Initial affricates and fricatives become final plosives. Labiodental consonants are most often fricatives while labiodental nasals are also typologically common. A number of languages have syllabic fricatives or fricative vowels. Voiceless approximants are rarely distinguished from voiceless fricatives. Basque has a distinction between laminal and apical articulation for the alveolar fricatives and affricates. Geminate fricatives, nasals, and are realized as lengthened continuants. The voiced alveolar fricatives are consonantal sounds. The opposite process happens with fricatives, affricates, laterals and trills. It has retained the Old Norse dental, velar and labial voiced fricatives. Doubled consonants are geminated; the geminate fricatives /, and cannot be voiced. A particular subset of fricatives are the sibilants. Most have no fricatives at all or only the fricative . The uvular fricatives and are commonly spelled and . However, phonemically aspirated fricatives are rare. A broader category is stridents, which include more fricatives such as uvulars than sibilants.