Contents of issue 1, vol. 29 (2004)

  1. M. Dziubiński, B. Kostek, High accuracy and octave error immune pitch detection algorithms, Archives of Acoustics, 29, 1, 3-23
  2. A. Sęk, E. Skrodzka, E. Ozimek, A. Wicher, Intelligibility of speech processed by a spectral contrast enhancement procedure and a binaural procedure, Archives of Acoustics, 29, 1, 25-34
  3. C. Pastiadis, G. Papanikolaou, Discrete cosine transform based de-noising of glottal pulses, Archives of Acoustics, 29, 1, 35-43
  4. Z. Engel, K. Kosała, Reverberation indices in acoustic assessments of sacral structures, Archives of Acoustics, 29, 1, 45-60
  5. H. Łopacz, R. Marczuk, A new approach to the room impulse response simulation, Archives of Acoustics, 29, 1, 61-85
  6. I. Trots, A. Nowicki, W. Secomski, J. Litniewski, Golay sequences - side-lobe - canceling codes for ultrasonography, Archives of Acoustics, 29, 1, 87-97
  7. W. Laprus, E. Danicki, Piezoelectric guided wave propagation, Archives of Acoustics, 29, 1, 99-105
  8. M. Meissner, The response of Helmholtz resonator to external excitation. Part I: Acoustically induced resonance, Archives of Acoustics, 29, 1, 107-121
  9. Technical Notes - J.A. Ferreira, F.B. Diniz, A. Ferreira, P.H.T. Zannin, Evaluation of acoustical parameters of a Brazilian popular housing model, Archives of Acoustics, 29, 1, 123-127
  10. Chronicle, The X-th International Symposium on Sound Engineering and Tonmeistering, Archives of Acoustics, 29, 1, 129-139
  11. Chronicle, Doctor's Thesis, Archives of Acoustics, 29, 1, 141
M. Dziubiński, B. Kostek, High accuracy and octave error immune pitch detection algorithms
Multimedia Systems Department
Gdańsk University of Technology
Narutowicza 11/12, 80-952 Gdańsk, Poland
e-mail: kido@sound.eti.pg.gda.pl
The aim of this paper is to present a method improving pitch estimation accuracy, showing high performance for both synthetic harmonic signals and musical instrument sounds. This method employs an Artificial Neural Network of a feed-forward type. In addition, octave error optimized pitch detection algorithm, based on spectral analysis is introduced. The proposed algorithm is very effective for signals with strong harmonic, as well as nearly sinusoidal contents. Experiments were performed on a variety of musical instrument sounds and sample results exemplifying main issues of both engineered algorithms are shown.

A. Sęk, E. Skrodzka, E. Ozimek, A. Wicher, Intelligibility of speech processed by a spectral contrast enhancement procedure and a binaural procedure
Institute of Acoustics, Adam Mickiewicz University
Umultowska 85, 60-614 Poznań, Poland
e-mail: oleksek@amu.edu.pl
The study reported was undertaken as an attempt to improve the intelligibility of selected speech signals (numerical test) masked by a speech-shaped noise, by a proposed algorithm of the speech signal processing based on the spectral contrast enhancement and binaural procedure. The spectral contrast enhancement involved the transformation of the speech signal spectrum to achieve an increase in the level of the amplitude between subsequent minima and maxima of individual formants. The binaural procedure involved the determination of the interaural time difference (ITD) and the interaural intensity difference (IID) in order to select and enhance the fragments reaching the listener from the front. The intelligibility of speech processed by the algorithm was compared to that of the unprocessed speech for different spatial separations between the signal and the noise sources and for a few signal to noise ratios. The results have shown that the intelligibility of the speech presented against the noise significantly depends on the angle between the directions of the signal and the noise. The intelligibility of speech is much larger when the noise and the speech reach the observer from different directions, i.e. when their sources are spatially separated. In general, the algorithm improves the intelligibility of numerical tests presented at the background of the noise by a few percent and the greatest improvement has been observed for low signal to noise ratios. The algorithm performance was different for each hearing impaired subject with binaural hearing loss. To get an objective assessment of the algorithm performance it should be optimised and tested on a larger group of subjects for more diverse sound material.


