Download Extraction of the excitation point location on a string using weighted least-square estimation of a comb filter delay This paper focuses on the extraction of the excitation point location on a guitar string by an iterative estimation of the structural parameters of the spectral envelope. We propose a general method to estimate the plucking point location, working into two stages: starting from a measure related to the autocorrelation of the signal as a first approximation, a weighted least-square estimation is used to refine a FIR comb filter delay value to better fit the measured spectral envelope. This method is based on the fact that, in a simple digital physical model of a plucked-string instrument, the resonant modes translate into an all-pole structure while the initial conditions (a triangular shape for the string and a zero-velocity at all points) result in a FIR comb filter structure.
Download Investigations with the Sonic browser on two of the perceptual auditory dimensions of sound objects: Elasticity and force The Sonic Browser is a software tool developed especially for navigating among sounds in a 2-D space, primarily through listening. It could be used for managing large collections of sounds, but now it is turning out to be useful also for conducting psychophysical experiments, aiming at investigating perceptual dimension scaling of sounds. We used it for analyzing the relationship between the physical parameters involved in the sound synthesis and for studying the quality of the sounds generated by the SOb models. Some experiments in this direction have been already reported [1, 2], examining real and model generated sounds of impacts and bounces of objects made with different materials. In this paper, we introduce our further investigations, by analyzing perceptually the impacts and bounces sounds from a different perspective, focusing on other two perceptual dimensions, i.e elasticity of the event and the force applied to the dropped object. We will describe the new experiment we conducted and we will report the collected data, by analyzing the resulting perceptual evaluation spaces.
Download A hybrid approach to timbral consistency in a virtual instrument The aim of this work is to make an instrument that is timbrally consistent over pitch and loudness. This particular work is not attempting to reproduce an existing instrument’s timbre, but to produce a timbrally dynamic virtual instrument that can be designed by the user. In this paper there is a brief introduction to timbre and synthesis methods, followed by a proposal on how to make timbrally consistent virtual instruments out of given timbres.
Download Introducing Audio D-TOUCH: A tangible user interface for music composition and performance "Audio d-touch" uses a consumer-grade web camera and customizable block objects to provide an interactive tangible interface for a variety of time based musical tasks such as sequencing, drum editing and collaborative composition. Three instruments are presented here. Future applications of the interface are also considered.
Download FFT analysis as a creative tool in live performance This paper describes the use of real time spectral analysis to enhance the creative opportunities in improvised live electronics/instrumental performance. FFT analysis allows musicians to observe in performance a visual representation of the spectrum, displaying the spectral characteristics of audio resulting from performance activity and/or computer processing. These characteristics can then be explored during performance, assigning areas of special interest within the spectrum to parameters which in turn control (or at least influence) electronic processing. This creates an effective, easily manipulated but potentially highly complex performance environment, encouraging further interaction between improvising performers, and allowing subtle and complex links to emerge between the timbral features of actual music (result) and the act of performance (cause). We hope to increase awareness of the performance-specific potential of familiar analytical tools, of which FFT is one example, and their unfulfilled creative potential.
Download A simple, accurate wall loss filter for acoustic tubes This research presents a uniform approximation to the formulas of Benade and Keefe for the propagation constant of a cylindrical tube, valid for all tube radii and frequencies in the audio range. Based on this approximation, a simple expression is presented for a filter which closely matches the thermoviscous loss filter of a tube of specified length and radius at a given sampling rate. The form of this filter and the simplicity of coefficient calculation make it particularly suitable for real-time music applications where it may be desirable to have tube parameters such as length and radius vary during performance.
Download On the use of spatial cues to improve binaural source separation Motivated by the human hearing sense we devise a computational model suitable for the localization of many sources in stereo signals, and apply this to the separation of sound sources. The method employs spatial cues in order to resolve high-frequency phase ambiguities. More specifically we use relationships between the short time Fourier transforms (STFT) of the two signals in order to estimate the two most important spatial cues, namely time differences (TD) and level differences (LD) between the sensors. By using models of both free field wave propagation and head related transfer functions (HRTF), these cues are combined to form estimates of spatial parameters such as the directions of arrival (DOA). The theory is validated with the help of the experimental results presented in the paper.
Download Sound spatialization based on fast beam tracing in the dual space This paper addresses the problem of geometry-based sound reverberation for applications of virtual acoustics. In particular, we propose a novel method that allows us to significantly speed-up the construction of the beam tree in beam tracing applications, by avoiding space subdivision. This allows us to dynamically recompute the beam tree as the sound source moves. In order to speedup the construction of the beam tree, we determine what portion of which reflectors the beam “illuminates” by performing visibility checks in the “dual” of the geometric space.