Rok 2024

• Performance of the Direct Sequence Spread Spectrum Underwater Acoustic Communication System with Differential Detection in Strong Multipath Propagation Conditions

  Publikacja

  • J. Schmidt
  • I. Kochańska
  • A. Schmidt

  - Archives of Acoustics - Rok 2024

  The underwater acoustic communication (UAC) operating in very shallow-water should ensure reliable transmission in conditions of strong multipath propagation, significantly disturbing the received signal. One of the techniques to achieve this goal is the direct sequence spread spectrum (DSSS) technique, which consists in binary phase shift keying (BPSK) according to a pseudo-random spreading sequence. This paper describes the DSSS...

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Rok 2023

• Quality Evaluation of Speech Transmission via Two-way BPL-PLC Voice Communication System in an Underground Mine

  Publikacja

  • P. Falkowski-Gilski
  • G. Debita

  - Archives of Acoustics - Rok 2023

  In order to design a stable and reliable voice communication system, it is essential to know how many resources are necessary for conveying quality content. These parameters may include objective quality of service (QoS) metrics, such as: available bandwidth, bit error rate (BER), delay, latency as well as subjective quality of experience (QoE) related to user expectations. QoE is expressed as clarity of speech and the ability...

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Rok 2022

• Pursuing Listeners’ Perceptual Response in Audio-Visual Interactions - Headphones vs Loudspeakers: A Case Study

  Publikacja

  • B. Mróz
  • B. Kostek

  - Archives of Acoustics - Rok 2022

  This study investigates listeners’ perceptual responses in audio-visual interactions concerning binaural spatial audio. Audio stimuli are coupled with or without visual cues to the listeners. The subjective test participants are tasked to indicate the direction of the incoming sound while listening to the audio stimulus via loudspeakers or headphones with the head-related transfer function (HRTF) plugin. First, the methodology...

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• Acoustic Hysteresis in Flows with Different Kinds of Relaxation and Attenuation

  Publikacja

  • A. Perelomova

  - Archives of Acoustics - Rok 2022

  Graphs in the thermodynamic plane acoustic pressure versus excess acoustic density representing acoustic hysteresis, are considered as indicators of relaxation processes, equilibrium parameters of a flow, and kinds of wave exciters. Some flows with deviation from adiabaticity are examined: the Newtonian flow of a thermocon- ducting gas, the flow of a gas with vibrational relaxation, the flow of liquid electrolyte with a chemical...

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• About Unusual Diffraction and Thermal Self-Action of Magnetosonic Beam

  Publikacja

  • A. Perelomova

  - Archives of Acoustics - Rok 2022

  The dynamics of slightly diverging two-dimensional beams whose direction forms a constant angle θ with the equilibrium straight magnetic strength is considered. The approximate dispersion relations and corresponding links which specify hydrodynamic perturbations in confined beams are derived. The study is dedicated to the diffraction of a magnetosonic beam and nonlinear thermal self-action of a beam in a thermoconducting gaseous plasma....

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Rok 2021

• Numerical Model of Surface and Quasi-Spherical Sea Noise and Its Application to Analysis of DIFAR Systems

  Publikacja

  • M. Rudnicki
  • R. Salamon
  • J. Marszal

  - Archives of Acoustics - Rok 2021

  Various types of passive sonar systems are used to detect submarines. These activities are complex and demanding. Therefore, computer simulations are most often used at the design stage of these systems. For this reason, it is also necessary to simulate the acoustic ambient noise of the sea. The article proposes a new numerical model of surface and quasi-spherical sea noise and presents its statistical parameters. The results of...

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• Nonlinear Interaction of Magnetoacoustic Modes in a Quasi-Isentropic Plasma Flow

  Publikacja

  • A. Perelomova

  - Archives of Acoustics - Rok 2021

  The nonlinear interaction of magnetoacoustic waves in a plasma is analytically studied. A plasma is an open system. It is affected by the straight constant equilibrium magnetic flux density forming constant angle with the wave vector which varies from 0 till . The nonlinear instantaneous equation which describes excitation of secondary wave modes in the field of intense magnetoacoustic perturbations is derived by use of projecting....

