The terms ‘tenues’ and ‘mediae’ have traditionally been used to denote the series of obstruents (= true consonants) associated with the letters p, t, k, s, etc. and b, d, g, z, etc., respectively.
From the phonological point of view, tenues and mediae subsume two distinctive features in terms of which they can be opposed: voiced vs. voiceless and tense vs. lax. The distinctive feature voiced vs. voiceless presents, from a logical viewpoint, two contradictory opposites whose physical counterparts are the presence vs. absence of glottal vibrations. A distinctively voiced media is thus normally constituted by the corresponding tenuis with superimposed glottal vibrations. Since voicing and tenseness are syncategorematic features, there obtains a normal complementary distribution of their physical correlates such that, in languages with distinctive voicing (like Russian), voiced obstruents are phonetically lax and voiceless ones phonetically tense. At the same time, in comparison to languages (like English) which have distinctive tenseness, languages evincing distinctive voicing manifest tenues which are normally relatively lax and tenuis stops which are relatively unaspirate (aspiration being a concomitant of distinctive tenseness, not voicelessness).
The distinctive feature tense vs. lax, on the other hand, is composed of two contrary opposites––greater vs. lesser protensity––typically implemented as a difference between tenues and mediae in the relative duration of the release portion and the tenure portion.
Despite the availability of a rich phonetic literature since at least the time of the pioneering English phonetician Henry Sweet (1845-1912), contemporary phonologists (including those of the generative stripe and their offshoots) have continually vacillated in their interpretation of English tenues and mediae, with the voiced vs. voiceless feature posited as distinctive more often than not. The great Russian phonologist Nikolai Trubetzkoy (1890-1938) even claimed in his Principles of Phonology that it is “impossible to say whether in English a correlation of tension or a correlation of voice is present.”
A refutation of this latter view is implicit in the several earlier posts (vide infra) where the theory of phonology underlying the analysis reposes on the fundamental principle that the sound system of a language is a semeiotic, a system of signs. Once the semiotic workings of the system are charted, using phonological implementation rules as a sign of the underlying hierarchy defining the sounds (phonemes), the membership of English in the typological group of languages (e.g., Japanese, Latin, Ukrainian, etc.) evincing protensity and not voicing in their tenues and mediae becomes irrefutable.