The questions addressed here range from very general, to very specific. If your question is not answered here, it may already be addressed at the product-in-question's page. If it isn't, please feel free to contact us (Our contact information is listed at the bottom of every page, and on the Contact Us page.) This list will be updated periodically.
Questions
General
- Can your software be run on a laptop computer?
- Will Glottal Enterprises software work on my Mac?
- How much do these systems cost?
- How long has Glottal Enterprises been involved in the measurement of nasalance?
Nasality Visualization System (NVS)
- What are the relationships between the NAS systems, the NEM systems and the NVS system?
- How does the NEM system for recording nasal emission work? Is it accurate enough for research applications?
- Some clinicians believe that the measure “nasalance” refers only to the numbers resulting from one of the versions of a nasometer marketed by KayPentax, or previously by Kay Elemetrics. Is that true?
- Is it true that when a new version of a nasalance measurement system is put on the market, it is necessary to duplicate previous evaluation studies?
- Are the placement and orientation of the microphones and partition important for proper nasalance values to be obtained?
- Should nasal consonants (periods during which there is an oral closure and no velopharyngeal closure) be included in measurements of average nasalance?
- Why does the Glottal Enterprises system for measuring nasalance have periods in the chart during which no nasalance is computed? There are no such gaps evident in the charts generated by some competitive nasalance measuring systems.
- How does the Glottal Enterprises system for automatically marking nasal consonants work? Is it reliable for patients having a speech disorder?
- Can the so-called SNAP test (Simplified Nasometric Assessment Procedure, as described by Ann W. Kummer in Cleft Palate and Craniofacial Anomalies, Singular Press, 2001) be used with the NAS-1 system?
- Can systems for measuring nasalance be used for measuring nasal emission in pressure consonants?
- Can a system for measuring nasal emission in pressure consonants also measure nasal airflow in vowels?
Airflow/Air Pressure/Inverse Filtering
- Can the OroNasal mask be used to obtain separate simultaneous measures of nasal and oral airflow? If so, would such a display be useful for evaluating velopharyngeal insufficiency?
- How do the Glottal Enterprises airflow and pressure calibrators work?
Electroglottograph
- Please describe the optional Fundamental Frequency Trigger Output of the EG2 electroglottograph.
- How can EGG signals be displayed, other than using the Waveview software?
- Why do some subjects show an EGG signal with more noise than others?
Answers
General
- Can your software be run on a laptop computer?
Answer:
All of our systems have no problems running on a laptop or a netbook computer, or even most older Windows computers. The hardware for each product has a built-in analog-to-digital converter and need only be plugged into one of your computer's USB ports.
- Will Glottal Enterprises software work on my Mac?
Answer:
Our software will run on the newer Macintosh computers that have an Intel microprocessor and can run Windows. If you have an older Mac, we believe that the Windows environment is not a significant limitation now that computers have come down so much in price. Our Nasality Visualization System can operate satisfactorily on even a small "netbook" laptop that costs less than $300.
- How much do these systems cost?
Answer:
Because of the many options and configurations available with our systems, our prices are not published on the web. Email or call us for a quote. If you describe your application in your request, we can usually be helpful in recommending system configurations that might best meet your needs.
- How long has Glottal Enterprises been involved in the measurement of nasalance?
Answer: Glottal Enterprises has been marketing state-of-the-art aerodynamic measurement systems worldwide for over 30 years and has marketed systems for measuring nasalance since 1992. In the research lab of Glottal Enterprises' founder Martin Rothenberg, nasalance was explored about 25 years ago in the development of speech communication aids for the hearing impaired (described in the article Optimizing Sensory Substitution, in the proceedings of Advances in Prosthetic Devices for the Deaf: A Technical Workshop, National Technical Institute for the Deaf, August, 1978). The experience in that research has also gone into our present products.
Nasality Visualization System (NVS)
- What are the relationships between the NAS system, the NEM system and the NVS system?
Answer:
There are a number of ways that our systems for visualizing nasality can be purchased. The full Nasality Visualization System (NVS) includes the capability for measuring Nasal Emission (NEM-1, formerly NE-1) and the system for measuring nasalance (NAS-1 system). As part of the NVS system, the NAS-1 system has both the mask and partition options. (Nasal Emission measurement requires the mask.) There is a price advantage when purchasing the complete NVS system over purchasing the NAS-1 and NEM-1 separately.
- How does the NEM system for recording nasal emission work? Is it accurate enough for research applications?
Answer:
The NEM-1 system uses the standard Glottal Enterprises dual-chamber (OroNasal) mask to isolate nasal airflow. The flow rate is measured by a transducer mounted in the mask handle, as is the acoustic signal. The software records and displays both signals simultaneously and they are superimposed on the screen in a chart display. (See the dual-chamber mask and a typical screen at http://www.glottal.com/Products/NVS.htm#NE1.) Average values of NE and SPL can be obtained for a chosen speech segment. You definitely can do research measuring nasal emission with the NEM-1. It is also useful in speech training tasks.
