ABSTRACT
For the past two centuries or more, devices capable of generating artificial or synthetic speech have been developed and used to investigate phonetic phenomena. Early systems built in the late 18th and early 19th centuries were mechanical constructions whose components essentially formed a simulation of the human larynx and vocal tract. They served as a demonstration that speech production could be understood as a physical system, a concept that was largely hypothetical at the time. In addition, the modest success of these devices to synthesize artificial, but humanlike speech gave promise that, with adequate control, a machine could potentially be used to “talk” for persons with speech impairments.
In the early to mid-20th century, the advent of electrical systems brought about a major change in synthetic speaking devices. Using combinations of circuit elements as analogies to mechanical structures, or to form filters, allowed for greater complexity and more flexible control of the characteristics of speech. During this period, speech synthesizers based on filter banks, resonators, or transmission lines, along with the development of the sound spectrograph, were used to investigate many aspects of speech production and perception.
The course of speech synthesis was altered again with digital technology. No longer did synthesizers need to be “built” as real physical machines or with racks of electrical equipment. The entire synthesizer could now be realized as an algorithm with computational instructions. While many digital synthesizers are essentially computational versions of the electrical synthesizers, algorithms allowed for remarkable improvements, enhancements, and new ways of synthesizing speech.
This chapter provides a brief history of synthetic speech systems, including mechanical, electrical, and digital types. The primary goal, however, is not to reiterate the details of constructing specific synthesizers but rather to focus on how various synthesis paradigms have facilitated research in phonetics.
