The word sibilance is used to describe a particular type of sound centered around 7 kHz that occurs most often in vocals when the consonants "s", "st", and "ch" etc. are pronounced producing a high pitched tone that is heard as hissing. Sibilance is something that all sound engineers must deal with in vocal recordings as these sounds are quite often much louder then the rest of of the vocal track and are interpreted as an unpleasant tonal harshness.<br>