Abstract: The profoundly deaf benefit in lipreading if the larynx frequencies of speech are presented to them by means of acoustic sine waves. In the present invention the sine waves required are generated using a microcomputer and analogue output circuits, with the microcomputer providing digital level samples for the required sine waves from a stored look-up table. The wide frequency range of sine waves required is achieved by omitting some samples in each cycle at high frequencies, and the wide range of output levels required is provided by employing two digital to analogue converters, one acting as an attenuator.

Abstract: Apparatus primarily for stimulating the auditory nerve in the vicinity of the cochlea of deaf persons to give a sensation indicative of the pitch of speech is described. The stimulus which is in the form of an alternating current of varying period dependent on the pitch of speech is applied to an electrode positioned in the vicinity of the cochlea. The current is non-zero for most of the duration of most stimulation periods and in order to elicit a stable auditory sensation d.c. baseline fluctuation is prevented by the use of a controlled current generator. The period of speech sounds is found using a specially devised circuit and a voltage related to the frequency of such sounds is determined by a period-to-voltage converter and a reciprocal circuit, this voltage being supplied as a control signal for the current generator. An alternative microcomputer version is also described.

Abstract: The invention relates to the monitoring, recording and display of a speaker's larynx waveform, for the purposes of education, speech therapy and speech analysis. A pair of electrodes are applied externally to the larynx region of the speaker's neck. Each electrode has two concentric surfaces (the outer surface is called a guard ring). One electrode feeds a carrier voltage to the speaker's neck. The other electrode receives the resultant larynx amplitude-modulated current. Detection techniques are used to derive the larynx waveform. A preferred detection technique is "slicing" which is herein defined as a demodulation which follows the changes in envelope of an amplitude-modulated carrier and retains only the small rapid larynx modulation filtering out the slower neck-movement modulation. The important feature of speech called intonation, which is made up of rhythm and pitch patterns, is directly correlated with larynx frequency.