Fortis and lenis

In linguistics, fortis (/ˈfɔːrtɪs/ ^ⓘ FOR-tiss; Latin for 'strong') and lenis (/ˈliːnɪs/ ^ⓘ, /ˈlɛnɪs/ LEE-niss, LEN-iss; Latin for 'weak'), sometimes identified with 'tense' and 'lax', are pronunciations of consonants with relatively greater and lesser energy, respectively. English has fortis consonants, such as the p in pat, with a corresponding lenis consonant, such as the b in bat. Fortis and lenis consonants may be distinguished by tenseness or other characteristics, such as voicing, aspiration, glottalization, velarization, length, and length of nearby vowels. Fortis and lenis were coined for languages where the contrast between sounds such as 'p' and 'b' does not involve voicing (vibration of the vocal cords).

Originally, the terms were used to refer to an impressionistic sense of strength differences, though more sophisticated instruments eventually gave the opportunity to search for the acoustic and articulatory signs. For example, Malécot (1968) tested whether articulatory strength could be detected by measuring the force of the contact between the articulators or of the peak pressure in the mouth. Because such studies initially found little to substantiate the terminology, phoneticians have largely ceased using them, though they are still commonly used as "phonological labels for specifying a dichotomy when used language-specifically." This can be useful when the actual articulatory features underlying the distinction are unknown, under-researched or irrelevant.

Later studies have shown that articulatory strength is not completely irrelevant. The articulators in the mouth can move with a greater velocity and/or with higher electromyographic activation levels of the relevant articulatory muscles with fortis consonants than with lenis ones.

Generally, voiceless stops have greater oral pressure than voiced ones, which could explain this greater articulatory energy. In Ewe, for example, the lips reach closure faster in articulating /p/ than in /b/, making the lip closure longer. These differences in oral articulatory energy in consonants of different laryngeal settings is fairly widespread, though the correlation of energy and voicing is not universal. Indeed, a number of languages have been proposed as making strength differences independently of voicing, such as Tabasaran, Archi, Udi, and Aghul.

It is rare for the use of greater respiratory energy for segments to occur in a language, though some examples do exist, such as Korean, which makes a three way contrast amongst most of its obstruents with voiceless, aspirated, and a third faucalized voiced set that involves both an increase in subglottal pressure as well as greater glottal constriction and tenseness in the walls of the vocal tract. Igbo has also been observed to utilize an increase in subglottal pressure involving its aspirated consonants.

"Fortis" and "lenis" have also been used to refer to contrasts of consonant duration in languages like Jawoyn, Ojibwe, Dalabon, Kunwinjku, and Zurich German. The Zapotec languages are also considered to have contrast of length rather than of voicing. For example, in Mixe, lenis consonants are not only pronounced shorter than their fortis counterparts, but they are also prone to voicing in voiced environments, which fortis consonants are not.

This association with longer duration has prompted some to propose a diachronic link between fortis consonants and gemination. Payne (2006) even proposes that gemination is itself a process of fortition in Italian.

Many North Caucasian languages (Northwest and especially Northeast) have a consonantal distinction described as "strong" or "preruptive" that has concomitant length. Akhvakh and other Northeast Caucasian languages even possess a distinction between strong/long and weak/short ejective consonants: [qʼaː] ('soup') vs. [qʼːama] ('cock's comb')