The modeling of wave propagation in ah orn is still problematic as the limit of plane wave approximation is known butn om ethod is provent og ivea ccurate results. This paper proposes to evaluate the error induced by both ap lane wave model and as pherical model. These models use aT ransmission-Matrix Method based on either plane or quasi-spherical propagation and loaded with twod i ff erent radiation impedances. This study is done on twomusical instruments horns, one from atrumpet and the other from atrombone, whose geometry is known to within at enth of millimetre. The respective influence of both propagation and radiation is observed by comparing the input impedance measured on each of the twohorns with the impedance calculated with both models. Differences between models and measurements are quantified and an extension to awhole trombone is also done. The spherical model approximates the behaviour of the horn with an improvedaccuracyand differences between the model and the measurement do not rise above 25 cents. PACS no. 43.20.Mv,43.75Fg 158 ©S.Hirzel Verlag · EAA Eveno et al.:P ropagation and radiation in ahorn ACTA ACUSTICA UNITED WITH ACUSTICA Vol. 98 (2012)

The aim of this work is to study experimentally the relationship between the resonance frequencies of the trumpet, extracted from its input impedance, and the playing frequencies of notes, as played by musicians. Three different trumpets have been used for the experiment, obtained by changing only the leadpipe of the same instrument. After ameasurement of the input impedance of these trumpets, four musicians were asked to play the first five regimes of the instrument, for four different fingerings. This wasd one for three dynamic levels and repeated three times. Statistical methods were implemented to assess the variability in the playing frequencies, and to study quantitatively their relationships with the bore resonance frequencies. Alimited influence of the musician on the instrument overall intonation is observed, as well as aweak influence of the dynamic levels on the pitch of the notes. The results showthat for most of the regimes, variations of the resonance frequencylead to same order variations of the playing frequencyo ft he corresponding note. We noticed also that the sum function, derived from the input impedance, does not give ab etter prediction of the playing frequencyt han the input impedance itself.

The Ascomycota fungus Microcyclus ulei is a major threat for natural rubber production. The ascospores play a major role in the survival and dissemination of the fungus. The present study indicates that the ascospores are present on the leaves shortly after infection. Although their abundance is higher on leaflets 50–70 days after they reach maturity, ascospores are still found on 6 months-old leaves, ensuring the survival of the fungus during the dry season in the case of no defoliation of the rubber trees. Indeed, their viability does not depend on the age of the leaf. The pycnidiospores, whose role in the lifecycle of the fungus is not established, are also present on the leaves several months after their maturity. The ascospores are disseminated only if the leaves are wetted and exposed to an airflow. The discharge of ascospores starts a few minutes after a single wetting event but the number of ascospores discharged decreases rapidly and stops 90 min after the wetting event. However, the perithecia are rapidly able to discharge ascospores if wetted again but at a lower level. Compared to other Ascomycota, the discharge of ascospores is quick but brief. (Résumé d'auteur

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The quality of a musical instrument embraces many aspects such as tuning, ease of play, tone, etc. This study aims to validate the use of the sum function (SF) proposed by Wogram from the measurement of input impedance as a descriptor of quality. This work is part of a wider project, PAFI (Aid Platform for Instrumental Making), supported by the French National Agency of Research. To validate the choice of the SF, we created a family of trumpets made from a basic instrument for which the leadpipe will be slightly modified for each model. The SF was calculated for a range of selected frequencies from the measurement of the input impedance of these different trumpets. The next step was to ask musicians experts to play these instruments, to measure the playing frequencies, and to note their feedback about quality. These tests were supplemented by comparative tests carried out this time with the help of a robotic artificial mouth. The final step involved was to try to identify correlations between the SF and the results of various tests and propose correction factors to be made to the formula of the SF, related to the nuance or range for example.