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• Magnetosonic Excitation of the Entropy Perturbations in a Plasma with Thermal Conduction Depending on Temperature

  Publikacja

  • A. Perelomova

  - Archives of Acoustics - Rok 2021

  Nonlinear excitation of the entropy perturbations by magnetosonic waves in a uniform and infinite plasma model is considered. The wave vector of slow or fast mode forms an arbitrary angle (0 B B ) with the equilibrium straight magnetic field, and all perturbations are functions of the time and longitudinal coordinate. Thermal conduction is the only factor which destroys isentropicity of wave perturbations and causes the nonlinear...

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Rok 2020

• Shallow Water Experiment of OFDM Underwater Acoustic Communications

  Publikacja

  • I. Kochańska
  • J. Schmidt
  • J. Marszal

  - Archives of Acoustics - Rok 2020

  The large variability of communication properties of underwater acoustic channels, and especially the strongly varying instantaneous conditions in shallow waters, is a challenge for the designers of underwater acoustic communication (UAC) systems. The use of phase modulated signals does not allow reliable data transmission through such a tough communication channel. However, orthogonal frequency-division multiplexing (OFDM), being...

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• On the Consumption of Multimedia Content Using Mobile Devices: a Year to Year User Case Study

  Publikacja

  • P. Falkowski-Gilski

  - Archives of Acoustics - Rok 2020

  In the early days, consumption of multimedia content related with audio signals was only possible in a stationary manner. The music player was located at home, with a necessary physical drive. An alternative way for an individual was to attend a live performance at a concert hall or host a private concert at home. To sum up, audio-visual effects were only reserved for a narrow group of recipients. Today, thanks to portable players,...

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• Non-Linear Interaction of Harmonic Waves in a Quasi-Isentropic Flow of Magnetic Gas

  Publikacja

  • A. Perelomova

  - Archives of Acoustics - Rok 2020

  The diversity of wave modes in the magnetic gas gives rise to a wide variety of nonlinear phenomenaassociated with these modes. We focus on the planar fast and slow magnetosound waves in the geometryof a flow where the wave vector forms an arbitrary angleθwith the equilibrium straight magnetic field.Nonlinear distortions of a modulated signal in the magnetic gas are considered and compared to thatin unmagnetised gas. The case of...

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• Magnetoacoustic Heating of Plasma Caused by Periodic MagnetosoundPerturbations with Discontinuities in a Quasi-Isentropic Magnetic Gas

  Publikacja

  • A. Perelomova

  - Archives of Acoustics - Rok 2020

  The magnetoacoustic heating of plasma by harmonic or periodic saw-tooth perturbations at a trans-ducer is theoretically studied. The planar fast and slow magnetosound waves are considered. The wavevector may form an arbitrary angleθwith the equilibrium straight magnetic field. In view of variableθand plasma-β, the description of magnetosound perturbations and appropriate magnetosound heatingis fairly difficult. The scenario of...

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• Impact of Spatial Noise Correlation on Bearing Accuracy in DIFAR Systems

  Publikacja

  • M. Rudnicki
  • J. Marszal
  • R. Salamon

  - Archives of Acoustics - Rok 2020

  DIFAR type underwater passive systems are one of the more commonly used tools for detecting submarines. At the design stage, which usually uses computer simulations, it is necessary to generate acoustic noise of the sea. It has been shown that correlating noise significantly reduces these errors compared to the assumption that noise is uncorrelated. In addition, bearing errors have been shown to be the same in systems with a commonly...

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Rok 2019

• Sound engineering as our commitment to its creators in Poland

  Publikacja

  • B. Kostek
  • A. Czyżewski

  - Archives of Acoustics - Rok 2019

  Sound engineering is an interdisciplinary and rapidly expanding domain. It covers many aspects, such as sound perception, studio and sound mastering technology, music information retrieval including content-based search systems and automatic music transcription frameworks, sound synthesis, sound restoration, electroacoustics, and other ones constituting multimedia technology. Moreover, machine learning methods applied to the topics...

