Summary: Most musical instruments as well as the human voice create sound by exciting a resonant structure or cavity by a wideband pulsed source. The resonant structure amplifies select frequency bands (called formants) and suppresses (or "subtracts") others. Subtractive synthesis algorithms use time-varying sources and time-varying digital filters to model physical instruments. Learn how to use the DSP capabilities of LabVIEW to implement an interactive time-varying filter, a band-limited wideband source, a vowel synthesizer for speech, a "cross synthesizer" in which a speech signal's spectral envelope is superimposed on a musical signal, and a remarkably life-like plucked string sound. This course is part of the series "Musical Signal Processing with LabVIEW".