Fortis and lenis

Are b, d, g voiced plosives? The description of them makes it clear that it is not very accurate to call them "voiced"; in initial and final position they are scarcely voiced at all, and any voicing they may have seems to have no perceptual importance. Some phoneticians say that p, t, k are produced with more force than b, d, g, and that it would therefore be better to give the two sets of plosives (and some other consonants) names that indicate that fact; so the voiceless plosives p, t, k are sometimes called fortis (meaning 'strong') and b, d, g are then called lenis (meaning 'weak'). It may well be true that p, t, k are produced with more force, though nobody has really proved it - force of articulation is very difficult to define and measure. On the other hand, the terms fortis and lenis are difficult to remember. Despite this, we shall follow the practice of many books and use these terms.

The plosive phonemes of English can be presented in the form of a table as shown here:

Tables like this can be produced for all the different consonants. Each major type of consonant (such as plosives like p, t, k, fricatives like s, z, and nasals like m, n) obstructs the airflow in a different way, and these are classed as different manners of articulation.