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• Nonlinear Interaction of Modes in a Planar Flow of a Gas with Viscous and Thermal Attenuation

  Publikacja

  • A. Perelomova

  - Archives of Acoustics - Rok 2019

  The nonlinear interaction of wave and non-wave modes in a gas planar flow are considered. Attention is mainly paid to the case when one sound mode is dominant and excites the counter-propagating sound mode and the entropy mode. The modes are determined by links between perturbations of pressure, density, and fluid velocity. This definition follows from the linear conservation equations in the differential form and thermodynamic...

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• Modelling and Measurement of Folk Guitar: Truss Rod and Strings in Numerical Analysis of Tone

  Publikacja

  • P. M. Bielski
  • M. Kujawa
  • I. Lubowiecka

  - Archives of Acoustics - Rok 2019

  The study makes an attempt to model a complete vibrating guitar including its non-linear features, specifically the tension-compression of truss rod and tension of strings. The purpose of such a model is to examine the influence of design parameters on tone. Most experimental studies are flawed by uncertainties introduced by materials and assembly of an instrument. Since numerical modelling of instruments allows for deterministic...

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• Impact of Boundary Conditions on Acoustic Excitation of EntropyPerturbations in a Bounded Volume of Newtonian Gas

  Publikacja

  • A. Perelomova

  - Archives of Acoustics - Rok 2019

  Excitation of the entropy mode in the field of intense sound, that is, acoustic heating, is theoreticallyconsidered in this work. The dynamic equation for an excess density which specifies the entropy mode,has been obtained by means of the method of projections. It takes the form of the diffusion equation withan acoustic driving force which is quadratically nonlinear in the leading order. The diffusion coefficient isproportional...

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• Developing assumptions for the tram noise attenuation passive system using the noise maps analysis method

  Publikacja

  • T. Nowakowski

  - Archives of Acoustics - Rok 2019

  The paper presents experimental research carried out to determine the possible actions to reduce thenoise generated by trams in a highly urbanised area. A few design strategies affecting tram ride qualityhave been presented – especially in the aspect of the acoustic phenomena. Main sources of the noisein trams were characterised. The paper includes selected results of comprehensive...

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• Comparison of Lithuanian and Polish Consonant Phonemes Based on Acoustic Analysis – Preliminary Results

  Publikacja

  • G. Korvel
  • O. Kurasova
  • B. Kostek

  - Archives of Acoustics - Rok 2019

  The goal of this research is to find a set of acoustic parameters that are related to differences between Polish and Lithuanian language consonants. In order to identify these differences, an acoustic analysis is performed, and the phoneme sounds are described as the vectors of acoustic parameters. Parameters known from the speech domain as well as those from the music information retrieval area are employed. These parameters are...

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• Assessment of the Effectiveness of a Short-term Hearing Aid Use in Patients with Different Degrees of Hearing Loss

  Publikacja

  • T. Poremski
  • P. Szymański
  • B. Kostek

  - Archives of Acoustics - Rok 2019

  The study presents evaluating the effectiveness of the hearing aid fitting process in the short-term use (7 days). The evaluation method consists of a survey based on the APHAB (Abbreviated Profile of Hearing Aid Benefit) questionnaire. Additional criteria such as a degree of hearing loss, number of hours and days of hearing aid use as well as the user’s experience were also taken into consideration. The outcomes of the benefit...

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Rok 2018

• Nonlinear Excitation of the Non-Wave Perturbations by the Magnetoacoustic Waves in the Non-Isentropic Plasma

  Publikacja

  • A. Perelomova

  - Archives of Acoustics - Rok 2018

  Nonlinear excitation of slow modes by the planar magnetosonic perturbations in a plasma is discussed. Plasma is an open system due to radiation and external heating. This may stipulate enhancement of wave perturbations and hence the acoustical activity of plasma. Plasma is assumed to be a homogeneous ideal gas with infinite electrical conductivity. The straight magnetic field is orthogonal to the velocity of fluid’s...

