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1
Symulacje wyostrzania widmowego w narządzie słuchu
100%
Kleczkowski P.
Prace Naukowe Instytutu Telekomunikacji i Akustyki Politechniki Wrocławskiej. Konferencje
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2003
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tom Vol. 84, nr 28
147-152
EN
The effect of spectral ehancement in the ear has not yet been fully understood and documented, but it is an important mechanism which seems to contribute to the ear's capability of comprehending speech despite a high level of accompanying background noise. Three algorithms of spectral enhancement have been developed and tested in this work. These algorithms are not based on any physiological orpsychophysical data documenting the spectral enhancement in the ear, as they are hardly available, but they are based on arbitrary assumptions of how this mechanism may affect the time-frequency spectra of the acoustic signals. At the first stage of the simulations, input signals were analysed by the Multiple Trigonometric Bases Transform developed by this author. That analysis procedure approximates the time - frequency resolution of the ear. The main aim of the simulations proposed is to develop a tool for extracting most relevant information out of the audio signal. The examples of graphical presentations of the results of simulations and some flowcharts of the algorithms are presented.
2
Content available remote From ear modeling to auditory transform
100%
Kleczkowski P.
Archives of Acoustics
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1999
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tom Vol. 24, no. 2
191-206
EN
Understanding how the auditory system works recently gains increasing importance in audio engineering. Its most widespread practical use is in perceptual audio coders, with even more applications to be foreseen in the future. The construction of a mathematical procedure that could transform acoustic signals heard by humans to data corresponding to auditory sensation would open way to significant progress in audio engineering. In this paper the issue is discussed and important research in the field is reviewed. The proposal for a frequency analysis procedure appropriate for ear modeling is presented and verified. This procedure is a form of the Wavelet Transform.
3
Dlaczego w Polsce jest smog?
100%
Kleczkowski P.
Aura
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2020
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nr 02
PL
Stężenie zanieczyszczeń powietrza w Polsce jest wysokie w porównaniu z innymi państwami o zbliżonym poziomie życia. Specyficzne są źródła zanieczyszczeń. Stan ten jest wynikiem zaniedbań w procesie rozwoju kraju, które w niniejszym artykule zidentyfikowano. Głównym problemem jest archaiczna i do niedawna pozbawiona wszelkich norm technika grzewcza. Drugim jest struktura parku samochodowego i bardzo słaba kontrola jego stanu technicznego, zaś trzecim słaby nadzór nad emisjami z przemysłu i energetyki oraz słaba motywacja do redukcji emisji.
EN
The concentration of air pollutants in Poland is high when compared to other countries with a similar standard of living. Sources of pollution are specific. This is the effect of negligences in the process of country's development, which are identified in this paper. The main problem is an archaic heating technology, until recently not regulated by any standards. The second is the structure of all vehicles in use and very inefficient inspection of their technical condition. The third is inefficient monitoring of emissions from the industry and power supply sectors and weak motivation for the improvement of emission control technologies.
4
Content available Perception of Mixture of Musical Instruments with Spectral Overlap Removed
100%
Kleczkowski P.
Archives of Acoustics
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2012
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tom Vol. 37, No. 3
355-363
EN
The issue of auditory segregation of simultaneous sound sources has been addressed in speech research but was given less attention in musical acoustics. In perception of concurrent speech, or speech with noise, the operation of time-frequency masking was often used as a research tool. In this work, an ex- tension of time-frequency masking, leading to the removal of spectro-temporal overlap between sound sources, was applied to musical instruments playing together. The perception of the original mixture was compared with the perception of the same mixture with all spectral overlap electronically removed. Ex- periments differed in the method of listening (headphones or a loudspeaker), sets of instruments mixed, and populations of participants. The main findings were: (i) in one of the experimental conditions the re- moval of spectro-temporal overlap was imperceptible, (ii) perception of the effect increased when removal of spectro-temporal overlap was performed in larger time-frequency regions rather than in small ones, (iii) perception of the effect decreased in loudspeaker listening. The results support both the multiple looks hypothesis and the "glimpsing" hypothesis known from speech perception.
