Electroglottography - the Research Standard for Noninvasive Measurement of Vocal Fold Vibration and Assessment of Laryngeal Function
Electroglottography provides laryngographic assessment of phonatory function during connected speech, soft and loud singing. It gives qualitative and quantitative information about the contact, separation and open phase of vocal fold vibration and is therefore of great use in the interpretation of pathological conditions and follow-ups after surgical treatment or conservative voice therapy. It has proved particularly useful in assessment and documentation of organic voice disorders.
The key benefit of electroglottography is a direct non-invasive measurement of vocal fold vibration without interfering in the normal processes of speaking and singing.
Before each new laryngographic examination of vocal fold vibration two electrodes are placed on the subject's neck at the level of the thyroid cartilage. The laryngograph detects variation in the electrical resistance of the current passed between the electrodes. The resistance is produced by changes in the nature and area of vocal fold contact during phonation. The electrolaryngographic output from the speaker's voice activity is displayed as a laryngograph waveform showing horizontal opening and closing movements of the vocal folds. Many of commercially available devices make it possible to record an additional signal (sound pressure waveform) from a microphone, which is synchronized with the laryngographic output, so that both waveforms can be directly compared when displayed one on top of another.
The lingWAVES EGG module fits seamlessly into the modular lingWAVES speech software package. It can be added as an upgrade to existing lingWAVES modules (eg. lingWAVES Phonetogram Plus, lingWAVES Voice Diagnostic Center (VDC)) or, if purchased as a new system, it can be enhanced by the addition of further software modules. lingWAVES users will definitely benefit from working with a uniform and familiar software user interface for clinical voice analyses.
Two channel recording of voice and EGG signal
Period-by-period analysis also possible for recordings or in real time.
The new EGG multi-parameter module allows for instantaneous processing of laryngograph and speech waveform data as well as multi-dimensional voice analysis at the push of a button. The module has all the important quantitative acoustic analyses most requested by clinicians, researchers and practitioners in daily practice. The available analyses build up a multi-dimensional voice profile that is presented on a complex display and can be printed for filing.
Opening and closing movements of vocal folds and optionally real-time display of acoustic (sound pressure) waveform, optional marking of open phases under zoom magnification and Analysis Open Quotient.
Open quotient is defined as the ratio between glottal open time and fundamental period. Displays available: Lx-waveform display with marked open phases, display of open quotient distribution in a speech sample, display of a plot of open quotient against fundamental frequency.
Jitter results from cycle to cycle variations of the fundamental frequency and is calculated as the mean period to period variation in the residual fundamental frequency values.
Cross plot contains information on the period to period differences in regards to frequencies. The graph on the down left shows Frequency 1 against Frequency 2, where Frequency 1 is the frequency value of the first vocal fold period in any pair of periods and Frequency 2 is the frequency value of the immediately following period of the pair. Regular vocal fold vibration (left) gives a clearly defined diagonal line since successive periods have almost the same values. For the pathological voice, the shape of a crossplot is more diffuse than is the case with normal speakers as the range of variability in period to period coherence is not under the speaker's control. The graph on the down right shows vocal fold frequency distribution (pitch range histogram), i.e. the range of frequencies contained in a sample.
Provides an insight on the period to period differences in regards to amplitudes. The amplitude of one laryngeal vibration is plotted against that of the next vibration. There is little deviation from the ideal diagonal line distribution for the good normal voice.
Display: All analyses can be variably displayed and printed for filing.
The lingWAVES EGG comes with the best available EU medical product certified EGG hardware on the market. In cooperation with Laryngograph Ltd. we offer a high quality standard for hard- and software.
Windows 7, 8.1, 10 (32/64), min. 4 GB RAM, 500 GB hard drive, one free USB port.