Download Realization of a Diffuse Sound Field with a PC-Based Sound Card Solution For the quality assessment of headphones, especially the loudness measuring of headphones, a diffuse sound field is required. At this time a hardware based noise generator, one-third octave filters built up in analog mode as well as boosters are used. In this work a flexible PC-based solution with the aid of a sound card is presented. Therefore ten independent noise generators, generating Gaussian distributed white noise, are needed. The implementation using the ’Dynamic Creation of Pseudorandom Number Genrators’ for ’Mersenne Twister’ is described. A probability transformation to convert equal distributed numbers into Gaussian distributed ones is derived in detail. Furthermore one-third octave filters are designed and implemented according to the ANSI standard. The access to the sound card is provided using the Wave-API library under Microsoft Windows. This work was carried out at Sennheiser electronic GmbH in Wennebostel (Germany) in the development department for cord based headphones.
Download A new Scheme for Real-Time Loop Music Production Based on Granular Similarity and Probability Control In this paper, a new concept of real-time loop music production is introduced, along with its implementation in Pd. This scheme tends to improvise loop music based on very limited pattern (loop sample) materials. Four loops, each divided into 32 grains, work at the same time. Analysis of the spectral and energy similarities between every two grains are conducted, and the transition probability matrices generated by the analysis phase are consulted for each decision of grain choice during remixing. A joystick-style controller is designed to control the probability distribution, which changes the music characteristics in real-time. While maintaining some characteristics of each loop pattern, the music generated by the program reveals a large space of variations and controllable improvisations. Real-time analysis is considered, that later will enable switching new patterns into the 4pattern group during a performance. This scheme is a potential new method for live computer DJ mixing in the loop pattern level. Sound examples, including four drum loops and the improvisations on them, can be found at http://crca.ucsd.edu/˜pxiang/granuloop.htm
Download Real-Time Partial Tracking in an Augmented Additive Synthesis System This paper describes an approach to real time partial tracking in an analysis\transformation\resynthesis system using a combination of linear and bi-linear time-frequency techniques. Tests of the system have been made using both natural and synthetic sounds. Results are presented and areas for further research and development are discussed.
Download Efficient Parametric Modeling for Audio Transients In this work, we present an evolution of the DDS (Damped & Delayed Sinusoidal) model introduced within the framework of the general signal modeling. This model is named Partial Damped & Delayed Sinusoidal (PDDS) model and takes into account a single time delay parameter for a set of (un)damped sinusoids. This modification is more consistent with the transient audio modeling problem. Then, we develop model parameter high-resolution estimation algorithms. Simulations on a typical transient audio signals show the validity of this approach.
Download Adapting the Overlap-Add Method to the Synthesis of Noise Spectral synthesis techniques often use the OverLap-Add method. But in the case of noise synthesis, both experiments and theory show that this method introduces intensity fluctuations which imply audible artifacts. We propose here new methods to avoid these variations. The first one consists in multiplying the resulting signal by another weighting window to compensate dynamic fluctuations. The second one defines a new OLA weighting window. The third one concerns only noises synthesized with sinusoidal components and uses time-shifting to cancel artifacts.
Download Audio Signal Extrapolation - Theory and Applications A method for extrapolating discrete audio signals is described. The theory of extrapolation is studied and some applications are presented and demonstrated. The extrapolation method is fast and capable of extrapolating several thousand samples of CD-quality audio signals. The extrapolation is applied in practice to enhance the spectral resolution in short-time fast Fourier transform based methods. It is also applied to eliminate impulsive noise bursts and to recover missing signal sections.
Download Modeling Interactions between Rubbed Dry Surfaces Using an Elasto-Plastic Friction Model A physically based model of the frictional interaction between dry surfaces is presented. The paper reviews a number of static and dynamic friction models, and discusses numerical techniques for the accurate and efficient numerical implementation of a dynamic elasto-plastic model. An application to the bowed string is provided, and the resulting simulations are compared to recent results from the literature.
Download Modeling Bowl Resonators Using Circular Waveguide Networks We propose efficient implementations of a glass harmonica and a Tibetan bowl using circular digital waveguide networks. Circular networks provide a physically meaningful representation of bowl resonators. Just like the real instruments, both models can be either struck or rubbed using a hard mallet, a violin bow, or a wet finger.
Download Real-Time Spatial Processing and Transformations of a Singing Bowl We propose different real-time spatial-modal manipulations of a physical model of a singing bowl. The high number of degrees of freedom in the model, combined with spatial processing algorithms, provides the possibility of obtaining rich and expressive transformations.
Download Inharmonic Sound Spectral Modeling by Means of Fractal Additive Synthesis In previous editions of the DAFX [1, 2] we presented a method for the analysis and the resynthesis of voiced sounds, i.e., of sounds with well defined pitch and harmonic-peak spectra. In a following paper [3] we called the method Fractal Additive Synthesis (FAS). The main point of the FAS is to provide two different models for representing the deterministic and the stochastic components of voiced-sounds, respectively. This allows one to represent and reproduce voiced-sounds without loosing the noisy components and stochastic elements present in real-life sounds. These components are important in order to perceive a synthetic sound as a natural one. The topic of this paper is the extension of the technique to inharmonic sounds. We can apply the method to sounds produced by percussion instruments as gongs, tympani or tubular bells, as well as to sounds with expanded quasi-harmonic spectrum as piano sounds.