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The article presents the course and the results of an experiment, which aimed at the subjective assessment of the multi-channel impulse responses. The assessment was conducted considering the usefulness of the received responses for the conducting operation of the digital convolution. The resulting sound material is generated for the simulation of the characteristics of the room. In a medium-sized, rectangular reverberation room (74 m^3) a number of measurements of impulse responses were conducted with the use of multi-channel microphone techniques and with the use of SoundField type microphone. In identical conditions the raw sound material was recorded (in conditions of free field). Next, the convolution was performed between the raw material and the recorded impulse responses. The group of experts, whose members had at least 5 years of experience in the field of sound engineering, was subjected to the psychoacoustic tests aiming at comparison of the sound materials achieved in the convolution and in the recording.
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.
Paper presents a numerical simulation of the acoustics of selected concert halls performed using CATT-acoustic software, and the results of acoustic measurements performed in these spaces.
In this paper, an automated measurement system was proposed that uses a probe hung below a remotely controlled balloon to measure parameters of the acoustic field in the whole volume of a room. The study was conducted to estimate distortions that such system may cause in the acoustic field at the measurement point. The most significant source of the distortions will be the buoyancy element - one large balloon or a number of smaller ones. This paper considers different spatial configurations of spherical balloons with regards to alterations they cause in the acoustic pressure levels measured below them. Interior of a room without and with a group of spherical balloons was modeled using the boundary element method. Using a larger number of smaller spheres instead of a single large one did not significantly reduce the related distortions. However, using two spheres slightly decreased distortions when the distance between the balloons and the recording point was relatively small.
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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