Voiceless alveolar fricative

A voiceless alveolar fricative is a type of fricative consonant pronounced with the tip or blade of the tongue against the alveolar ridge (gum line) just behind the teeth. This refers to a class of sounds, not a single sound. There are at least six types with significant perceptual differences:
 * Voiceless alveolar "hissing" sibilant, with a strong hissing sound, as in English sin. One of the most common sounds in the world because of its highly piercing, prominent sound (hence its use to get people's attention, as in "ssssst!").
 * Voiceless "apico-dental" "lisping-hissing" sibilant (an ad-hoc notation), with a weaker hissing sound reminiscent of the "lisping" English th fricative.  Commonly heard in the Spanish spoken in a band of territory in southern Spain, arcing through Andalusia from the southwest to the north to the southeast.
 * Voiceless "apico-alveolar" "grave" sibilant, with a weak "hushing" sound reminiscent of fricatives.  This sound is well known from the languages of northern Iberia, like Astur-Leonese, Basque, Castilian Spanish, Catalan, Galician and Northern Portuguese.
 * Voiceless alveolar non-sibilant fricative or, using the alveolar diacritic from the Extended IPA. This sounds somewhat like the th in English thin.  Occurs in Icelandic.
 * Voiceless alveolar rhotic fricative . This sounds like a voiceless, strongly articulated version of English r (somewhat like what the English cluster hr would sound like).  Occurs in Edo, a language spoken in Nigeria.
 * Voiceless alveolar lateral fricative . This sounds somewhat like a voiceless, strongly articulated version of English l (somewhat like what the English cluster hl would sound like).  Occurs in Welsh words with ll.

The first three types are sibilants, meaning that they are made with the teeth closed and have a piercing, perceptually prominent sound.