Download Sound Modeling from the Analysis of Real Sounds
This work addresses sound modeling using a combination of physical and signal models with a particular emphasis on the flute sound. For that purpose, analysis methods adapted to the nonstationary nature of sounds are developed. Further on parameters characterizing the sound from aperceptive and a physical point of view are extracted. The synthesis process is then designed to reproduce a perceptive effect and to simulate the physical behavior of the sound generating system. The correspondence between analysis and synthesis parameters is crucial and can be achieved using both mathematical and perceptive criteria. Real-time control of such models makes it possible to use specially designed interfaces mirroring already existing sound generators like traditional musical instruments.
Download Low bit-rate audio coding with hybrid representations
We present a general audio coder based on a structural decomposition : the signal is expanded into three features : its harmonic part, the transients and the remaining part (referred as the noise). The rst two of these layers can be very eciently encoded in a wellchosen basis. The noise is by construction modelized as a gaussian (colored) random noise. Furthermore, this decomposition allows a good time-frequency psycoacoustic modeling, as it dircetly provides us with the tonal and nontonal part of the signal.
Download Wavelet based Method for audio-video synchronization in broadcasting applications
The difference between standards used for films and for video generates problems when a conversion from one format to another is required : Since all the images are displayed, the change of frame rate induces a pitch change on the sound. To avoid this problem, the whole soundtrack has to be processed during the duplication. In this paper, we address the corresponding sound transformation problem, namely the dilation of the sound spectrum without changing its duration. For broadcasting applications, the ratio of transposition is within the range 24/25-25/24. The wide variety of sounds (music, speech, noise…) used in movies led us to first construct a database of representative sounds containing both transient, noisy and quasiperiodic sounds. This database has been used to compare the performances of different approaches. The reviewing of the most well known methods clearly shows significant disparities between them according to the class of the signal. This led us to reconsider the problem and to propose methods based on wavelet transforms.
Download Digital Synthesis Models of Clarinet-Like Instruments Including Nonlinear Losses in the Resonator
This paper presents a real-time algorithm for the synthesis of reed instruments, taking into account nonlinear losses at the first open tonehole. The physical model on which the synthesis model relies on is based on the experimental works of Dalmont et al. who have shown that for high pressure levels within the bore, an air jet obeying the Bernoulli flow model, hence acting as a nonlinear resistance, is created at the open end of the bore. We study the effect of these additional losses on the response of the bore to an acoustic flow impulse at different levels and on the self oscillations. We show that at low frequencies, these nonlinear losses are of the same order of magnitude than the viscothermal linear losses and modifie the functioning of the whole instrument. For real-time synthesis purposes, a simplified algorithm is proposed and compared to the more accurate model.