A device that monitors the vibration of the human vocal folds in the larynx during speech. As the vocal folds vibrate they come into contact and peel apart regularly once per cycle. Two electrodes are placed externally at the level of the larynx, one either side of the neck. A high-frequency (1–3 MHz) constant-voltage signal is applied to one electrode and the interelectrode current-flow waveform is output; this is known as an electroglottogram (EGG). The nature of vocal-fold vibration during normal and pathological speech as well as singing can be studied from the electroglottogram.