The objective of this thesis was to study and develop ways to digitally enhance the timbre of guitar pickup signals. The basis for this work was natural sounding reinforcement of an undersaddle pickup signal. A problem typically encountered in a live performance situation is that the microphones often used in acoustic guitars do not capture the effect of the hollow body of the acoustic guitar. As a consequence, the audible timbre of the microphone output sounds unnatural, compared to the air-radiated sound. A solution to this problem is to use a properly designed digital filter. A proper digital filter is able to synthesize the effect of a hollow guitar body to the undersaddle pickup signal. First, this thesis discusses the behaviour of the acoustic and electric guitar, and microphones typically used in them. Based on this, the signal paths of the system are described.
Thereafter, the modeling methods, techniques, and measurement setups are described as used in this work to synthesize the hollow body of a guitar. Different ways to realize the modeling digital filters are discussed, with some further issues related to the subject. Finally, the work describes the results obtained, and discusses possible future work plans. The methods discussed in this work are able to model the characteristic of a hollow guitar body. The modeling schemes can be used for acoustic guitars with an undersaddle pickup. In addition, the electric guitar can be filtered to sound more like an acoustic guitar. The perceived size of the modeled body can also be changed, i.e., a small-bodied guitar can be made to sound like a large one, and vice versa. The way this is implemented enables the use of the modeling filter as a time-varying sound effect.
Acoustic Timbre Enhancement of Guitar Pickup Signal with Digital Filters