De Cesaris, Simona
(2014)

*A new method for the estimation of the reverberation time from measured room impulse responses with application to Italian opera houses*, [Dissertation thesis], Alma Mater Studiorum Università di Bologna.
Dottorato di ricerca in

Ingegneria energetica, nucleare e del controllo ambientale, 26 Ciclo. DOI 10.6092/unibo/amsdottorato/6410.

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## Abstract

The Schroeder's backward integration method is the most used method to extract the decay curve of an acoustic impulse response and to calculate the reverberation time from this curve. In the literature the limits and the possible improvements of this method are widely discussed.
In this work a new method is proposed for the evaluation of the energy decay curve.
The new method has been implemented in a Matlab toolbox. Its performance has been tested versus the most accredited literature method.
The values of EDT and reverberation time extracted from the energy decay curves calculated with both methods have been compared in terms of the values themselves and in terms of their statistical representativeness.
The main case study consists of nine Italian historical theatres in which acoustical measurements were performed.
The comparison of the two extraction methods has also been applied to a critical case, i.e. the structural impulse responses of some building elements.
The comparison underlines that both methods return a comparable value of the T30. Decreasing the range of evaluation, they reveal increasing differences; in particular, the main differences are in the first part of the decay, where the EDT is evaluated.
This is a consequence of the fact that the new method returns a “locally" defined energy decay curve, whereas the Schroeder's method accumulates energy from the tail to the beginning of the impulse response.
Another characteristic of the new method for the energy decay extraction curve is its independence on the background noise estimation.
Finally, a statistical analysis is performed on the T30 and EDT values calculated from the impulse responses measurements in the Italian historical theatres.
The aim of this evaluation is to know whether a subset of measurements could be considered representative for a complete characterization of these opera houses.

Abstract

The Schroeder's backward integration method is the most used method to extract the decay curve of an acoustic impulse response and to calculate the reverberation time from this curve. In the literature the limits and the possible improvements of this method are widely discussed.
In this work a new method is proposed for the evaluation of the energy decay curve.
The new method has been implemented in a Matlab toolbox. Its performance has been tested versus the most accredited literature method.
The values of EDT and reverberation time extracted from the energy decay curves calculated with both methods have been compared in terms of the values themselves and in terms of their statistical representativeness.
The main case study consists of nine Italian historical theatres in which acoustical measurements were performed.
The comparison of the two extraction methods has also been applied to a critical case, i.e. the structural impulse responses of some building elements.
The comparison underlines that both methods return a comparable value of the T30. Decreasing the range of evaluation, they reveal increasing differences; in particular, the main differences are in the first part of the decay, where the EDT is evaluated.
This is a consequence of the fact that the new method returns a “locally" defined energy decay curve, whereas the Schroeder's method accumulates energy from the tail to the beginning of the impulse response.
Another characteristic of the new method for the energy decay extraction curve is its independence on the background noise estimation.
Finally, a statistical analysis is performed on the T30 and EDT values calculated from the impulse responses measurements in the Italian historical theatres.
The aim of this evaluation is to know whether a subset of measurements could be considered representative for a complete characterization of these opera houses.

Tipologia del documento

Tesi di dottorato

Autore

De Cesaris, Simona

Supervisore

Dottorato di ricerca

Scuola di dottorato

Ingegneria industriale

Ciclo

26

Coordinatore

Settore disciplinare

Settore concorsuale

Parole chiave

Acoustics
Reverberation time
EDT
Energy decay curve
Italian historical theatres
Normality tests

URN:NBN

DOI

10.6092/unibo/amsdottorato/6410

Data di discussione

7 Maggio 2014

URI

## Altri metadati

Tipologia del documento

Tesi di dottorato

Autore

De Cesaris, Simona

Supervisore

Dottorato di ricerca

Scuola di dottorato

Ingegneria industriale

Ciclo

26

Coordinatore

Settore disciplinare

Settore concorsuale

Parole chiave

Acoustics
Reverberation time
EDT
Energy decay curve
Italian historical theatres
Normality tests

URN:NBN

DOI

10.6092/unibo/amsdottorato/6410

Data di discussione

7 Maggio 2014

URI

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