ASPIRE Evo from Antares is a plug-in tool for modifying a voice's breathiness independently of its harmonic content. It can be used to reduce a bit of vocal rasp, or to add a bit of "smokiness" to a vocal performance, without otherwise affecting the vocal's harmonic characteristics.
When you speak or sing, air from your lungs is forced through the vocal chords, causing them to vibrate. The resulting waveform is propagated through the throat, the mouth and out through the lips. It is the shape of these structures that create the resonant characteristics that define a unique vocal identity.
The vocal waveform is actually a combination of two different components. The first is the primary element of vocal timbre, the harmonic content. However, there is a second component that is generated by the turbulence of the air rushing past the vocal chords. This component, aspiration noise, does not have harmonic content and can roughly be thought of as "breathiness".
Aspiration noise presents itself in a variety of ways, from a subtle bit of breathiness to a full-blown rasp. Functioning as an Audio Units, RTAS or VST plug-in for Mac OS X or Windows based audio software, ASPIRE Evo makes it possible to enhance or attenuate this second component of the vocal waveform, either for corrective or creative purposes.