C. Pastiadis, G. Papanikolaou, Discrete cosine transform based de-noising of glottal pulses
Laboratory of Electroacoustics
Electrical and Computer Engineering Dept., Polytechnic School
Aristotle University of Thessaloniki, Greece
e-mail: pastiadi@egnatia.ee.auth.gr
Reliable estimates of the glottal function are of major importance in speech/voice processing for the characterization of voicing conditions, description of various phonation types, and identification of their parameters. This paper presents a new method for de-noising glottal wavelets (Differentiated Glottal Volume Velocity Pulses) and separation of the noise component, based on an approximation of their Discrete Cosine Transform as a sum of Exponentially Damped Sinusoids. The identification of the Exponentials' parameters leads to convenient estimation of ''clean'' glottal wavelets and thus separation of noise disturbances. The method is compared to standard Low-pass filtering and Wavelet de-noising using Monte Carlo simulations on synthetic Liljencrants-Fant glottal pulse models. As shown, the method supercedes for lower SNRs. Moreover, the method does not require exact determination of control parameters thus offering ease of implementation.


Z. Engel, K. Kosała, Reverberation indices in acoustic assessments of sacral structures
Department of Mechanics and Vibroacoustics
University of Science and Technology (AGH)
30-059 Kraków, Al. Mickiewicza 30, Poland
The proposition of the acoustic assessment of interiors of sacral buildings by means of the single-numbered, global index of acoustic quality was given in this paper. The introduction of a uniform method is justified since none of the available methods addresses to a sufficient degree to the specificity of such interiors. The main partial index - the reverberation index - was discussed and applied to the tests in several catholic churches, where acoustic measurements were performed. The continuation of the research presented here will lead to the development of a new method especially suitable for the acoustic quality assessment of sacral buildings.


H. Łopacz, R. Marczuk, A new approach to the room impulse response simulation
University of Science and Technology (AGH)
Department of Mechanics and Vibroacoustics
Al. Mickiewicza 30, 30-059 Kraków, Poland
e-mail: lopacz@agh.edu.pl; marczuk@agh.edu.pl
The most important problem of room acoustics is the evaluation of the acoustic quality of projected and modernized rooms. To this end it is necessary to work out a calculating impulse response algorithm for a digital room model. The virtual rooms impulse response manners of modeling are described in the article. The impulse response synthetic models have been evaluated on the basis of selected numerical factors and a simple auditory test. Thanks to the impulse response calculation it is possible to evaluate the subjective and objective room acoustic properties and hence to run the room simulation tests (the sound sources configuration, the room planning) in order to reach optimal solutions, which meet a given criterion. The problems described are related to the ''virtual sound space'' concept. Intuitively, we mean by this a sound reality model, which enables, on the basis of the model and measurement data, an audio impressions simulation of the existing and being under projection acoustic systems. A basic process, which enables the sound reception, is the test signal and the impulse response convolution.


I. Trots, A. Nowicki, W. Secomski, J. Litniewski, Golay sequences - side-lobe - canceling codes for ultrasonography
Institute of Fundamental Technological Research
Polish Academy of Sciences
Świętokrzyska 21, 00-049 Warszawa, Poland
e-mail: igortr@ippt.gov.pl
In this paper three different methods and algorithms used to calculate the pairs of Golay sequences of the different length are described. The program for simulating the pairs of the Golay sequences of different length is given. This program (using Matlab™ routines) is based on the basic properties of complementary series and is simple and computationally effective. Experimental results are presented in the form, which in a clear way illustrates the resolution, depth penetration and contrast dynamics of ultrasonic images obtained using the Golay coded excitation.


W. Laprus, E. Danicki, Piezoelectric guided wave propagation
Institute of Fundamental Technological Research
Polish Academy of Sciences
Świętokrzyska 21, 00-049 Warszawa, Poland
A perfectly conducting strip embedded in a piezoelectric medium is considered. Waves propagating along the strip are investigated with the use of a surface impedance function which is suggested by the known surface impedance function for a perfectly conducting plane embedded in the medium. A dispersion equation for the waves is found and solved in the case of a narrow strip.