- Some clinicians believe that the measure “nasalance” refers only to the numbers resulting from a version of a nasometer marketed by KayPentax, or previously by Kay Elemetrics. Is that true?
Answer:
No, this is not true. The term ‘nasalance’ was proposed by Fletcher and his associates in the early 1970s for the variable measured by his various TONAR systems. KayPentax later adopted it for their version of the TONAR system. It was not originally proposed by KayPentax. [Fletcher, S.G. and Frost, S.D., Quantitative and Graphic Analysis of Prosthetic Treatment for Nasalance in Speech, J. of Prosthetic Dentistry, Vol. 32, 284-91 (1974); Fletcher, S.G., Nasalance vs. Listener Judgments of Nasality, Cleft Palate-Craniofacial Journal, Vol. 13, 31-44 (1976)] The term ‘nasalance’ was put forth as a generic term for this type of measurement and is used that way in the literature. For example, Tim Bressman, in the article "Comparison of Nasalance Scores Obtained With the Nasometer, the NasalView and the OroNasal System" (Cleft Palate-Craniofacial Journal, Vol. 42, No. 4 (2005)) recognizes that there are at least three systems being marketed that measure nasalance. This assumption was accepted by the reviewers and the Journal editors, and has never been challenged in the literature. The term ‘nasalance’ is not a trademark, but a descriptor for a general type of measurement. As another example, Baken and Orlikoff, in their widely respected book Clinical Measurement of Speech and Voice, state that "The term nasalance has been coined to describe this measure". Thus nasalance describes a measure, not the output of a specific device, just as the word ‘weight’ describes a measure, not the reading of a particular scale.
- Is it true that when a new version of a nasalance measurement system is put on the market, it is necessary to duplicate previous evaluation studies?
Answer:
It is not necessary for a newcomer to a field to replicate previous testing. It is only necessary to determine that the new system is essentially equivalent to, or better than, the old one in performance.
- Are the placement and orientation of the microphones and partition important for proper nasalance values to be obtained?
Answer:
Using a handle or headset with a partition resting on the upper lip, measurements of nasalance will vary somewhat with the angle at which the partition meets the face. This is true of all devices employing a partition held against the upper lip. However, when using the Glottal Enterprises OroNasal mask for nasal and oral sound separation, the orientation of the mask handle does not affect the readings, as long as the mask makes contact with the face. Thus, the convenience of the partition and the lack of speech muffling may make it preferable for speech training, classroom demonstration, studies of the singing voice and many clinical measurement applications. For the stability required for some research purposes, the mask may be preferred. The Glottal Enterprises nasalance measurement systems offer the user a choice.
- Should nasal consonants (periods during which there is an oral closure and no velopharyngeal closure) be included in measurements of average nasalance?
Answer:
Mixing of nasal consonants and vowels in a nasalance reading is theoretically incorrect. Nasalance is only properly defined during vowels and vowel-like consonants, when the oral pathway is open. It has no accepted meaning during a nasal consonant when the oral pathway is closed. The Glottal Enterprises software is the only system that allows you to exclude nasal consonants in an average reading by a mouse click. However some users may want to include the “nasalance” values recorded during speech sounds produced as a nasal consonant in a reading of average nasalance, as, for example, in extremely disordered speech or to compare the numbers obtained with values in the literature obtained using older systems that did not have the capability to eliminate nasal consonants. With the NAS-1 system you have a choice.
- Why does the Glottal Enterprises system for measuring nasalance have periods in the chart during which no nasalance is computed? There are no such gaps evident in the charts generated by some competing nasalance measuring systems.
Answer:
Nasalance should theoretically only be computed during voiced sounds in which the oral passageway is open. During periods in which there is little or no voice energy, such as the closure of a stop consonant such as /p/ or /b/, or during a fricative consonant such as /s/, /z/, /f/, or /v/, the software in the NAS system uses an acoustic threshold criterion to determine that there is no voiced vowel and does not compute nasalance. During nasal consonants, nasalance is computed, but identified by a change in color (to blue in the present version) so that the user can include or exclude values from average nasalance computations. It is important to realize that all nasalance measuring systems must have an acoustic threshold below which no nasalance is computed. In one popular system however, this threshold is not evident, since there are no gaps in the display. This is apparently caused by using a very long smoothing time, so that a gap is replaced with a dip in the nasalance value. The result is that the user cannot verify that the threshold was indeed set correctly (if it isn't, there will be an error in average nasalance computations) and the structure of the phrase or sentence will not be readily discernible. In the Glottal Enterprises nasalance system, the smoothing time is kept short enough so that the consonants and pauses are clearly identifiable.
- How does the Glottal Enterprises system for automatically marking nasal consonants work? Is it reliable for patients having a speech disorder?
