combined acoustic signal
Acoustic nasalance* Percentage of the total acoustic energy that is nasal
Auxiliary Signal derived from user defined auxiliary channel

* Acoustic nasalance measured by SNORS is less accurate than that measured by the Nasality Microphone, due to the limited acoustic separation achievable within the mask.

Video guides

This presentation introduces SNORS and provides an overview of its key features, mask design, and compatible software options.

System specification

Microphones

Parameter Value
Left channel Nasal speech
Right channel Oral speech
Type Electret condenser
Polar pattern Cardioid
Frequency response 100 – 15,000Hz
Sensitivity -60dB at 1kHz (0dB = 1V/Pa)
Output impedance 2.2k ohm
Supply voltage +2.5V

Airflow sensors

Parameter Value
Maximum range (full scale) +1000 sccm
Common mode pressure 25psi
Response time 3msec
Minimum operating temperature -25°C
Maximum operating temperature +85°C
Supply voltage +10V

Auxiliary channel

Parameter Value
Voltage range ±2.5V
Connectivity 50 ohm BNC Coaxial Jack
Acquisition sample rate 8000 samples per second

System requirements

Parameter Value
Supported operating systems Windows 10 and 11
Supported computers Desktop, laptop, tablet
Connectivity USB 1.0, 2.0, 3.0
Power USB bus powered

Package contents

SNORS is supplied as a complete hardware package. Choose from two software options to suit your requirements.

  • SNORS processor unit
  • SNORS mask (adult or child)
  • Locking USB cable
  • User manual
  • 12-month manufacturer's guarantee
  • SNORS 3D software (optional)
  • icSpeech Professional Edition software (optional)
Get Quote Request a demo
SNORS nasal-oral airflow measurement system — adult mask with rapid-response airflow sensors and processor unit

Frequently asked questions

Aerodynamic nasalance is the percentage of the total airflow that is nasal during speech. It is calculated from simultaneous nasal and oral airflow signals recorded by the SNORS mask, and provides an objective measure of velopharyngeal closure. Aerodynamic nasalance can be calculated for both voiced and unvoiced sounds.

The term follows the convention established by Fletcher (1970), who coined "nasalance" to describe the ratio of nasal to total acoustic energy during speech — aerodynamic nasalance applies the same ratio principle to airflow rather than acoustic energy.
Because aerodynamic nasalance is derived from airflow sensors, it is not affected by resonant frequencies — unlike acoustic nasalance, which is influenced by the resonant properties of the vocal tract. It is also not affected by acoustic crossover between the nasal and oral chambers, or by background noise — making SNORS robust in a wide range of clinical and research settings. Additionally, aerodynamic nasalance can be calculated for both voiced and unvoiced sounds, whereas acoustic nasalance is limited to voiced sounds only. Aerodynamic nasalance also approaches zero when velopharyngeal closure is maintained, regardless of nasal cavity resonance or vowel context.
Acoustic nasalance measures the ratio of nasal to total acoustic energy. Even with effective velopharyngeal closure, nasal cavity resonance can generate a measurable nasal acoustic signal. This occurs because intense oral airflow can cause the velum to flex under high intra-oral pressure, acoustically coupling energy into the nasal cavity — an effect particularly associated with vowels produced at high intra-oral pressure. Acoustic nasalance values also vary with vowel context due to differences in vocal tract resonance between vowel sounds. In these situations, a non-zero acoustic nasalance score does not necessarily indicate incomplete velopharyngeal closure. Aerodynamic nasalance is not subject to these effects — when no nasal airflow is present, aerodynamic nasalance approaches zero regardless of nasal cavity resonance or vowel context (Sharp, 2000).
SNORS and the Nasality Microphone measure different but complementary aspects of speech. The Nasality Microphone measures acoustic nasalance — the ratio of nasal to total acoustic energy — which relates to the perceived nasality of speech. SNORS measures aerodynamic nasalance — the ratio of nasal to total airflow — which provides a measure of effective velopharyngeal closure. Both measures are useful and complementary. Used together, they provide a more complete picture of velopharyngeal function than either instrument alone.

