Pronunciation GB: ləˈrɪŋɡəɡrɑːf, GA: ləˈrɪŋɡəɡræf

An electronic device for monitoring and analysing the vibratory activity of the vocal folds. It operates by passing a weak electric current between two electrodes placed externally on either side of the speaker’s neck at the level of the thyroid cartilage. The electrical impedance of the neck is measured by the device. As this impedance varies as the vocal folds vibrate, the output of the device is a signal analogous to the degree of vocal fold contact at a given instant. This waveform of impedance against time is known as Lx. Lx may be further processed to derive information about the duration of the period of vocal fold vibration (Tx) and to measure instantaneous fundamental frequency (Fx).

A sequence of stroboscopic images of one cycle of vibration of the vocal folds aligned with the resulting Lx signal