Download Audio analysis in PWGLSynth In this paper, we present an incremental improvement of a known fundamental frequency estimation algorithm for monophonic signals. This is viewed as a case study of using our signal graph based synthesis language, PWGLSynth, for audio analysis. The roles of audio and control signals are discussed in both analysis and synthesis contexts. The suitability of the PWGLSynth system for this field of applications is examined and some problems and future work is identified.
Download On the control of the phase of resonant filters with applications to percussive sound modeling Source-filter models are widely used in numerous audio processing fields, from speech processing to percussive/contact sound synthesis. The design of filters for these models—be it from scratch or from spectral analysis—usually involves tuning frequency and damping parameters and/or providing an all-pole model of the resonant part of the filter. In this context, and for the modelling of percussive (non-sustained) sounds, a source signal can be estimated from a filtered sound through a time-domain deconvolution process. The result can be plagued with artifacts when resonances exhibit very low bandwidth and lie very close in frequency. We propose in this paper a method that noticeably reduces the artifacts of the deconvolution process through an inter-resonance phase synchronization. Results show that the proposed method is able to design filters inducing fewer artifacts at the expense of a higher dynamic range.
Download Real-time detection and visualization of clarinet bad sounds This paper describes an approach on real-time performance 3D visualization in the context of music education. A tool is described that produces sound visualizations during a student performance that are intuitively linked to common mistakes frequently observed in the performances of novice to intermediate students. The paper discusses the case of clarinet students. Nevertheless, the approach is also well suited for a wide range of wind or other instruments where similar mistakes are often encountered.
Download Instrument reusability scheme in PWGLSynth This paper presents our recent developments that aim to make the instrument definition process of our visual synthesis environment more accessible to a broader audience. There are several novel aspects that aim to overcome some of the classical limitations found in sound synthesis systems. After an introductory section we discuss two advanced examples where scores containing several model-based instrument parts can be realized without having to edit the original instrument definitions. In the first one, we can duplicate instrumental parts of a single instrument definition. In the latter example, we can mix in a single score several instrument models with the help of a mixer patch that is automatically created by system.
Download Audio synthesis by bitwise logical modulation The synthesis of rich audio spectra requires usually complex source waveforms, a large number of simple source components, or increased algorithmic complexity. This paper describes an implementation, which shows that simple elementary bitwise logical operations (OR, AND, XOR) possess power to produce such spectra. Applying these operations to two sinusoidal audio oscillators produced wide variety of new harmonically related sonic material. The synthesis method is efficient to implement and easily controllable, but it is not generally band-limited.
Download Score level timbre transformations of violin sounds The ability of a sound synthesizer to provide realistic sounds depends to a great extent on the availability of expressive controls. One of the most important expressive features a user of the synthesizer would desire to have control of, is timbre. Timbre is a complex concept related to many musical indications in a score such as dynamics, accents, hand position, string played, or even indications referring timbre itself. Musical indications are in turn related to low level performance controls such as bow velocity or bow force. With the help of a data acquisition system able to record sound synchronized to performance controls and aligned to the performed score and by means of statistical analysis, we are able to model the interrelations among sound (timbre), controls and musical score indications. In this paper we present a procedure for score-controlled timbre transformations of violin sounds within a sample based synthesizer. Given a sound sample and its trajectory of performance controls: 1) a transformation of the controls trajectory is carried out according to the score indications, 2) a new timbre corresponding to the transformed trajectory is predicted by means of a timbre model that relates timbre with performance controls and 3) the timbre of the original sound is transformed by applying a timevarying filter calculated frame by frame as the difference of the original and predicted envelopes.
Download Improved control for selective minimization of masking using inter-channel dependancy effects A digital audio effect for real time mixing applications, which dynamically adapts to the multi-channel input, has been implemented. The resulting audio mix is the direct result of the analysis of the content of each individual channel with respect to the other channels. The implementation permits the enhancement of a source with respect to the rest of the mixture by selectivity unmasking its spectral content from spectrally related channels. A masking measurement has also been implemented in order to measure the efficiency of the algorithm.
Download Coefficient-modulated first-order allpass filter as distortion effect A novel approach to implement the distortion effect is introduced. The proposed approach is based on time-varying phase distortion of the input signal, and it is implemented using a coefficient modulated first-order allpass filter. This new technique provides control over the distorted band with a proper choice of the modulating signal. By choosing a modulating signal that applies the phase distortion only for low frequencies, the aliasing often generated by conventional distortion effects, which modify the signal amplitude, can be greatly reduced. Modulation signals that produce distortion effects applicable for electric guitar playing are also discussed. Sound examples on the use of the filter can be found at http://www.acoustics.hut.fi/~jpekonen/ Papers/dafx08/.
Download Nonlinear modeling of a guitar loudspeaker cabinet Distortion is a desirable effect for sound coloration in electric guitar amplifiers and effect processors. At high sound levels, particularly at low frequencies, the loudspeakers used in classic style cabinets are also a source of distortion. This paper presents a case study of measurements and digital modeling of a typical guitar loudspeaker as a real-time audio effect. It demonstrates the complexity of the driver behavior, which cannot be efficiently modeled in true physical detail. A model with linear transfer functions and static nonlinearity characteristics to approximate the measured behavior is derived based upon physical arguments. An efficient method to simulate radiation directivity is also proposed.