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• In Memoriam Professors Marianna Sankiewicz-Budzyński and Gustaw K.E. Budzyński - Founders of the Polish Audio Engineering

  Publikacja

  • A. Czyżewski
  • B. Kostek

  - Archives of Acoustics - Rok 2018

  Biography and scientific achievements of Professors Marianna Sankiewicz-Budzyński and Gustaw K.E. Budzyński - Founders of the Polish Audio Engineering.

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• Decomposition of Acoustic and Entropy Modes in a Non-Isothermal Gas Affected by a Mass Force

  Publikacja

  • A. Perelomova
  • S. Leble

  - Archives of Acoustics - Rok 2018

  Diagnostics and decomposition of atmospheric disturbances in a planar flow are considered in this work. The study examines a situation in which the stationary equilibrium temperature of a gas may depend on the vertical coordinate due to external forces. The relations connecting perturbations are analytically established. These perturbations specify acoustic and entropy modes in an arbitrary stratified gas affected by a constant...

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• A study on of music features derived from audio recordings examples – a quantitative analysis

  Publikacja

  • A. Dorochowicz
  • B. Kostek

  - Archives of Acoustics - Rok 2018

  The paper presents a comparative study of music features derived from audio recordings, i.e. the same music pieces but representing different music genres, excerpts performed by different musicians, and songs performed by a musician, whose style evolved over time. Firstly, the origin and the background of the division of music genres were shortly presented. Then, several objective parameters of an audio signal were recalled that...

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Rok 2017

• Voiceless Stop Consonant Modelling and Synthesis Framework Based on MISO Dynamic System

  Publikacja

  • G. Korvel
  • B. Kostek

  - Archives of Acoustics - Rok 2017

  A voiceless stop consonant phoneme modelling and synthesis framework based on a phoneme modelling in low-frequency range and high-frequency range separately is proposed. The phoneme signal is decomposed into the sums of simpler basic components and described as the output of a linear multiple-input and single-output (MISO) system. The impulse response of each channel is a third order quasi-polynomial. Using this framework, the...

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• Subjective and Objective Comparative Study of DAB+ Broadcast System

  Publikacja

  • P. Falkowski-Gilski
  • J. Stefański

  - Archives of Acoustics - Rok 2017

  Broadcasting services seek to optimize their use of bandwidth in order to maximize user’s quality of experience. They aim to transmit high-quality digital speech and music signals at the lowest bitrate. They intend to offer the best quality under available conditions. Due to bandwidth limitations, audio quality is in conflict with the number of transmitted radio programs. This paper analyzes whether the quality of real-time digital...

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• Standing Waves in One-Dimensional Resonator Contaning an Ideal Isothermal Gas Affected by the Constant Mass Force

  Publikacja

  • A. Perelomova

  - Archives of Acoustics - Rok 2017

  The study is devoted to standing acoustic waves in one-dimensional planar resonator which containing an ideal gas. A gas is affected by the constant mass force. Two types of physically justified boundary conditions are considered: zero velocity or zero excess pressure at both boundaries. The variety of nodal and antinodal points is determined. The conclusion is that the nodes of pressure and antinodes of velocity do not longer...

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• Sound intensity distribution around organ pipe

  Publikacja

  • P. Odya
  • J. Kotus
  • M. Szczodrak
  • B. Kostek

  - Archives of Acoustics - Rok 2017

  The aim of the paper was to compare acoustic field around the open and stopped organ pipes. The wooden organ pipe was located in the anechoic chamber and activated with a constant air flow, produced by an external air-compressor. Thus, long-term steady state response was possible to obtain. Multichannel acoustic vector sensor was used to measure the sound intensity distribution of radiated acoustic energy. Measurements have been...

