What the voicing of air from a mouth (without syllable) called? For example when we say the consonant "sh" without a syllable. It's usually happens when you want to quiet a child or something like that (it's almost like a whistling, but it's not exactly the same, or maybe it's a kind of whistling). In some cultures when one wonders on somethings bad or huge he may make such sound. I'm looking for the name for this sound.