关键词:
Nonlinear oironits
audio systems
real-Lime systems
circuit simulation
computer generated music
摘要:
This thesis addresses the use ofcircuit modeling teohnioues in audio. Circuit modeling has a wide range ofapplications in audio, inoluding l'eal-time models ofanalog electronic audio equipment and the use ofphysical analogies for understanding and simulating musioal instru- ments. Modeling ofanalog audio equipment is an important topic in audio signal processing. it enahles the development ofmusical soawaie that is capable of simulating rfile vintage equip- ment at a low oost. This type orsostwaie can be embedded in portable electronic equipment, in mobile phones 01' tablets, OI in computers. This thesis presents novel models ofanslog audio equipment used with guitars. It presents a nonlinear audio-transformer model which is used for real-time emulation ofvacuum-tube guitar amplifiers. This model has shown that some audio transformers have nonlinear effects for input signals with frequencies below 100 Hz. A new wave-digital model for operational amplifiers is proposed, which is used to simulate a wide class ofguitar distortion circuits. The same distortion circuits were modeled with a novel method based on nonlinear system identi- fication, which is enhanced using principal component analysis (PCA) for reduced complexity. It was shown that the proposed method reduces the complexity of the polynomial-Hammer- stein model obtained with the swept-sine technique by S6 %, Additionally, electromagnetic pickups were analyzed and modeled, leading to new pickup~mixing and nonlinearity models and to a better understanding on the effects ofguitar pickup and cable interaction, This thesis has also presented how to use physical analogies for audio synthesis. Electro-acous- tic analogies were used in order to obtain a model of connected Helmholtz resonators, resulting in the so called Helmholtz resonator tree. This model was implemented using wave-digital filters, which enables musical synthesis using physical descriptors that are intuitive also for non-technical users, This thesis inc