Simona De Cesaris

Extraction of the envelope from impulse responses using pre-processed energy detection for early decay estimation

The Schroeders backward integration method and its applications have been widely studied in the literature; some papers analyze the performance of the method, some others suggest various enhancement techniques. In spite of these findings, there exist several cases where the energy decay curve extracted using the classical backward integration method and the parameters computed from it seem not always representative of the phenomenon under study. Among them, the cases where the early decay is dependent on strong, distinct reflections occurring just after the direct wave, as in most Italian opera houses. Other cases are measured impulse responses with a very low signal-to-noise ratio or missing the direct wave. In the literature, alternatives to the Schroeders method have been proposed, ranging from Hilbert transform to non-linear processing techniques. In this work a method for the extraction of the envelope based on pre-processed energy detection for early decay estimation is proposed. It is shown that it returns an envelope well matching the first part of the decay even in non-linear cases, returning detailed information on the first part of the decay. The performance of the proposed method is presented and discussed for some exemplary impulse responses measured in historical opera houses. A preliminary study on the perceptive relevance of the method is finally presented.

Recordings of Italian opera orchestra and soloists in a silent room

Anechoic recordings of symphony orchestras have been proposed in the literature and have been used in a multitude of studies concerning both innovative measurements and psychoacoustic experiments. Using the same approach, the present work shows the results of a recording campaign focused on the Italian Opera. Different motifs from Italian Operas have been played by professional musicians and soloists in the silent room of the Bologna University. The excerpts have been chosen because of their musical style characteristics and their acoustic properties (dynamics, timbre, vibrato). The chosen motifs come from scores of Donizetti, Verdi and Puccini, in order to consider various orchestrations and Opera styles.

Overall indoor quality of a non-renewed secondary-school building

This work is the result of a field study about overall comfort aspects performed in a secondary-school building in the surroundings of Bologna during the winter season. The campaign aimed at describing overall comfort aspects of the school both from an objective and a subjective point of view, thus a questionnaire was administered to pupils during ongoing lessons to compare physical measurements and subjective responses. The monitored attributes and items concerned typical indoor quality aspects: acoustical, thermal, indoor air, and visual quality. As weak points emerged from the data analysis, possible solutions are illustrated, focusing on acoustics and optimizing effectiveness and cost.

Sound energy distribution in Italian opera houses

A typical Italian opera house is a complex system of coupled volumes: fly tower, orchestra pit, cavea (the volume where the stalls are), boxes, loggione (gallery). The way of propagation of the sound energy between one volume and the others is still a subject of research. The present work gives a contribution to the discussion by applying the Barron’s revised theory to the analysis of recent measurements done in several Italian theatres. The averaged values of sound strength versus the distance from the sound source is plotted inserting in the Barron’s equation either the classical reverberation time or the early decay time and different volume values. The significance of the different choices and their agreement with the experimental values are discussed. It is concluded that the spatial distribution of sound strength depends on the sound source position.