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• DAB vs DAB+ Radio Broadcasting: a Subjective Comparative Study

  Publikacja

  • P. Falkowski-Gilski

  - Archives of Acoustics - Rok 2017

  In the age of digital media, delivering high quality content to consumers is one of the most demanding tasks. There exist numerous broadcasting standards, with different pros and cons, and the DAB/DAB (Digital Audio Broadcasting) system is one of the most popular among them. From an engineer’s perspective, efficient resource management under limited bandwidth conditions has always been a challenge. In this paper a subjective quality...

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Rok 2016

• Standing Waves in a Rectangular Resonator Containing Acoustically Active Gases

  Publikacja

  • A. Perelomova

  - Archives of Acoustics - Rok 2016

  The distribution of perturbations of pressure and velocity in a rectangular resonator is considered. A resonator contains a gas where thermodynamic processes take place, such as exothermic chemical reaction or excitation of vibrational degrees of a molecule’s freedom. These processes make the gas acoustically active under some conditions. We conclude that the incident and reflected compounds of a sound beam do not interact in the...

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• Performance of Noise Map Service Working in Cloud Computing Environment

  Publikacja

  • K. Marciniuk
  • M. Szczodrak
  • B. Kostek

  - Archives of Acoustics - Rok 2016

  In the paper a noise map service designated for the user interested in environmental noise subject is presented. It is based on cloud computing. Noise prediction algorithm and source model, developed for creating acoustic maps, are working in cloud computing environment. In the study issues related to noise modeling of sound propagation in urban spaces are discussed with a special focus on road noise. Examples of results obtained...

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• On the Nonlinea Distortions of Sound and its Coupling with Other Modes in a Gasesous Plasma with Finite Electric Conductivity in a Magnetic Field

  Publikacja

  • A. Perelomova

  - Archives of Acoustics - Rok 2016

  Nonlinear phenomena of the planar and quasi-planar magnetoacoustic waves are considered. We focus on deriving of equations which govern nonlinear excitation of the non-wave motions by the intense sound in initially static gaseous plasma. The plasma is treated as an ideal gas with finite electrical conductivity permeated by a magnetic field orthogonal to the trajectories of gas particles. This introduces dispersion of a flow. Magnetoacoustic...

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• Mutual Clutter Suppression Techniques for FM Sonars

  Publikacja

  • J. Marszal
  • M. Rudnicki
  • A. Jedel
  • R. Salamon
  • I. Kochańska

  - Archives of Acoustics - Rok 2016

  The article presents methods that help in the elimination of mutual clutter as well as the consequences of two FM sounding signal sonars operating in the same body of water and frequency band. An in-depth analysis of mutual clutter was carried out. The effects of sounding signal differentiation were determined, as was the Doppler effect on mutual clutter suppression. One of the methods analysed is of particular interest in a situation...

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• Modeling and Designing Acoustical Conditions of the Interior – Case Study

  Publikacja

  • B. Kostek
  • S. Laskowski
  • K. Mizgier

  - Archives of Acoustics - Rok 2016

  The primary aim of this research study was to model acoustic conditions of the Courtyard of the Gdańsk University of Technology Main Building, and then to design a sound reinforcement system for this interior. First, results of measurements of the parameters of the acoustic field are presented. Then, the comparison between measured and predicted values using the ODEON program is shown. Collected data indicate a long reverberation...

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• Loudness Scaling Test Based on Categorical Perception

  Publikacja

  • B. Kostek
  • P. Odya
  • P. Suchomski

  - Archives of Acoustics - Rok 2016

  The main goal of this research study is focused on creating a method for loudness scaling based on categorical perception. Its main features, such as: way of testing, calibration procedure for securing reliable results, employing natural test stimuli, etc., are described in the paper and assessed against a procedure that uses 1/2-octave bands of noise (LGOB) for the loudness growth estimation. The Mann-Whitney U-test is employed...

