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Diagnosing
vocal pathologies
The research standard for noninvasive measurement of vocal fold vibration. |
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The Glottal Enterprises electroglottographs produce very low-noise EGG waveforms and have the features most requested by researchers and clinicians. The patented dual-channel configuration of both the EG2 and EG2-PCX enables them to indicate proper electrode placement and provide a quantitative indication of vertical laryngeal movement. The EG2-PCX model offers easy connection to a personal computer for use with today's popular speech software packages. The EG2 electroglottograph provides a high degree of flexibility in setting the response time and output signal level for demanding research applications. |
 Measurements of the signal-to-noise ratio made using the LS-1 Larynx Simulator and a comparison to the EGG unit marketed by other manufacturers, can be seen here. |
EG2-Standard
Optional EG2 Back Panel:
EG2-PCX
EG2-PCX Back Panel:
Key benefits:
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Behringer ECM 8000 Omnidirectional Microphone
 XLR Wires |
The ECM8000’s linear frequency response and omnidirectional polar pattern allows you to carry out measurement and alignment tasks with minimum hassle and maximum precision.
LS-1 Larynx Simulator and C-1 Phase Compensator
 LS-1 Larynx Simulator |
 C-1 Phase Compensator |
Glottal Enterprises is pleased to announce the availability of a calibrator for its line of electroglottographs. The LS-1 larynx simulator plugs into the neck-lead jack of any Glottal Enterprises EG series electroglottograph, in place of the electrode cable, and provides an electrical simulation of the small variation of neck resistance being measured by an electroglottograph during voice production. The LS-1 is useful for measuring and verifying the performance of the unit, and providing objective inter-unit comparisons.
The simulated variation of neck resistance produced by the LS-1 was chosen to maximize its usefulness in estimating the high and low frequency responses from the resulting EGG waveform and measuring the signal-to-noise ratio of the EGG and other processing systems employed. The LS-1 works with both single-channel and dual-channel electroglottographs and will also check the functioning of the electrode placement / laryngeal height display when used with a dual channel unit.
The LS-1 can also be used with the Glottal Enterprises C-1 phase compensator to correct the waveform for the phase distortion introduced by high-pass filtering, as when using the audio board of a PC for data acquisition.
Technical Details
The LS-1 simulates a neck resistance of 150 Ohms between the electrodes of each EGG channel – a typical value – that varies 0.1% at a frequency of about 200 Hz, with a duty cycle of approximately 60% (vocal folds apart during 60% of the glottal period). A resistance variation of 0.1% represents a typical variation in neck resistance during voicing, and is roughly an average between the values of 0.3 to 0.5% found with subjects having a very strong EGG signal and the values of about five times less than 0.1% found with subjects having a very weak EGG signal. The duty cycle chosen is convenient for checking measures of vibratory duty cycle made from the EGG waveform and for enabling the user to verify the polarity of the waveform (whether an increase in vocal fold contact area corresponds to an increase or decrease in EGG waveform).
The simulated vocal fold vibratory frequency of 200 Hz was chosen to make system frequency response factors easily judged from the resulting EGG waveform. The variation of neck resistance simulated by the LS-1 is essentially instantaneous between the simulated glottal open and closed phases, so that the high frequency response can be judged from the rise and fall times of the resulting trace, and the low-frequency amplitude and phase response can be judged from the slope and shape of the trace during the simulated glottal open and closed periods. (For a perfect low frequency response, the slope during each period would be negligible.)
When used with the C-1 compensator, the simulator’s EGG trace can also be used to correct EGG recordings for a degradation in low frequency response caused by software after recording, or by analog circuitry before recording. The C-1 compensator is an analog device that can be used for this purpose. It is easily inserted between the EGG and the recording or display system, and reduces the phase distortion introduced by high pass filtering by a factor of three or more.
The LS-1 operates on an internal 9-volt alkaline battery, which in normal use should last a number of years, or close to the shelf life of the battery. A battery is supplied with the unit. The C-1 requires no power.
Adapter cables that allow the LS-1 or C-1 to be used with older models of Glottal Enterprises electroglottographs or most electroglottographs sold by other manufacturers can be provided at additional cost. Please inquire for a price quote.
Glottal
Enterprises |
