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1
Content available remote

Reliability of Sound Field Simulations

100%
Wierzbicki J.
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issue 1
183-185
EN
One of the most important questions in sound field modelling is connected with the reliability of results. The absolute accuracy of values predicted by the software is very difficult to quantify because of an uncertainty in the measurements. But it is possible to determine an influence of the input data accuracy and calculation parameters on the obtained results. Problems and differences in the sound field simulation results are presented in the hereby paper. Test procedures of the sound filed simulation software and also well-documented exemplary objects in an open space will be the main aim of investigations.
2
Content available remote

Localization of the Sound Source with the Use of the First-order Ambisconic Microphone

51%
Wierzbicki J., Małecki P., Wiciak J.
Acta Physica Polonica A
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2013
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vol. 123
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issue 6
1114-1117
EN
The paper presents results of determination of sound wave direction based on signals from first-order ambisonic microphone. The experiment consisted in recording the test signals with the SoundField microphone positioned in the axis of the turntable in the anechoic chamber. The spherical coordinates of the sound intensity vector were calculated with use of three different conceptual and numerical approaches and were compared to actual values resulting from the geometry of the system. Accuracy of the localization of the sound source depending on the frequencies and the method for determination of the spherical coordinates as well as on the time constant and the parameters of the signal recording was presented. The obtained results show the effectiveness of the calculation methods used for localization of the sound source.
3
Content available remote

Feed Forward Neural Network for Autofluorescence Imaging Classification

51%
Kulas Z., Bereś-Pawlik E., Wierzbicki J.
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issue 6
1189-1193
EN
The key elements in cancer diagnostics are the early identification and estimation of the tumor growth and its spread in order to determine the area to be operated on. The aim of our study was to develop new methods of analyzing autofluorescence images which will allow us an objective and accurate assessment of the location of a tumor and will also be helpful in determining the advancement of the disease. The proposed classification methods are based on neural network algorithms. An Olympus company endoscopic system was used for an autofluorescence intestine imaging study. The autofluorescence imaging analysis process can be divided into several main stages. The first step is preparation of a training data set. The second one involves selection of feature space, namely the selection of those features which enable distinguishing the pathologically altered areas from the healthy ones. Final stages of the analysis include pathologically changed tissue classification and diagnosis.
4
Content available remote

Subjective Assessment of the Multi-Channel Auralizations

51%
Małecki P., Wiciak J., Wierzbicki J.
Acta Physica Polonica A
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2012
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vol. 121
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issue 1A
A-110-A-114
EN
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.
5
Content available remote

Quietness in the Soundscape of the Białowieża National Park

39%
Wiciak J., Mleczko D., Ozga A., Wszołek G., Wierzbicki J., Piechowicz J., Małecki P.
Acta Physica Polonica A
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2015
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vol. 128
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issue 1A
A-79-A-84
EN
The quietness, defined as the near or complete absence of sound, in the context of the natural environment protection, may be considered a state in which no undesired of foreign sounds occur, and, by analogy to noise, analyzed in two aspects: that pertaining to measurements and the subjective one. The article discusses the lowest levels of sounds recorded at night in the soundscape of the Białowieża Forest. Due to low levels of the examined sounds and the technical problems that occurred while the sounds were being measured and registered, the acoustic examination of the measurement set-up in an anechoic chamber has also been presented. The research is aimed at defining precisely the concept of quietness prevailing in the nature in the subjective aspect by determining both the range of levels and the characteristics of preferred sounds.
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