In this chapter speech technologies will be described from various perspectives: From the point of view of research and development, system use and quality experience, as well as quality measurement. This is not done to validate the relevance of the technology itself, but to authenticate the perspectives, demands, conditions, aims and limitations of voice and speech quality assessments by presenting facts. They establish a data-based approach to analytically review the status of speech quality measurements. Speech technology is introduced here as an instrument. The issue is not to give a state-of-the-art of speech technology but to explore in how far speech technology can be used to examine the fundamentals of voice and speech quality perception. In subsequent chapters different experiments are introduced where speech technology devices are the measurands; however, these experiments are a means themselves to exemplify which quality assessment processes can be observed and how they can be analyzed. It is not experimental data that are of interest primarily but processes of audition and judgment which lead to these data. In order to understand what these experiments are driving at it is useful to have a broad overview of voice and speech devices and their performance. Positioning speech technologies in their various contexts highlights the need to discuss voice and speech quality perception and to collect evidence that will justify the approach introduced here.