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The Influence of the Measurement Chain on the Impulse Response of a Reverberation Room and Its Application Listening Tests

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Małecki P., Zastawnik M., Wiciak J., Kamisiński T.

Acta Physica Polonica A

2011

vol. 119

issue 6A

1027-1030

There are many objective parameters of the room impulse response which we can calculate that describe its acoustic field. The room impulse response can also be used to provide listening tests using the convolution technique. The aim of this work is to consider the influence of the impulse response measurement chain on objective numerical parameters and on the subjective perception of listeners. This article shows the impulse response measurement results obtained in the reverberation room using not only commonly known measurement chain elements but other elements, too. Standard components such as an omni-directional source and measurement microphone, as well as a consumer active loudspeaker and various audio recording stereo microphone pairs were used. The results are compared taking into consideration calculated numerical parameters and the application of calculated impulse responses to subjective listening tests. To determine the applicability of impulse responses to psychoacoustic listening tests, a preliminary listening test using headphones was carried out on a selected group of listeners. The audio test material consisted of samples of choral music and speech recorded in an anechoic room and convolved with previously analyzed impulse responses. This article shows how big the differences of subjective listener feelings are for different acoustic transducers.

Comparison of Pressure and Intensity Methods in Evaluating the Directional Diffusion Coefficient

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Pilch A., Kamisiński T., Zastawnik M.

Acta Physica Polonica A

2013

vol. 123

issue 6

1054-1058

The directional diffusion coefficient characterizes directional uniformity of acoustic energy reflected from a structure. The goal of the paper is to check whether different measurement methods of that coefficient give comparable results and can be used for different diffusing structures. ISO 17497-2:2012 recommends two basic measurement methods for this parameter, both based on sound pressure analysis. In the first method, one microphone and a measurement manipulator is used (the space method), while in the second one, 19 microphones placed on the sound-reflecting plane are required (the boundary method). In the standard it is assumed (as usually in the room acoustics), that the acoustic energy is proportional to the square of sound pressure, what is true only for the plane wave. Correctness of this assumption was checked by the modified space method where the sound intensity probe was installed instead of microphone. The test revealed that pressure methods gave comparable results for both low- and high-diffusion structures, with the boundary method giving moderately higher values for low-diffusion structures and slightly higher for high-diffusion structures. The results obtained in the intensity method were comparable with the pressure method except for the 2000 Hz frequency range.

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2 Acta Physica Polonica A

1 2013

1 2011

2 Kamisiński T.

2 Zastawnik M.

1 Małecki P.

1 Pilch A.

1 Wiciak J.

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The Influence of the Measurement Chain on the Impulse Response of a Reverberation Room and Its Application Listening Tests

Comparison of Pressure and Intensity Methods in Evaluating the Directional Diffusion Coefficient