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• Can Historic Interiors with Large Cubature be Turned Acoustically Correct?

  Publikacja

  • T. Kamisiński
  • A. Kulowski
  • R. Kinasz

  - Archives of Acoustics - Rok 2016

  Historic interiors with large cubature, such as reception, theatrical, and concert halls, need to be renovated periodically if they are to be preserved as cultural heritage for future generations. In such cases it is necessary to maintain appropriate balance between requirements imposed by heritage conservation authorities office which are usually being given a higher priority, applicable safety regulations, and the comfort of...

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• 3D Acoustic Field Intensity Probe Design and Measurements

  Publikacja

  • J. Kotus
  • A. Czyżewski
  • B. Kostek

  - Archives of Acoustics - Rok 2016

  The aim of this paper is two-fold. First, some basic notions on acoustic field intensity and its measurement are shortly recalled. Then, the equipment and the measurement procedure used in the sound intensity in the performed research study are described. The second goal is to present details of the design of the engineered 3D intensity probe, as well as the algorithms developed and applied for that purpose. Results of the intensity...

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Rok 2015

• Thermal Self-Action of Acoustic Beams Containing Several Shock Fronts

  Publikacja

  • A. Perelomova

  - Archives of Acoustics - Rok 2015

  Thermal self-action of an acoustic beam with one discontinuity or several shock fronts is studied in a Newtonian fluid. The stationary self-action of a single sawtooth wave with discontinuity (or some integer number of these waves), symmetric or asymmetric, is considered in the cases of self-focusing and self- defocusing media. The results are compared with the non-stationary thermal self-action of the periodic sound. Thermal self-action...

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• Study of Noise Propagation for Small Vessels

  Publikacja

  • M. Weryk
  • E. Kozaczka
  • G. Grelowska

  - Archives of Acoustics - Rok 2015

  The paper presents the results of the noise propagation analysis in ship structures tested in a number of AHTS (Anchor Handling Tug Supply) vessels. Statistical Energy Analysis (SEA) based on numerical model developed specially for the purpose of this numerical investigation were conducted. This numerical model enabled the analysis of both the structural elements and the acoustic spaces. For the detailed studies 47 points fixed...

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• Nonlinear properties of the Gotland Deep – Baltic Sea

  Publikacja

  • G. Grelowska
  • E. Kozaczka

  - Archives of Acoustics - Rok 2015

  The properties of the nonlinear phenomenon in water, including sea water, have been well known for many decades. The feature of the non homogeneous distribution of the speed of sound along the depth of the sea is very interesting from the physical and technical point of view. It is important especially in the observation of underwater area by means of acoustical method ( Grelowska et al ., 2013; 2014). The observation of the underwater...

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• Music Mood Visualization Using Self-Organizing Maps

  Publikacja

  • M. Piotrowska
  • B. Kostek

  - Archives of Acoustics - Rok 2015

  Due to an increasing amount of music being made available in digital form in the Internet, an automatic organization of music is sought. The paper presents an approach to graphical representation of mood of songs based on Self-Organizing Maps. Parameters describing mood of music are proposed and calculated and then analyzed employing correlation with mood dimensions based on the Multidimensional Scaling. A map is created in which...

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• In Memoriam Professor Jerzy KAPELEWSKI

  Publikacja

  • E. Kozaczka

  - Archives of Acoustics - Rok 2015

  Professor Jerzy Kapelewski In Memoriam

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• Impact of Microphytobenthos Photosynthesis on the Characteristics of the Echo Signal from Baltic Sandy Sediments

  Publikacja

  • N. Gorska
  • E. Kowalska-Duda
  • J. Marszal
  • J. Schmidt
  • Z. Klusek

  - Archives of Acoustics - Rok 2015

  The understanding the influence of biological processes on the characteristics of the signals backscattered by the sea floor is crucial in the development of the hydroacoustical benthic habitat classification techniques. The impact of the microphytobenthos photosynthesis on the acoustical backscattering properties of the Atlantic sandy sediments was previously demonstrated by Holliday et al. (2004) and Wildman and Huettel (2012). To...

