CONTENTS
April 2007
| Vol 35 No 1 |
CONTENTS |
April 2007 |
Acoustics of Six Historic Cinemas in New South Wales, Australia
Kamani Koralage and Densil Cabrera
Improving the Upright Piano
Martin Keane
Clarinet Acoustics: Introducing a Compendium of Impedance and Sound Spectra
Paul Dickens, Ryan France, John Smith and Joe Wolfe
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Vol. 35, No. 1 pp 5 - 8 (2007)
ABSTRACT: Historic cinemas, some of which were built before sound film, are often heritage listed, placing significant limitations on architectural modifications. Such cinemas may face challenges in complying with modern audio and acoustical standards and recommendations. This paper outlines the acoustical conditions in selected historic cinemas of New South Wales, Australia. Background noise, reverberation time, speech intelligibility and impulse response measurements were made, and the room and sound system configurations were noted. Deviations from modern acoustical standards were observed. Room size, interior finishes, and the presence of galleries sometimes pose challenges for acoustical performance.
Vol. 35, No. 1 pp 11 - 15 (2007)
ABSTRACT: This paper reports a study of piano vibrations, undertaken to find whether improvements may be achieved by altering the piano case materials. Modal analysis and sound level measurements showed that, because of the manner in which sound is radiated by the piano, the tone does not change significantly when typical materials are used in the case. A method was developed for analysing the spectra of recorded notes; it showed differences in vibrations between upright and grand pianos. A finite element model of a piano suggested that changing one component (the keybed) of the upright would reduc the key vibration level and make the upright feel more like a grand. These changes were made to one of a pair of pianos, which were subjectively compared by a group of pianists; the results showed that the upright piano had been improved.
Vol. 35, No. 1 pp 17 - 23 (2007)
ABSTRACT: This paper introduces a web-based database that contains details of the acoustics of the clarinet for all standard fingerings and some others. It includes the acoustic impedance spectra measured at the mouthpiece and sound spectra recorded for each note. The data may be used to explain a number of the playing characteristics of the instrument, both in general and in detail. In this paper we give an overview, and highlight some interesting phenomena. The clarinet has, very approximately, a cylindrical bore, which is acoustically closed at one end and open at the other. Because it is so often used as an example of closed-open pipe, we show several phenomena that can be clarified by comparing measurements on a clarinet with those on a cylinder of equivalent acoustic length. We also compare these data with analogous data for the flute, an example of an open-open pipe.