Development of an Intelligent Artificial Larynx

在第一年（1986年）对声门声源的语言、生理和声学特性进行初步调查的基础上，设计了人工喉头的生物信号检测、控制信号编译和声门声源产生三个部分，并于第二年（1987年）建立了它们的原型模型。然后，在第三年（1988年），将这些部分组装起来，在不进行手术的情况下对受试者进行实验设置，以评估综合特征。本项目提出的人工喉头作为喉切除患者的替代声源，其目的是提供自动控制语音浊音源主要参数的能力，如声源的启动和停止，在不浊音处声带振动的瞬间停止，以及语音基频和振幅对韵律信息的变化。对于声源的启动和停止以及声带振动的瞬间停止等参数，研究了通过专门设计的开关装置进行人工控制的可能性，同时研究了它们定时的基本性质。这个定时开关在实际阶段将被参与发声的肌肉的残余功能所取代。还确定了利用呼气气流控制由基频和振幅变化传递的韵律信息的可能性。根据第三年的实验结果，指出了人工咽机在语音质量、清晰度、使用方便、操作准确等方面存在的缺陷，并讨论了需要改进的地方。

Based on the preliminary investigation in the first year (1986) on linguistic, physiological and acoustical characteristics of the glottal sound source, three parts of the artificial larynx, namely, detection of biological signal, compilation of control signal and generation of glottal source, were designed and their prototype models were built in the second year (1987). Then, in the third year (1988), those parts were assembled to evaluate the combined characteristics in an experimental set up without surgical operation for the subjects.In the artificial larynx which is proposed in this project as an substitutive voice source for laryngectomized patients, it is aimed to provide capabilities of controlling automatically major paramenters of voiced sound source of speech, such as start and stop of voice source, instant stop of vocal fold vibration at unvoiced consonant, and changes in fundamental frequency and amplitude of voice for prosodic information.As for the start and stop of voice source and the instant stop of vocal fold vibration among those paramenters, possibility of manual control with a specially designed switch device was examined, at the same time, the basic nature of their timing was investigated. This timing switch is to be replaced in the practical stage by residual function of muscules involved in voicing. Possibility of controlling prosodic information conveyed by changes in fundamental frequency and amplitude by using expiratory airflow was also ascertained.As results of those experiments conducted in the third year, defects in the artificial alrynx regarding to quality and clearness of speech sound, easiness of use, and accuracy of operation were remarked, and points to be improved were discussed.