5
Dostosowanie zmodyfikowanego przekształcenia kosinusowego dla analizy sygnałów fonicznych
100%
Kleczkowski P.
Mechanika / Akademia Górniczo-Hutnicza im. St. Staszica
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2000
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tom T. 19, z. 2
193-206
PL
Zmodyfikowane przekształcenie kosinusowe jest chętnie stosowane do filtracji sygnałów fonicznych, natomiast jest mniej przydatne dla ich analizy widmowej, z uwagi na możliwy duży błąd przy interpretacji energetycznej jego wyników. Wyniki przekształcenia nie posiadają również interpretacji fazowej. W niniejszej pracy przedstawiono i zweryfikowano koncepcję dostosowania tego przekształcenia dla potrzeb analizy sygnałów fonicznych. Pierwszym elementem adaptacji jest jednoczesne zastosowanie pary przekształceń: kosinusowego i sinusowego, dzięki czemu uzyskuje się informacje o składowych widmowych w postaci "moduł i faza", podobnie jak w przekształceniu Fouriera. Dwa pozostałe elementy adaptacji mają na celu pewne zbliżenie parametrów analizy do charakterystyki narządu słuchu, co jest celowe przy analizie sygnałów, dla których narząd ten jest naturalnym odbiornikiem. Zaprojektowano specjalne okno czasowe dla tej analizy, posiadające lepszą selektywność częstotliwościową od tradycyjnie stosowanych i aproksymujące w pewnym zakresie charakterystykę tak zwanych filtrów słuchowych. Opracowano też specyficzny algorytm selekcji wyników analizy, uwypuklający te składowe dźwięku, które wykazują charakter zbliżony do tonalnego. Podano przykładowe wykresy analiz czasowo-częstotliwościowych sygnału fonicznego.
EN
The Modified Discrete Cosine Transform is often used for filtering audio signals. It is less useful for spectral analysis, because of high possible error in its estimation of energy distribution. The results of this transform also lack the phase Information. In this work the concept of adapting this transform for the analysis of audio signals is shown and verified. Its first element is the simultaneous use of a pair of cosine and sine transforms. With this, the Information on spectral components in terms of "amplitude and phase" is achieved, in a similar way as in the Fourier Transform. Two other elements of the adaptation proposed are aimed at adjusting of its parameters so that the procedure become closer to the characteristics of the ear. This can be an asset in the analysis of those signals, for which the ear is a natural receiver. The time window for such an analysis has been designed, which has better frequency selectivity than those traditionally used and also crudely approximates the characteristics of the auditory filters. The specifc algorithm for performing data selection on the results of the analysis has been developed. It enhances the tone-like components of the sound, The examples of plots of time-freguency analyses of an audio signal are presented.
6
Content available Choosing and Configuring a Stereo Microphone Technique Based on Localisation Curves
63%
Plewa M. , Kleczkowski P.
Archives of Acoustics
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2011
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tom Vol. 36, No. 2
347-363
EN
Whenever the recording engineer uses stereo microphone techniques, he/she has to consider a recording angle resulting from the positioning of microphones relative to sound sources, besides other acoustic factors. The recording angle, the width of a captured acoustic scene and the properties of a particular microphone technique are closely related. We propose a decision supporting method, based on the mapping of the actual position of a sound source to its position in the reproduced acoustic scene. This research resulted in a set of localisation curves characterising four most popular stereo microphone techniques. The curves were obtained by two methods: calculation, based on appropriate engineering formulae, and experiment consisting in the recording of sources and estimation of the perceived position in listening tests. The analysis of curves brings several conclusions important in the recording practice.
7
Content available ICA-based Single Channel Audio Separation: New Bases and Measures of Distance
63%
Mika D. , Kleczkowski P.
