Download Conformal Maps for the Discretization of Analog Filters Near the Nyquist Limit We propose a new analog filter discretization method that is useful
for discretizing systems with features near or above the Nyquist
limit. A conformal mapping approach is taken, and we introduce
the peaking conformal map and shelving conformal map. The proposed method provides a close match to the original analog frequency response below half the sampling rate and is parameterizable, order preserving, and agnostic to the original filter’s order
or type. The proposed method should have applications to discretizing filters that have time-varying parameters or need to be
implemented across many different sampling rates.
Download Neural Net Tube Models for Wave Digital Filters Herein, we demonstrate the use of neural nets towards simulating multiport nonlinearities inside a wave digital filter. We introduce a resolved wave definition which allows us to extract features from a Kirchhoff domain dataset and train our neural networks directly in the wave domain. A hyperparameter search is performed to minimize error and runtime complexity. To illustrate the method, we model a tube amplifier circuit inspired by the preamplifier stage of the Fender Pro-Junior guitar amplifier. We analyze the performance of our neural nets models by comparing their distortion characteristics and transconductances. Our results suggest that activation function selection has a significant effect on the distortion characteristic created by the neural net.
Download Distributed Single-Reed Modeling Based on Energy Quadratization and Approximate Modal Expansion Recently, energy quadratization and modal expansion have become popular methods for developing efficient physics-based
sound synthesis algorithms. These methods have been primarily
used to derive explicit schemes modeling the collision between
a string and a fixed barrier. In this paper, these techniques are
applied to a similar problem: modeling a distributed mouthpiece
lay-reed-lip interaction in a woodwind instrument. The proposed
model aims to provide a more accurate representation of how a musician’s embouchure affects the reed’s dynamics. The mouthpiece
and lip are modeled as distributed static and dynamic viscoelastic
barriers, respectively. The reed is modeled using an approximate
modal expansion derived via the Rayleigh-Ritz method. The reed
system is then acoustically coupled to a measured input impedance
response of a saxophone. Numerical experiments are presented.