Answer:
The theoretical basis for marking the approximate duration of a nasal consonant depends only on the presence of an oral closure and thus is valid for both normal and disordered speech. No judgment is made concerning the phonological intention of the speaker. As long as the oral passageway is open, the nasalance cannot rise above about 70% (assuming no strong obstruction in the nasal passages). When a complete closure of the oral passageway is approached (as in a nasal consonant), the nasalance will quickly rise above 70%. The NAS software identifies nasalance values above approximately 75% as being associated with an oral closure and, therefore, a nasal consonant. (If both nasal and oral passageways are closed, as in the closure of a stop consonant, both the nasal and oral energies will be small – that is, below threshold – and no nasalance value is computed.)
- Can the so-called SNAP test (Simplified Nasometric Assessment Procedure, as described by Ann W. Kummer in Cleft Palate and Craniofacial Anomalies, Singular Press, 2001) be used with the NAS-1 system?
Answer:
The SNAP test or its equivalent can be used on any device for displaying nasalance, including ours.
- Can systems for measuring nasalance be used for measuring nasal emission in pressure consonants?
Answer:
No. If a manufacturer claims that its nasalance system does measure nasal emission, it is a misstatement
- Can a system for measuring nasal emission in pressure consonants also measure nasal airflow in vowels?
Answer:
Yes, though perhaps not as conveniently as with a system measuring naslance.
Airflow/Air Pressure/Inverse Filtering
- Can the OroNasal mask be used to obtain separate simultaneous measures of nasal and oral airflow? If so, would such a display be useful for evaluating velopharyngeal insufficiency?
Answer:
Yes this is possible, though there are two interpretations to the question:
- In one interpretation, the airflow signals recorded would be the low frequency components that show the components of the breath-stream.
- In another interpretaion, the airflow signals recorded would be the acoustic components of the nasal and oral airflow.
Option 1 is possible, though it requires some significant instrumentation (appropriate pressure transducers, electronics to power the transducers and for preamplification, A-D conversion, and appropriate display software). We can supply most of what is needed. However, the separate low frequency signals are difficult to interpret during voiced speech and moreover contain jaw motion artifacts during continuous speech.
Option 2 is possible through our NAS-1 system, using any of a number of stereo audio editors, some, such as Audacity, in free shareware. Though the dual display is decidedly more difficult to interpret than the ratio measure displayed in the NAS-1 nasalance system, at least one university uses the dual display for research and teaching purposes.
- How do the Glottal Enterprises airflow and pressure calibrators work?
Answer:
The PC-1 supplies a fixed pressure, settable by the user, and monitored by a standard Magnehelic pressure gauge. The FC-1 uses a fixed, known air volume, and the airflow rate is computed from that volume by the software.
Electroglottograph
- Please describe the optional Fundamental Frequency Trigger Output of the EG2 electroglottograph.
Answer:
Using the EGG signal as input, the F0 OUTPUT generates a standard impulse for each glottal cycle, roughly synchronous with the glottal closure instant. It can be useful for teaching purposes, if recorded with any audio recorder and replayed, since it has only pitch information. It can also be useful for speech resynthesis or as the input to a pitch display. However, since there is no complex logic to eliminate the occasional pulse generated by vocal fold motions other than in voicing, a generalized F0 detection software program operating directly on the EGG signal may often yeild a more useful result.
- How can EGG signals be displayed, other than by using the Waveview software?
Answer:
Any software package that displays stereo audio can display EGG signals, or EGG and audio including free open-source audio editors such as Audacity. However, these programs will not supply the low frequency phase compensation for waveform correction that is in the Glottal Enterprises Waveview program.
- Why do some subjects show an EGG signal with more noise than others?
Answer:
Our EGG units are checked to have a noise level at least a factor of 100 (40 dB) less than a signal equivalent to a neck resistance change of 0.1 %. This level of resistance change is attained, or at least approached, in a typical adult male larynx and neck anatomy. However, with a typically smaller female or child larynx, and even with an adult male subject, if the larynx is deep into the neck muscle, fatty tissue, etc., the noise can be up to a factor of 10 (20 dB) higher. Therefore when recording from persons showing a weaker than average EGG signal, it is important to use electrode jelly, press the electrodes into the neck a little, and use the unit's electrode position meter to optimize the vertical position of the electrodes. Also, the anterior margins of the electrodes should be closely spaced, no more than about a centimeter apart.
As for low-frequency noise, the low-frequency limit in a PCX model could be optimally a little higher with the higher F0 of a female or child voice. (The low-frequency limit on the EG-2 model is adjustable, but the PCX value is set to 20 Hz.) An external high pass filter set at about 50 Hz can reduce the low frequency noise for a female or child voice without hurting the waveform significantly.
Also, the sensitivity of an EGG can make it susceptible to ambient electromagnetic noise from other electronic devices in the vicinity. This may show up only with subjects yielding a weak EGG signal. If you suspect that there is an external noise source, try recording in another location and/or moving the EGG unit further from the computer.
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