Archives of Acoustics
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2011
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tom Vol. 36, No. 2
311-331
EN
Independent Component Analysis (ICA) can be used for single channel audio separation, if a mixed signal is transformed into time-frequency domain and the resulting matrix of magnitude coefficients is processed by ICA. Previous works used only frequency (spectral) vectors and Kullback-Leibler distance measure for this task. New decomposition bases are proposed: time vectors and time-frequency components. The applicability of several different measures of distance of components are analysed. An algorithm for clustering of components is presented. It was tested on mixes of two and three sounds. The perceptual quality of separation obtained with the measures of distance proposed was evaluated by listening tests, indicating “beta” and “correlation” measures as the most appropriate. The “Euclidean” distance is shown to be appropriate for sounds with varying amplitudes. The perceptual effect of the amount of variance used was also evaluated.
8
Content available Reproduction of Phantom Sources Improves with Separation of Direct and Reflected Sounds
51%
Kleczkowski P. , Król A. , Małecki P.
Archives of Acoustics
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2015
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tom Vol. 40, No. 4
575--584
EN
In virtual acoustics or artificial reverberation, impulse responses can be split so that direct and reflected components of the sound field are reproduced via separate loudspeakers. The authors had investigated the perceptual effect of angular separation of those components in commonly used 5.0 and 7.0 multichannel systems, with one and three sound sources respectively (Kleczkowski et al. (2015b). In that work, each of the front channels of the 7.0 system was fed with only one sound source. In this work a similar experiment is reported, but with phantom sound sources between the front loudspeakers. The perceptual advantage of separation was found to be more consistent than in the condition of discrete sound sources. The results were analysed both for pooled listeners and in three groups, according to experience. The advantage of separation was the highest in the group of experienced listeners.
9
Surface roughness after sanding of thermally modified oak wood
51%
Wilkowski J. , Grzeskiewicz M. , Czarniak P. , Kleczkowski P.
Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology
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2011
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tom 76
EN
Surface roughness after sanding of thermally modified oak wood. In this work influence of thermal oak wood modification on quality surface after sanding with machine CNC equipped with loaf grinding bit was examined. Assesment of surface roughness parameters was realized by mean of contact profilometer. Results show that thermall modification is beneficial to surface quality after sanding. Lower values of roughness parameters were obtained for modified wood.
PL
Chropowatość powierzchni po szlifowaniu termicznie modyfikowanego drewna dębu. W pracy przeanalizowano wpływ procesu termicznej modyfikacji drewna dębu na jakość obrobionej powierzchni po szlifowaniu. Szlifowano na obrabiarce CNC ściernicami listkowymi. Oceny chropowatości powierzchni dokonywano przy pomocy profilometru stykowego. Wyniki wskazują, że modyfikacja termiczna drewna wpływa korzystnie na jakość powierzchni po szlifowaniu. Uzyskiwano niższe wartości parametrów chropowatości powierzchni drewna dębu modyfikowanego.
10
Content available Lombard Effect in Polish Speech and its Comparison in English Speech
51%
Kleczkowski P. , Żak A. , Król-Nowak A.
Archives of Acoustics
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2017
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tom Vol. 42, No. 4
561--569
EN
The first extensive investigation on the Lombard effect with Polish speech has been performed. Characteristic parameters of Lombard speech were measured: intensity, fundamental frequency, spectral tilt, duration of words, duration of pauses and duration of vowels. The effect was investigated in a task involving real communication – solving a Sudoku puzzle. The speakers produced speech in quiet and in three different backgrounds: competing speech, speech-shaped noise and speech-modulated noise. The experimental conditions were held as close as possible to those in the study by Cooke and Lu (2010) so that conclusions could be drawn whether differences between the Lombard effect in Polish speech and English speech existed. Most of the findings on the Lombard effect known from the literature have been confirmed with Polish speech. In three parameters, Polish speakers were more sensitive to modulated backgrounds while English speakers were more sensitive to a stationary background. In both languages, the modulated backgrounds induced speakers to extend pauses in the communication tasks.
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