A compositional approach to analysis re-synthesis
This report summarises the work achieved in the framework of a composer in research project in the IMTR team at IRCAM. In this project we have experimented with different realtime processing techniques for the analysis, transformation, and resynthesis of particular morphological aspects of live performed voice and instrumental sounds. Based on segment-wise sound descriptions, the developed tools allow for re-orchestrating and re-organising particular morphological aspects of the live performer's sound using concatenative synthesis of pre-analysed sound materials driven by the real-time analysis. The relationship between the morphology of live performance and the synthesised sound materials is controlled by a set of compositional tools manipulating the extracted sound descriptions in real-time.
First Steps in Relaxed Real-Time Typo-Morphological Audio Analysis/Synthesis
This paper describes a real-time audio analysis/resynthesis system that we developed for a music piece for ensemble and electronics. The system combines real-time audio analysis and concatenative synthesis based on the segmentation of sound streams into constituting segments and the description of segments by an efficient set of descriptors adapted to the given musical context. The system has been implemented in Max/MSP using the FTM & Co and MuBu libraries and successfully employed in the production and performance of the piece. As more and more research in the domain of music information retrieval, we use the term of typo-morhpology to designate the description of sounds by morphologic criteria including the temporal evolution of sound features that also can provide pertinent means for the classification of sounds. Although, the article mainly insists on the technical aspects of the work, it occasionally contextualizes the different technical choices regarding particular musical aspects.
Hygroscopic Expansion of some Casting Investments
CREDIT is generally given to Taggart1 for introducing the cast gold inlay to the dental profession. Although he realized that gold shrinks when cooled from molten state to solid state of room temperature, the investment available to him did not supply sufficient compensation. In 1910, Van Horn2 published a paper dealing with a method by which he obtained the compensation by means of wax expansion. The next major research in connection with this problem was the work of Coleman3 at the National Bureau of Standards. He determined the gold shrinkage to be 1.25 per cent and presented a casting technic with compensation values of quantitative nature. The total compensation for the gold shrinkage was obtained by the combination of the setting and thermal expansion of the mold. This procedure is the general practice followed at the present time for compensation. There are some disadvantages to this method. Skinner has indicated the difficulty of obtaining smooth castings and the improper compensation for the casting shrinkage.4 It has been found by Hollenback5 and Scheu6a that castings made at a high temperature are rougher than those made at a low temperature (450° C.), depending upon the great difference in thermal expansion between plaster of Paris and silica, which causes a poor union of the fine particles. This may also result in friability and there may be some warpage due to the differential expansion. A method which provides sufficient compensation at a low mold temperature is the hygroscopic casting technic.b Wilson7 showed that certain plasters expand as much as 0.0044 inch to the inch by taking up moisture from the air. With this information at hand, Scheula, b tested some commercial investment to determine what results the addition of moisture would have. He found6b: (1) All of the casting investments that were tested expanded. (2) The thicker the mix, the greater the expansion. (3) A mix with hot water expanded more than one with cold water. (4) The time at which the mix is placed in the water is of great importance. It was found that if the mix is placed in the water early, it would not expand so much as when placed in a little later. It was also found that if the mix was placed in the water after a certain time, it could not expand to the maximal amount. (5) The temperature of the water in which the mix is placed is important, for two reasons; (a) the temperature of the water controls slightly the expansion of the investment, and (b) water at a temperature of 1000 F. slightly softens the wax pattern so that the fine margins are not marred while expansion is taking place. The mix should remain in the water at least 20 minutes to obtain the full expansion, after which time no further expansion is obtained.