One of the most fundamental constructs of phonological theory past and present is ‘neutralization’, i.e. the merger of a contrast in certain contexts. It is as basic as such other constructs as ‘contrast’, ‘distinctive feature’, and ‘segment’. While there exists a substantial body of literature on the phonetics of various phonological constructs (e.g. acoustic correlates for features, acoustic invariance, descriptive phonetics of particular languages, instrumental measurement techniques and segmentation criteria), the phonetics of neutralization has largely been assumed on the basis of casual impressionistic phonetics. The assumption is that forms which are distinguishable phonetically and phonologically in certain contexts and/or levels of representation (e.g. intervocalic voiced and voiceless obstruents in German) are under certain other well-defined circumstances totally indistinguishable at the level of phonetics (e.g. only voiceless obstruents occur word-finally in German).