Download Inverting the Clarinet
Physical-modelling based sound resynthesis is considered by estimating physical model parameters for a clarinet-like system. Having as a starting point the pressure and flow signals in the mouthpiece, a two-stage optimisation routine is employed, in order to estimate a set of physical model parameters that can be used to resynthesise the original sound. Tested on numerically generated signals, the presented inverse-modelling method can almost entirely resynthesise the input sound. For signals measured under real playing conditions, captured by three microphones embedded in the instrument bore, the pressure can be successfully reproduced, while uncertainties in the fluid dynamical behaviour reveal that further model refinement is needed to reproduce the flow in the mouthpiece.
Download Principal Component Analysis of Rasterised Audio for Cross-Synthesis
This paper describes a system for cross synthesis of rasterised time-domain audio. Rasterisation of the audio allows alignment of the macroscopic features of audio samples of instrument tones prior to principal component analysis (PCA). Specifically a novel algorithm for straightening and aligning rastogram features has been developed which is based on an interactive process incorporating the Canny detection algorithm and variable resampling. Timbral cross-synthesis is achieved by projecting a given instrument tone onto the principal components derived from a training set of sounds for a different tone. The alignment algorithm improves the efficiency of PCA for resynthesizing tones.
Download New Method for Analysis and Modeling of Nonlinear Audio Systems
In this paper a new method for analysis and modeling of nonlinear audio systems is presented. The method is based on swept-sine excitation signal and nonlinear convolution firstly presented in [1, 2]. It can be used in nonlinear processing for audio applications, to simulate analog nonlinear effects (distortion effects, limiters) in digital domain.
Download Fluently Remixing Musical Objects with Higher-Order Functions
Soon after the Echo Nest Remix API was made publicly available and open source, the primary author began aggressively enhancing the Python framework for re-editing music based on perceptually-based musical analyses. The basic principles of this API – integrating content-based metadata with the underlying signal – are described in the paper, then the authors’ enhancements are described. The libraries moved from supporting an imperative coding style to incorporating influences from functional programming and domain specific languages to allow for a much more fluent, terse coding style, allowing users to concentrate on the functions needed to find the portions of the song that were interesting, and modifying them. The paper then goes on to describe enhancements involving mixing multiple sources with one another and enabling user-created and user-modifiable effects that are controlled by direct manipulation of the objects that represent the sound. Revelations that the Remix API does not need to be as integrated as it currently is point to future directions for the API at the end of the paper.
Download Handling Inharmonic Series with Median-Adjustive Trajectories
A new method for the analysis of inharmonic instrumental tones is presented. The method exploits an equation derived from the well-know inharmonic series equation, where the inharmonicity coefficient is balanced with the frequencies and numbers of any two partials extracted from a pseudo-harmonic series. A serial search for increasingly deviating spectral peaks is aided with the integrated refinement of increasingly reliable inharmonicity coefficient and fundamental frequency estimates. This firsthand approach to the problem of evaluating inharmonic spectra brings about an unprecedented level of simplicity, efficiency and accuracy.
Download KRONOS ‐ A Vectorizing Compiler for Music DSP
This paper introduces Kronos, a vectorizing Just in Time compiler designed for musical programming systems. Its purpose is to translate abstract mathematical expressions into high performance computer code. Musical programming system design criteria are considered and a three-tier model of abstraction is presented. The low level expression Metalanguage used in Kronos is described, along with the design choices that facilitate powerful, yet transparent vectorization of the machine code.
Download Compositional Sketches in PWGLSynth
PWGLSynth has already a long history in controlling physicsbased instruments. The control system has been score-based, i.e. the user prepares a score in advance, and by interactive listening process the result can be be refined either by adjusting score information, performance rules and/or the visual instrument definition. This scheme allows detailed control on how the instrument model reacts to control information generated from the score. This paper presents a complementary approach to sound synthesis where the idea is to generate algorithmically typically relatively short musical textures. The user can improvise with various compositional ideas, adjust parameters, and listen to the results in real-time either individually or interleaved. This is achieved by utilizing a special code-box scheme that allows any textual Lisp expression to be interfaced to the visual part of the PWGL system.
Download Tools for Interactive Audio Signal Analysis based on Sliding DFT
This article describes an application the author developed in order to compare analysis and synthesis of musical audio signals through Short Time Fourier transform (STFT), Constant Q and Sliding Discrete Fourier Transform (SDFT). This software is the basis for applications of SDFT and Constant Q to other consolidated synthesis techniques. By itself, it is a stand alone instrument for calculating and quickly comparing spectrum analysis and synthesis of musical signals. No expertise is required and it can for example be easily used by music composers without in depth knowledge of DSP processing tools.
Download A VST Reverberation Effect Plugin Based on Synthetic Room Impulse Responses
In this paper we present a newly developed VST reverberation effect plugin (“HybridReverb”) based on synthetic room impulse responses (RIRs). We detail how we choose proper parameters for the synthesis of RIRs as presets for our convolution-based reverberation effect. The implemented stereo/surround plugin provides natural sounding reverberation based on physical principles. The newly developed convolution engine features signal processing with low latency and uniform processing load.
Download A spectral subtraction rule for real‐time DSP implementation of noise reduction in speech signals
Spectral subtraction is a method for restoration of the spectrum magnitude for signals observed in additive noise, through subtraction of an estimate of the average noise spectrum from the noisy signal spectrum. In this paper we show that, starting from the known minimum mean-square error (MMSE) suppression rules of Ephraim and Malah and under the same modeling assumptions, a simpler suppression filtering rule can be found. Moreover, we demonstrate its performances and compare its computational costs with respect to the reference rule of Ephraim and Malah. This result permits a real time implementation of the exposed theory with an efficient algorithm on the DSP TMS320 C6713B.