M. Meissner, The response of Helmholtz resonator to external excitation. Part I: Acoustically induced resonance
Institute of Fundamental Technological Research
Polish Academy of Sciences
Świętokrzyska 21, 00-049 Warszawa, Poland
e-mail: mmeissn@ippt.gov.pl
The first of two companion papers theoretical and experimental results are presented for a Helmholtz resonator subject to external excitation by an acoustic plane wave. The response of the resonator was analysed in terms of the relation between the pressure induced in the interior of the resonator and the driving pressure. Equations for the resonance frequency and the quality factor were developed for the cavity that was a rectangular parallelepiped with a centered circular orifice. The flow from the cavity had a constant velocity profile. The resonator was modelled by an equivalent impedance circuit, predicted from the classic theory of sound radiation, with an additional resistive term connected with the viscous action inside the orifice. The theoretical results were compared with experimental data for a frequency chosen so as to tune the system to the lowest resonance mode. The experiment has shown that the acoustic response of resonator was changed considerably when mechanical vibrations of the resonator elements were excited. A phenomenon of flow-induced resonance in the considered system geometry will be presented in the companion paper.


Technical Notes - J.A. Ferreira, F.B. Diniz, A. Ferreira, P.H.T. Zannin, Evaluation of acoustical parameters of a Brazilian popular housing model
Laboratory of Environmental Acoustics
Federal University of Paraná, Centro Politécnico, Dept. de Eng. Mecânica
Jardim das Américas, Curitiba, PR
e-mail: jaugusto@demec.ufpr.br
The present survey shows the results obtained from the evaluation of the acoustical parameters in situ, through standardized measurements, inside a popular residence designed to offer an option to combat the housing deficit of the low income Brazilian population.
Key words: acoustical insulation index, popular houses.


Chronicle, The X-th International Symposium on Sound Engineering and Tonmeistering
From 11-th to 13-th of September 2003 at Wrocław University of Technology, the X-th International Symposium on Sound Engineering and Tonmeistering was held with more than 60 participants. It was organized by Polish Section of AES with cooperation of Institute of Telecommunications and Acoustics. The representatives of 5 academic centers from Poland presented 29 papers on digital audio, psychoacoustics, electroacoustics, room acoustics and speech. During the Symposium, the radio workshop at Polish Radio Wrocław, and the exhibition of the newest electroacoustical devices made by YAMAHA Corporation were organized. As a part of this Symposium the meeting of Polish Section of AES took place and new officers of the section were elected. At one of social events there was a chance to participate in the concert of the 38-th International Festival Wratislavia Cantans which featured Collegium Vocale Gent and Prometheus Ensemble (from Belgium) conducted by Philippe Herreweghe.


Chronicle, Doctor's thesis: Reverberation time of rectangular rooms with non-uniformly distributed absorption [in English] - 2003
by Reinhard O. Neubauer Ingenieurburo fur Bauphysik und Akustik,
Theresienstrasse 28,
85049 Ingolstadt, Germany
Supervisor: Dr hab. Bożena Kostek
Reviewers: Prof. Zbigniew Engel
Prof. Andrzej Rakowski
Prof. Jerzy Sadowski
Abstract: In this work, a review of the well-known reverberation time formulae is given and recent developments of reverberation time equations are investigated. A modified Fitzroy formula for estimating the reverberation time in rooms with non-uniformly distributed sound absorption is introduced and thoroughly analysed. As in many practical cases Sabine's or Eyring's reverberation time formula is used, it may be regularly observed that the predicted reverberation time does not conform with the measured reverberation time. Sabine's formula, as well as other classical reverberation equations such as Eyring's or Millington-Sette's formulae are thought not to provide results of predicted reverberation times for room conditions accurately, where the sound absorption is not uniformly distributed. This work is devoted to the problem of a more accurate calculation of the reverberation time with non-uniformly distributed absorption in the room. The Modified Fitzroy Formula results are closer to those measured in real halls. In real rooms, the Modified Fitzroy Formula may therefore become a useful design tool for estimating reverberation time. A modification of Eyring's as well as Fitzroy's equations yielding the Modified Fitzroy Formula is discussed in this work and some practical examples, which compare predicted and measured values of reverberation time in real rooms, are presented. Finally, the New Formula is introduced and compared with other RT-based calculations.
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Last updated: February, 2004