Both approaches are suitable for the generation of spoken language corpora (cf. Chapters 3 to 5): while flawless speech may be sufficient for allround utilisation, a collection of in-car speech at certain conditions (car speed, road surface, etc.) may be highly valuable for the example given above, but is restricted to this special case. In both the ideal and the real-life approaches, a detailed protocol of all recording conditions is mandatory (cf. Section 8.7 on reproducibility ).
In designing speech assessment environments, we can find a similar distinction between field and laboratory tests (cf. Chapter 12). While a field test is executed in a real (natural or virtual) environment, laboratory tests with subjects may utilise both clean and real-life speech. For speech output assessment in case of speech synthesisers or codecs, the ``clean'' output speech has to be subsequently adopted to real-life conditions by signal processing steps (cf. Section 8.8).