Audio effects

Overview

• Comb filters
• Harmonic Distortion
• Amplitude Modulation
• Vocoder

Feedforward

$$y[n] = x[n] + \alpha x[n-K]$$$$h[n] = \delta [n] + \alpha \delta[n-K]$$

Feedback

$$ y[n] = x[n] + \alpha y[n-K] $$

Flanger

A flanger is a comb filter whose delay $K[n]$ slowly oscillates within some range $\pm R$

$$y[n] = x[n] + \alpha x\left[n-K[n]\right]$$$$K[n] = R \cos(\omega_{\text{flanger}}) + \frac{R}{2}$$

Harmonic Distortion

Modeling speech

Vocoder