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• "Creating a numerical model of noise conditions based on the analysis of traffic volume changes in cities with low and medium structure.

  Publikacja

  • K. Marciniuk
  • B. Kostek

  - Archives of Acoustics - Rok 2015

  The subject of this research study is to analyze noise conditions of the selected area in the city of Gdańsk using data related to traffic volume changes during a day. This is because daily distribution of noise levels is much more helpful for noise control and reduction than traditional maps with Lden levels indicated. Calculations are made with the use of a numerical model developed at the Gdansk Univ. of Technology and implemented...

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Rok 2014

• Variable Ratio Sample Rate Conversion Based on Fractional Delay Filter

  Publikacja

  • M. Blok
  • P. Drózda

  - Archives of Acoustics - Rok 2014

  In this paper a sample rate conversion algorithm which allows for continuously changing resampling ratio has been presented. The proposed implementation is based on a variable fractional delay filter which is implemented by means of a Farrow structure. Coefficients of this structure are computed on the basis of fractional delay filters which are designed using the offset window method. The proposed approach allows us to freely...

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• Underwater Acoustic Imaging of the Sea

  Publikacja

  • G. Grelowska
  • E. Kozaczka

  - Archives of Acoustics - Rok 2014

  Acoustic waves are a carrier of information mainly in environments where the use of other types of waves, for example electromagnetic waves, is limited. The term acoustical imaging is widely used in the ultrasonic engineering to imaging areas in which the acoustic waves propagate. In particular, ultrasound is widely used in the visualization of human organs - ultrasonography (Nowicki, 2010). Expanding the concept, acoustical imaging...

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• Standing Waves and Acoustic Heating (or Cooling) in Resonators Filled with Chemically Reacting Gas

  Publikacja

  • A. Perelomova
  • W. Pelc-Garska

  - Archives of Acoustics - Rok 2014

  Standing waves and acoustic heating in a one-dimensional resonator filled with chemically reacting gas, is the subject of investigation. The chemical reaction of A ! B type, which takes place in a gas, may be reversible or not. Governing equations for the sound and entropy mode which is generated in the field of sound are derived by use of a special mathematical method. Under some conditions, sound waves propagating in opposite...

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• Experiments and FE analyses on airborne sound properties of composite structural insulated panels

  Publikacja

  • A. Wawrzynowicz
  • M. Krzaczek
  • J. Tejchman

  - Archives of Acoustics - Rok 2014

  Artykuł przedstawia wyniki doświadczalne i numeryczne odnośnie właściwości akustycznych paneli budowlanych. Jako panele zastosowano płyty kompozytowe konstrukcyjno-izolacyjne CSIP. Obliczenia numeryczne wykonano MES stosując podejście zaproponowane w pakiecie ABAQUS. Wyniki MES porównano bezpośrednio z doświadczeniami. Zaproponowano różne spsoby poprawy właściwości akustycznych paneli.

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• Experimental Study of Silent Sonar

  Publikacja

  • J. Marszal

  - Archives of Acoustics - Rok 2014

  Stealth is a frequent requirement in military applications and involves the use of devices whose signals are difficult to intercept or identify by the enemy. The silent sonar concept was studied and developed at the Department of Marine Electronic Systems of the Gdansk University of Technology. The work included a detailed theoretical analysis, computer simulations and some experimental research. The results of the theoretical...

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• Detection Range of Intercept Sonar for CWFM Signals

  Publikacja

  • J. Marszal
  • R. Salamon

  - Archives of Acoustics - Rok 2014

  Stealth in military sonars applications may be ensured through the use of low power signals making them difficult to intercept by the enemy. In recent years, silent sonar design has been investigated by the Department of Marine Electronic Systems of the Gdansk University of Technology. This article provides an analysis of how an intercept sonar operated by the enemy can detect silent sonar signals. To that end a theoretical intercept...

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