Transient Models

Another improvement to sines+noise modeling in the late 1990s was explicit transient modeling [6,149,147,144,148,290,282]. These methods address the principal remaining deficiency in sines+noise modeling, preserving crisp ``attacks'', ``clicks'', and the like, without having to use hundreds or thousands of sinusoids to accurately resynthesize the transient.^G.13

The transient segment is generally ``spliced'' to the steady-state sinusoidal (or sines+noise) segment by using phase-matched sinusoids at the transition point. This is usually the only time phase is needed for the sinusoidal components.

To summarize sines+noise+transient modeling of sound, we can recap as follows:

• sinusoids efficiently model tonal signal components
• filtered-noise efficiently models the what's left after removing the tonal components from a steady state spectrum
• transients should be handled separately to avoid the need for many sinusoids

So, although sinusoids are sufficiently general thanks to Fourier's theorem the combination of sines, filtered-noise, and transient segments can provide a much more compact basis for audio signals. Such compact building-blocks for sound are useful for audio coding and manipulation.