Aeroview System

The Aeroview system for phonatory aerodynamics measures the ‘average glottal flow resistance’ during vowel production, Rg, and its reciprocal, the ‘average glottal flow conductance’, Gg., using an automated factory-optimized algorithm. The average glottal airflow and interpolated subglottal pressure used in the calculation are also displayed. Aeroview is a natural complement to Waveview, our program for analyzing glottal airflow waveforms by means of inverse filtering and simultaneous electroglottograph signals. As with Waveview, we have kept the user interface simple and intuitive, to make it useful for students as well as voice researchers. Lines on the Aeroview screen show the automated measurement procedure for each syllable measured, as in the following annotated figure, so that the user can easily spot measurement errors.

Other measures of voice quality, such as the Sound Pressure Level (SPL) and the Fundamental Frequency (F0) of the measured vowel segment phonation, and the Phonatory Threshold Pressure (PTP) can also be obtained.

Shows two transducers being used, one measures airflow, and one measures intraoral pressure when coupled to an OPA.

Rg and Gg are defined:

Rg = Average Glottal Airflow / Estimated Average Subglottal Pressure.
Gg = Estimated Subglottal Pressure / Average Glottal Airflow = 1/ Rg

To compute Rg , the program accepts as input:

1. the airflow signal from a circumferentially vented (CV) pneumotachograph mask and matching pressure transducer, and
2. the intraoral pressure, as measured by a catheter between the lips connected to a pressure transducer.

To compute Rg, the subject produces a series of /p Vowel/ syllables, as “pa pa pa pa pa”, or /b Vowel p/ syllables, as “bap bap bap bap bap”. The subglottal pressure during each vowel is interpolated from the oral pressure peaks during /p/ consonants preceding and following the vowel.  This procedure was introduced in a 1973 paper by M. Rothenberg, (A new inverse-filtering technique for deriving the glottal air flow waveform during voicing, J Acoustic Society of America 53, 6, 1632 - 1645, and first applied to clinical voice evaluation by Smitheran and Hixon (A clinical method for estimating laryngeal airway resistance during vowel production. J. Speech and Hear. Dis. 46, (1981), 138-146).

Note:  The pressure transducer used for airflow is preferably a Glottal Enterprises PT-2E (formerly PTW) wideband model.  If a narrow-band pressure transducer is used (PT-2 or equivalent), Rg and Gg will be recorded properly, but the Sound Pressure Level (SPL) recorded may not be accurate and the sound on Playback will be degraded.  The transducer for intraoral pressure may be either a PT-25, for pressures to 25 cm(H₂O), or a PT-75 for if pressures above 25 cm(H₂O) are expected, as in some singing applications. A PT-25 should be adequate for all speech applications.

The program is designed to work as a turnkey system with the appropriate Glottal Enterprises masks, transducers and calibrators and the MS-110 transducer interface electronics unit.  The MS-110 can provide the needed analog to digital conversion and uses a computer’s USB input jack. However, an MS-100 system (which does not have the A-D capacity) can be used with any third-party multichannel A-D system that can produce a standard stereo WAV-file format.

An important feature of the Aeroview program is that the approximate syllable rate is automatically computed by the program and displayed on-screen. This allows the clinician to eliminate syllable sequences which were pronounced outside the optimal 2.5/second to 4.0/second range. (A syllable rate significantly higher than 4/sec may yield pressure pulses in which the subglottal and oral pressures have not equalized, or a vowel that does not have a quasi-steady-state segment that can be measured. (Note that in Figure 1 the airflow only briefly attains a steady-state before increasing, as the vocal folds abduct for the following /p/.  The syllable rate was approximately 4.1 per second.  A rate significantly slower than 2.5/sec may result in the subject not holding the subglottal pressure constant over the syllable, but producing a separate increase of pressure for each syllable and a decrease between syllables.  This type of pronunciation may not allow an accurate extrapolation of subglottal pressure.)

The Aeroview system for phonatory aerodynamics is available as AeroviewPro and AeroviewPlus. AeroviewPro provides the standard measurements of phonatory aerodynamics, as described above. AeroviewPlus consists of the AeroviewPro system bundled with the Waveview program for obtaining the glottal waveform by inverse filtering.

AeroviewStudent Software

To make the Aeroview program available to students as an instructional tool, as well as provide a thorough evaluation package for prospective purchasers, Martin Rothenberg has also developed the AeroviewStudent interactive instructional program that includes most of the capabilities of the full version, except for the capability to record new waveforms, plus a number of carefully selected prerecorded waveforms of simultaneous oral airflow and intraoral pressure. AeroviewStudent is available from Glottal Enterprises at low cost on a CD that also contains a detailed 10-page Exercise Manual  The steps in this interactive manual use the prerecorded waveforms to enable the user to learn the operation of the analysis functions of Aeroview and the interpretation of the results for normal and disordered voice qualities.