Analysis and resynthesis

The resynthesis by Fourier analysis reversion method (sometimes referred to as overlap-add resynthesis) takes the information from each frame of the STFT analysis and recreates an approximation of the original sound window by window. This process works well for those 

This method employs STFT analysis data to control an additive synthesiser. In this case, the analysis stage includes an algorithm that converts the STFT data into amplitude and frequency trajectories - or envelopes - that span across the STFT frames. This is generally referred to as the peak-tracking algorithm and can be implemented in a number of ways. 

The Phase Vocoder system implemented by the composer Trevor Wishart and his collaborators at Composer s Desktop Project (CDP) in England is a classic example of additive res)mthesis. In order to operate the Phase Vocoder the musician first needs to define a number of parameters, including the envelope for the window, the size of the window and the overlap factor. 

From the various types of envelopes for windowing available. Phase Vocoder normally employs either the Hamming function or the Kaiser function. Both functions have a bell-like shape. One may provide better analysis results than the other, depending upon the nature of the sound analysed and the kind of result expected. 

The real power of the CDP s Phase Vocoder package is the great number of tools available for spectral manipulation techniques (Wishart, 1994). There are currently over 60 tools in the package for tasks such as  

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The second step in the sequence eludes adequate description but is important. It is an understatement to describe it as a review, analysis and resynthesis of accepted knowledge about a particular study system and about its relation to its environment. Yet, that is all that can be said to characterize this second step besides acknowledging a central role for intangibles such as genius, intuition, serendipity, insights, etc. 

On an early attempt, see Homberg s and Geoffrey s analysis and resynthesis of sulfur (Klein [1994a] 25f.). 

CDPVOC is the actual program that performs the task of analysis and resynthesis the remaining are programs for spectral manipulations. Note that the spectral manipulation programs do not process a sound directly but the information generated by the analysis... 

The caveat of the PSOLA analysis and resynthesis method is that it only works satisfactorily on sounds containing regular cycles displaying a single energy point, referred to as the local maxima the human voice fulfils this requirement, but not all sounds do. The good news is that PSOLA is fast, as it deals directly with the sound samples in the time-domain. 

When designing synthesis instruments, we should give preference to those techniques that best fit the way we understand the sound phenomena we want to work with. For example, whilst those composers interested in timbral manipulation will be better off working with analysis and resynthesis techniques (Chapter 3), those working with scientific metaphors (e.g. dynamic systems, cellular automata, etc.) would certainly prefer to use granular or statistical synthesis methods (Chapter 5). 

Figure 8.18 SMS is a powerful analysis and resynthesis program for spectral modelling synthesis...

For solution-phase libraries that are composed of mixtures of compounds, the difficulty of analysis escalates with increasing numbers of compounds. Typically, large mixtures of compounds are not analyzed before screening, whereas small ones may be analyzed for reaction completeness using mass spectrometry, HPLC, NMR, or combinations thereof. The identification and analysis of active compounds from these mixtures is painstakingly tedious, and often complete characterization is possible only after deconvolution procedures and resynthesis of the active compound. For solid-phase libraries, the methods currendy developed are discussed below. 

Arfib, 1991] Atfib, D. (1991). Analysis, transformation, and resynthesis of musical sounds with the help of a time-frequency representation. In de Poli, G., Piccialli, A., and Roads, C., editors, Representation of musical signals, pages 87-118. M.I.T Press, Cambridge. 

Spectral Analysis. - A new method of analysis of ATP utilisation and resynthesis has been developed which simulates cellular ATP flux, mitochondrial oxidative phosphorylation and creatine kinase kinetics. The model was used to examine previously published P NMR data of changes in PCr and Pi in resting muscle, muscle exercising during ischaemia and muscle in aerobic recovery. The model allowed estimation of the maximal velocity of oxidative... 

The above technique bears some similarities to the TD-PSOLA technique in that it uses a pitch-synchronous analysis to isolate individual pitch periods, after which modification and resynthesis are performed. In fact, in a technique called linear-prediction pitch-synchronous overlap and add or LP-PSOLA, we can use PSOLA more or less directly on the residual rather than on the waveform. As above, epoch detection is used to find the epochs. The residual is then separated into a number of symmetrical frames centred on... 

The DCL was created under standard disulfide exchange conditions at pH 7.5. After equilibration for 48 hours, each of the expected 15 disulfide products could be observed in the library using LC-MS analysis (Fig. 2.11). The library was then equilibrated in the presence of CaM, followed by a centrifugation filtration step to separate protein/bound components from free components in solution. Analysis of the filtrate was complicated by the filtration membrane affecting the composition of the library. The bound components, however, provided meaningful results. Denaturation and filtration afforded a mixture of all peptides that had bound to CaM in the course of the DCL. HPLC analysis indicated significant amplification of dimer cc (80%) and a small amplification of dimer ec (10%). Resynthesis of these two components and binding assay established values of 10 and... 

The multiperiod synthesis-analysis-resynthesis algorithm is actually decomposed into two stages (Floudas and Grossmann, 1987b) ... 

In order to make the multiperiod synthesis-analysis-resynthesis algorithm more flexible (and to extend it later to revamp synthesis), investigate how to constrain stream splitting. 

Extend the multiperiod synthesis-analysis-resynthesis algorithm to handle temperature-dependent heat capacities and phase change and uncertain heat transfer coefficients. 

McMillen, 1994] McMillen, K. (1994). A Technology Dossier on Fourier Analysis Resynthesis. Oberheim Digital and G-WIZ Labs, Berkeley, CA. 

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