The volume velocity waveform of the air flow through the larynx during voiced speech is a good indicator of the vibratory pattern of the vocal cords (or vocal folds), especially if the average lung pressure is also known. Though this air flow is difficult to measure directly, it can be inferred from the pattern of air flow or pressure in or near the mouth, by a process known as "inverse filtering." However, an inverse filter requires a knowledge of the transmission characteristics of the vocal trac between the larynx and the mouth (or from the larynx to the pressure/flow sensor used) and therefore is difficult to apply in many clinical situations. This proposal describes a relatively simple and robust method for processing a waveform of the air flow at the mouth so as to produce a clinically-useful representation of the laryngeal flow that does not requires a high level of training to implement. It is proposed that the method be implemented on a microcomputer and compared with accurate invers filtering for a variety of normal and abnormal voice qualities.National Institute of Neurological Disorders and Stroke (NINDS)