Although SNORS also records acoustic signals via microphones in both chambers of the mask, the acoustic nasalance is less accurate than that measured by the Nasality Microphone. This is due to the limited acoustic separation achievable within the mask.
Yes. SNORS measures nasal and oral airflow simultaneously, making it well suited for obtaining objective airflow data in speakers with nasal emission. The ratio of nasal to total airflow — aerodynamic nasalance — provides a quantitative measure of the degree of nasal emission during speech, enabling objective comparison of airflow data across different speech tasks and over time.
Yes. SNORS is used by speech and language professionals and researchers to obtain objective nasal-oral airflow measurements in speakers with velopharyngeal insufficiency (VPI). Aerodynamic nasalance provides a quantitative measure of velopharyngeal closure, and SNORS supports both real-time measurement and off-line analysis of recorded speech samples.
Pressure-flow systems such as the Aerophone measure both intraoral air pressure and nasal airflow, allowing calculation of velopharyngeal orifice area. SNORS measures nasal and oral airflow simultaneously without intraoral pressure measurement, calculating aerodynamic nasalance as the ratio of nasal to total airflow. SNORS does not calculate velopharyngeal orifice area. However its portable, USB-powered design and significantly lower cost make it accessible in settings where laboratory pressure-flow systems are not practical. SNORS and pressure-flow systems are complementary instruments addressing different aspects of aerodynamic measurement.
Yes. SNORS has been used in peer-reviewed research and published studies investigating velopharyngeal function, nasal-oral airflow, and hypernasality. The instrument is described in peer-reviewed literature, including Sharp, Kelly, Main and Manley (1999), Medical Engineering & Physics, 21(9), 661–671. When citing SNORS in publications, please reference it as:

SNORS, icSpeech, a division of Rose Medical Solutions Ltd., Canterbury, UK.

A list of publications featuring icSpeech technology is available on the icSpeech publications page.
Yes. Normative aerodynamic nasalance data for 40 normal-speaking English-speaking adult subjects using the standard SNORS word list is presented in Sharp, P. (2000), Development of a Multiparameter Speech Analysis System, PhD thesis, University of Kent. Mean aerodynamic nasalance for purely oral words (type, fight, seat, cheese, shoot) lies between 6.5% and 13.5%, while words with a nasal element (begin, smoke, king, missing, end) range from 21.8% to 52.4%. Please contact us for further guidance on interpreting aerodynamic nasalance values in specific populations and languages.
No. SNORS does not require calibration. However, on first use, the software will guide you through a simple airflow offset removal procedure.
Yes. SNORS masks are available in both adult and child sizes, suitable for children aged 4 and above. The child mask is available in a range of colours. The soft silicone cuff and lightweight mask design make it comfortable for use with younger speakers. SNORS 3D provides an engaging 3D animated display that is particularly effective when working with paediatric speakers.

While most children aged 4 and above can use the SNORS mask comfortably, some younger or anxious children may find the mask unfamiliar. In these cases, familiarising the child with the mask before measurement and using SNORS 3D's animated display as a motivational tool can help. The Nasality Microphone may be more appropriate for children who are unable to tolerate the mask.
The SNORS mask is easy to dismantle and clean. The reusable soft silicone cuff can be sterilised in an autoclave at temperatures up to 134°C (±3°C). The flexible nylon casing and sensor housing can be thoroughly cleaned with disposable disinfection wipes. Replacement silicone cuffs are available to order. Please contact us for specific hygiene guidance relevant to your setting.
SNORS 3D and icSpeech Professional Edition currently support Windows 10 and Windows 11 only. The SNORS hardware uses standard USB and is not platform-restricted, but the software requires Windows. Users working in Mac environments may wish to run Windows via Boot Camp or a virtual machine. Please contact us to discuss your setup.
SNORS is compatible with two software options. SNORS 3D provides real-time visual feedback of velopharyngeal closure and aerodynamic nasalance using an animated 3D model of the vocal tract, and is well suited to clinical and research settings. icSpeech Professional Edition is a comprehensive multiparameter speech visualisation and analysis package providing 17 aerodynamic and acoustic parameters, six biofeedback games, and extensive analysis and data export features. Both packages support Windows 10 and 11.
Yes. icSpeech supplies universities, hospitals, and research institutions globally. We provide formal quotations suitable for institutional procurement processes and grant applications. Please use the Get quote form and indicate your institution type. We will respond promptly with appropriate pricing and documentation.
The SNORS auxiliary channel accepts analogue signals with a voltage range of ±2.5V from external devices, allowing simultaneous recording alongside nasal and oral airflow data. Devices connected via the auxiliary channel have included electromyography (EMG) systems — see Dominguez and Kelly (2002), Speech Rehabilitation Assessment using the SNORS+ System incorporating EMG: Phonetic Analysis, 3er Congreso Internacional sobre Investigacion en Ingenieria Electrica y Electronica, Mexico. Please contact us to discuss your multiparameter recording requirements.
Yes. SNORS is available worldwide. icSpeech ships directly to customers in many countries, and SNORS is also available through a network of regional distributors. Please contact us to find your nearest distributor or to arrange direct purchase.

Intended use: SNORS is a general measurement instrument for use by speech and language professionals, researchers, and educators. It is not intended for use as a medical device for the diagnosis, prevention, monitoring, or treatment of disease.