Download j-DAFx - Digital Audio Effects in Java
This paper describes an attempt to provide an online learning platform for digital audio effects. After a comprehensive study of different technologies presenting multimedia content dynamically reacting to user input, we decided to use Java Applets. Further investigations regard the implementation issues - especially the processing and visualization of audio data - and present a general framework used in our department. Recent and future digital effects implemented in this framework can be found on our web site.
Download A library for realtime 3D binaural sound reproduction in pure data(PD)
This paper presents a library for programming 3D binaural sound reproduction systems using Pure Data (pd), an open source computer music programming language. The theory that forms the basis of the proposed library is an improved virtual Ambisonics approach. Using this approach provides computationally efficient implementation of multiple moving sound sources, room simulation, head tracking and time varying listener positions in virtual space. Furthermore, simple GUI objects for controlling parameters are implemented to provide easy to use environment.
Download Everyday sounds with the digital Intonarumori
A digital simulation of the Intonarumori, musical instruments invented by the Italian Futurist composer and painter Luigi Russolo is proposed. By building physical models of different members of the Intonarumori family, a preservation of an important contribution to the musical heritage of the beginning of the 20th century is achieved.
Download Sound quality of an Augmented Reality Audio headset
In augmented reality audio applications the user is exposed to a pseudo-acoustic reproduction of the real acoustic environment. This means that the surrounding sounds are heard through a specific augmented reality audio (ARA) headset . Ideally the pseudoacoustic environment should be an exact copy of the real acoustic environment. The acceptability and usefulness of such a headset depends strongly on the overall sound quality of the headset. Especially if the headset is to be worn for longer periods of time in everyday life situations, the sound quality of the system must be sufficient. In this paper an introduction to the aspects affecting the sound quality of an ARA-headset is addressed. In addition, results of a listening test for the overall sound quality of a well equalized headset are presented.
Download Fast implementation for non-linear time-scaling of stereo signals
In this paper we present an improved implementation of Duxbury’s adaptive phase-vocoder approach for audio time-stretching using non-linear time-scaling and temporal masked phase locking at transients . We show that the previous algorithm has some limitations, notably its slow implementation and its incapacity to deal with stereo signals. We propose solutions to this problems including: an improved transient detection, a much faster implementation using the IFFT for re-synthesis and a method for stretching stereo signals without artifacts. Finally, we provide some graphical results and quantitative measures to illustrate our improvements.
Download Morphing techniques for enhanced scat singing
In jazz, scat singing is a phonetic improvisation that imitates instrumental sounds. In this paper, we propose a system that aims to transform singing voice into real instrument sounds, extending the possibilities for scat singers. Analysis algorithms in the spectral domain extract voice parameters, which drive the resulting instrument sound. A small database contains real instrument samples that have been spectrally analyzed offline. Two different prototypes are introduced, producing sounds of a trumpet and a bass guitar respectively.
Download Separation of overlapping impulsive sounds by bandwise noise interpolation
The task of extracting harmonic content of multiple pitched sources from a mono audio mix has been investigated on several occasions [1, 2, 3, 4]. However, most pitched notes contain an inharmonic component, which is an important perceptual attribute of the sound. This content is usually not dealt with during separation. It would also be interesting in its own right to develop separation techniques for extracting percussive sounds for polyphonic mixes. This paper describes an attempt at separating overlapping impulsive content of multiple sources from a mono mix. The method uses an interpolation within individual frequency bands of the decaying noise envelope of each source across overlapping sections with other sources. Three analysis methods determining the distribution of these bands were tested: the DFT followed by processing in Bark bands, the discrete wavelet transform (DWT), and the dyadic wavelet packet transform (DWPT).
Download Playing cylinders of mechanical organs with an optical reader
This study presents an experimental setup designed to read, by means of optical techniques, the music inscribed on automatic organ cylinders. We describe the acquisition principle based on images taken by a CCD linear camera, and the various digital signal processing techniques employed to retrieve the music from the images. Preliminary results show that this original method is a relevant choice, since on our test cylinder about 90 % of the notes are correctly identified, with only 14 % of false alarms. However, for realistic estimates of the actual music, some improvements are still necessary, both in the experimental setup and in the way individual note positions are converted into music.
Download A robust algorithm for partial tracking of music signals
In this paper we propose a novel approach for tracking of partials in music signals based on a robust Kalman filter. Our tracker is based on a regularized least-squares approach that is designed to minimize the worst-possible regularized residual norm over the class of admissible uncertainties at each iteration. We introduce a set of state-space models for our signals based on the evolution of frequency and amplitude in different classes of musical instruments. These prior models are used to estimate future values of partial tracks in successive time frames of our spectral data. Here, the parameters of evolution models are treated as bounded uncertainties and our tracker can robustly track partials in all frequency regions. Unlike the conventional Kalman tracker, performance of this tracker is not influenced by the magnified track variations in higher frequencies. This tracker promises an improved performance over conventional Kalman tracker while preserving its good properties and superiority over existing methodologies.