Amplified guitars with pickups tend to sound ’dry’ and electric, whether the instrument is acoustic or electric. Vibration or pressure sensing pickups for acoustic guitars do not capture the body vibrations with fidelity and in the electric guitar with magnetic pickups there often is no resonating body at all. Especially with an acoustic guitar there is a need to reinforce the sound by retaining the natural acoustic timbre. In this study we have explored the use of DSP equalization to make the signal from the pickup sound more acoustic. Both acoustic and electric guitar pickups are studied. Different digital filters to simulate acoustic sound are compared, and related estimation techniques for filter parameters are discussed.

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This paper presents a high-quality real-time pitch-shifting algorithm with a time-varying factor for monophonic audio and musical signals. The pitch-shifting algorithm is based on the resampling and time-scale modification method. A new time-scale modification method has been developed which is called the Normalized Filtered Correlation Time-Scale Modification (NFC-TSM) method It uses a ring buffer for time-scaling. The best splicing point is searched in the normalized low-pass filtered signal using the Average Magnitude Difference Function (AMDF). The new method results in low-latency and high-quality pitch-shifting of musical signals.

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This paper describes a sound synthesis technique that modulates the coefficients of allpass filter chains using audio-rate frequencies. It was found that modulating a single allpass filter section produces a feedback AM–like spectrum, and that its bandwidth is extended and further processed by non-sinusoidal FM when the sections are cascaded. The cascade length parameter provides dynamic bandwidth control to prevent upper range aliasing artifacts, and the amount of spectral content within that band can be controlled using a modulation index parameter. The technique is capable of synthesizing rich and evolving timbres, including those resembling classic virtual analog waveforms. It can also be used as an audio effect with pitch-tracked input sources. Software and sound examples are available at http://www.acoustics.hut.fi/publications/papers/dafx09-cm/

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This paper presents our research efforts to synthesize complex instrumental gestures using a score-based control scheme. Our specific goal is to simulate the rasgueado technique that is popular especially in flamenco music. This technique is also used in the classical guitar repertoire. Rasgueado is especially challenging as ordinary music notation is not adequate to represent the dense stream of notes required for a convincing simulation. We will take two approaches to realize our task. First, we use the practical knowledge of how the actual performance is accomplished by the human player. A second, complementary, approach is to analyze an excerpt from real guitar playing. Our main focus here is to extract the onset times and the amplitudes of the recoded gesture. Next we combine the results from the two analysis steps using a constraintbased approach to find possible pitch and fingering sequences. Finally we translate the findings to our macro-note scheme that allows us to fill algorithmically a musical score.

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