This laboratory assignment should teach the student how to model the physics of a plucked vibrating string using a digital waveguide. First, physical models and their applications are explained. Next, the vibrating string is introduced as an example of a finite-length waveguide with inverting reflections. The traveling wave decomposition of the vibrating string is sampled to derive the digital waveguide model. A lowpass filter is added to the model's feedback loop to increase modeling accuracy.
The student then ``plays'' the digital waveguide string simulator in pd. At first the student is free to adjust conveniently-formulated model parameters. Then, using a second, more elementary pd patch, the student adjusts the digital waveguide's parameters directly. This final step ensures that the student understands the operation of the digital waveguide model.
