Download Wave Field Synthesis - Generation and Reproduction of Natural Sound Environments Since the early days of stereo good spatial sound impression had been limited to a small region, the so-called sweet spot. About 15 years ago the concept of wave field synthesis (WFS) solving this problem has been invented at TU Delft, but due to its computational complexity it has not been used outside universities and research institutes. Today the progress of microelectronics makes a variety of applications of WFS possible, like themed environments, cinemas, and exhibition spaces. This paper will highlight the basics of WFS and discuss some of the solutions beyond the basics to make it work in applications.
Download Hierarchical Organization and Visualization of Drum Sample Libraries Drum samples are an important ingredient for many styles of music. Large libraries of drum sounds are readily available. However, their value is limited by the ways in which users can explore them to retrieve sounds. Available organization schemes rely on cumbersome manual classification. In this paper, we present a new approach for automatically structuring and visualizing large sample libraries through audio signal analysis. In particular, we present a hierarchical user interface for efficient exploration and retrieval based on a computational model of similarity and self-organizing maps.
Download Exponential Weighting Method for Sample-by-Sample Update of Warped AR-Model Auto-regressive (AR) modeling is a powerful tool having many ap plications in audio signal processing. The modeling procedure can be focused to low or high frequency range using frequency warp ing. Conventionally the AR-modeling procedure is accomplished with frame-by-frame processing which introduces latency. As with any frame-by-frame algorithm full frame has to be available for the algorithm before any output can be produced. This latency makes AR-modeling more or less unusable in real-time sound effects es pecially when long frame lengths are required. In this paper we introduce an exponential weighting (EW) method for sample-bysample update of the warped AR-model. This method reduces the latency down to the order of the AR-model.
Download Emulating Rough and Growl Voice in Spectral Domain This paper presents a new approach on transforming a modal voice into a rough or growl voice. The goal of such transformations is to be able to enhance voice expressiveness in singing voice productions. Both techniques work with spectral models and are based on adding sub-harmonics in frequency domain to the original input voice spectrum.
Download Sparse and Structured Decompositions of Audio Signals in Overcomplete Spaces We investigate the notion of “sparse decompositions” of audio signals in overcomplete spaces, ie when the number of basis functions is greater than the number of signal samples. We show that, with a low degree of overcompleteness (typically 2 or 3 times), it is possible to get good approximation of the signal that are sparse, provided that some “structural” information is taken into account, ie the localization of significant coefficients that appears to form clusters. This is illustrated with decompositions on a union of local cosines (MDCT) and discrete wavelets (DWT), that are shown to perform well on percussive signals, a class of signals that is difficult to sparsely represent on pure (local) Fourier bases. Finally, the obtained clusters of individuals atoms are shown to carry higher levels of information, such as a parametrization of partials or attacks, and this is potentially useful in an information retrieval context.
Download Transforming Singing Voice Expression - The Sweetness Effect We propose a real-time system which is targeted to music production in the context of vocal recordings. The aim is to transform the singer’s voice characteristics in order to achieve a sweet sounding voice. It combines three different transformations namely SubHarmonic Component Reduction (reduction of sub-harmonics, which are found in voices with vocal disorders), Vocal Tract Excitation Modification (to achieve a change in loudness) and the Intonation Modification (to achieve smoother transitions in pitch). The transformations are done in the frequency domain based on an enhanced phase-locked vocoder. The Expression Adaptive Control estimates the amount of present vocal disorder in the singer’s voice. This estimate automatically controls the amount of SubHarmonic Component reduction to assure a natural sounding transformation.
Download Audio-Based Gesture Extraction on the ESITAR Controller Using sensors to extract gestural information for control parameters of digital audio effects is common practice. There has also been research using machine learning techniques to classify specific gestures based on audio feature analysis. In this paper, we will describe our experiments in training a computer to map the appropriate audio-based features to look like sensor data, in order to potentially eliminate the need for sensors. Specifically, we will show our experiments using the ESitar, a digitally enhanced sensor based controller modeled after the traditional North Indian sitar. We utilize multivariate linear regression to map continuous audio features to continuous gestural data.
Download A Fast Mellin Transform with Applications in DAFx Many digital audio effects rely on transformations performed in the Fourier-transformed (frequency) domain. However, other transforms and domains exist and could be exploited. We propose to use the Mellin transform for a class of sound transformations. We present a fast implementation of the Mellin transform (more precisely a Fast Scale Transform), and we provide some examples on how it could be used in digital audio effects.
Download Audio Analysis, Visualization, and Transformation with the Matching Pursuit Algorithm The matching pursuit (or MP) algorithm decomposes audio data into a collection of thousands of constituent sound particles or gaborets. These particles correspond to the “quantum” or granular model of sound posited by Dennis Gabor. This robust and highresolution analysis technique creates new possibilities for sound visualization and transformation. This paper presents an account of a first round of experiments with MP-based visualization and transformation techniques.
Download The Feathered Clarinet Reed In this research, a method previously In this research, a method previouslyapplied appliedtotoimprove improve a digital simulation of the avian syrinx is adapted to the geometry of the clarinet reed. The clarinet model is studied with particular attention to the case when the reed beats again the lay of the mouthpiece, closing off air flow to the bore once each period. In place of the standard reed table which gives steady-state volume flow as a function of constant pressure difference across the reed, a more realistic dynamic volume flow model is proposed. The differential equation governing volume flow dynamics is seen to have a singularity at the point of reed closure, where both the volume flow and reed channel area become zero. The feathered clarinet reed refers to the method, first used in the syrinx, to smooth or feather the volume flow cutoff in a closing valve. The feathered valve eliminates the singularity and reduces artifacts in the simulated clarinet output.