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Wyniki wyszukiwania dla: FREQUENCY DIELECTRIC SPECTROSCOPY
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Generalized Chebyshev Bandpass Filters With Frequency-Dependent Couplings Based on Stubs
PublikacjaThis paper presents an accurate synthesis method for inline and cross-coupled generalized Chebyshev bandpass filters with frequency-dependent couplings implemented via open and short stubs. The technique involves the synthesis of a lumped-element prototy pe in the form of a coupling matrix with a frequency-dependent term and the conversion of this prototype to a distributed-element mode l composed of sections of TEM lines. This...
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Time-frequency analysis of acoustic signals using concentrated spectrogram
PublikacjaThe paper presents improved method of time-frequency (TF) analysis of discrete-time signals. The method involves signal's local group delay (LGD) and channelized instantaneous frequency (CIF) to purposely redistribute all Short-time Fourier transform (STFT) lines. Additionally, the energy concentration index (ECI) and some histogram-like statistics are used to evaluate readability of estimated TF distributions of the energy. Recorded...
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Electrochemical Evaluation of Sustainable Corrosion Inhibitors via Dynamic Electrochemical Impedance Spectroscopy
PublikacjaFinding suitable measurement methods for the effective management of electrochemical problems is of paramount importance, particularly for improving efficiency in corrosion protection. The need for accurate measurement techniques specific to nonstationary conditions has long been recognized, and promising approaches have emerged. This chapter introduces dynamic electrochemical impedance spectroscopy as a novel advancement in electrochemistry...
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Excited states of isoxazole molecules studied by electron energy-loss spectroscopy
PublikacjaElectron energy-loss spectra were measured in isoxazole in the excitation energy range 3.5−10 eV to investigate the valence excited states. Spectra recorded at different scattering conditions enabled the identification of the singlet and triplet states and the determination of their vertical excitation energies. The two lowest energy triplet bands, ππ* 13A' and ππ* 23A' at 4.20 and 5.30 eV, respectively show vibrational progressions....
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Evaluation of the fast impedance spectroscopy method in the laboratory measurement system
PublikacjaIn this paper the method for fast impedancespectroscopy of technical objects with very high impedance(|Zx| ≥ 1 GΩ) is evaluated by means of simulation and practicalexperiment. The method is based on excitation of an object, witha square pulse and measurements of voltage and currentresponses with DAQ card. The object impedance spectrum isobtained with use of continuous Fourier transform. Someimprovements of the method concerned...
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Determination of Hydroxy Groups in the Modified Epoxy Oligomers Using IR-Spectroscopy
PublikacjaThe use of IR-spectroscopy has been proposed to determine the content of hydroxy groups in the modified functional oligomers based on bisphenol A diglycidyl ether. Apart from hydroxy groups the investigated oligomers contain epoxy or peroxy, carboxy or acrylic groups.
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High frequency oscillations are associated with cognitive processing in human recognition memory
PublikacjaHigh frequency oscillations are associated with normal brain function, but also increasingly recognized as potential biomarkers of the epileptogenic brain. Their role in human cognition has been predominantly studied in classical gamma frequencies (30-100 Hz), which reflect neuronal network coordination involved in attention, learning and memory. Invasive brain recordings in animals and humans demonstrate that physiological oscillations...
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Investigation of H2:CH4 plasma composition by means of spatially resolved optical spectroscopy
PublikacjaThe system based on spatially resolved optical emission spectroscopy dedicated for in situ diagnostics of plasma assisted CVD processes is presented in this paper. Measurement system coupled with chemical vapour deposition chamber by dedicated fiber-optic paths enables investigation of spatial distribution of species densities (Hx, H+, CH, CH+) during chemical vapour deposition process. Experiments were performed for a various...
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Hysteresis modelling of a medium frequency single-phase transformer
PublikacjaThe article describes a feedback Preisach hysteresis model equivalent circuit implementation of a medium frequency single-phase transformer being a part of a high power and high efficiency DC-DC converter. The macroscopic models of magnetic hysteresis are introduced and the feedback Preisach model is selected for further analysis. The hysteresis model is developed for a prototype transformer and the hysteresis loops are compared...
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A fast time-frequency multi-window analysis using a tuning directional kernel
PublikacjaIn this paper, a novel approach for time-frequency analysis and detection, based on the chirplet transform and dedicated to non-stationary as well as multi-component signals, is presented. Its main purpose is the estimation of spectral energy, instantaneous frequency (IF), spectral delay (SD), and chirp rate (CR) with a high time-frequency resolution (separation ability) achieved by adaptive fitting of the transform kernel. We...
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A Compact Basis for Reliable Fast Frequency Sweep via the Reduced-Basis Method
PublikacjaA reliable reduced-order model (ROM) for fast frequency sweep in time-harmonic Maxwell’s equations by means of the reduced-basis method is detailed. Taking frequency as a parameter, the electromagnetic field in microwave circuits does not arbitrarily vary as frequency changes, but evolves on a very low-dimensional manifold. Approximating this low-dimensional manifold by a low dimension subspace, namely, reduced-basis space, gives...
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Tripping of F-type RCDs for High-Frequency Residual Currents
PublikacjaResidual current devices (RCDs) are apparatus commonly used for protection against electric shock in low-voltage electrical installations. They protect people in the case of an earth fault or even in the case of direct contact with the live parts. However, to be effective protective devices, RCDs have to detect residual currents of various waveform shapes which appear in modern electrical installations. For this purpose, RCDs...
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Tripping of F-type RCDs for high-frequency residual currents
PublikacjaResidual current devices (RCDs) are apparatus commonly used for protection against electric shock in low-voltage electrical installations. They protect people in the case of an earth fault or even in the case of direct contact with the live parts. However, to be effective protective devices, RCDs have to detect residual currents of various waveform shapes which appear in modern electrical installations. For this purpose, RCDs are...
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High Frequency Harmonics Emission of Modern Power Electronic AC-DC Converters
PublikacjaModern AC/DC converters with bidirectional power flow employing PWM boost topology generate harmonic distortions of input current in relatively high frequency range tightly related to modulation carrier frequency. These frequencies and its multiples in typical applications are usually located in frequency range from single up to several of kHz. Increased harmonic emission in this frequency range can easily and harmfully influence...
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Throughput-Coverage Characteristics for Soft and Partial Frequency Reuse in the LTE Downlink
PublikacjaThe paper presents results of simulation and evaluation of throughput-coverage characteristics for the OFDMA-based LTE network with Soft Frequency Reuse or Partial Frequency Reuse. Firstly, simulation results of throughput characteristics for a single user connection are presented, which allow the evaluation of the stability and availability of bit rate achieved in different areas of a cell. Secondly, the capacity characteristics...
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Accurate design of pseudoelliptic inline SIW filters with frequency-dependent couplings
PublikacjaThis paper presents an accurate synthesis method for inline SIW (Substrate Integrated Waveguide) generalized Chebyshev bandpass filters with frequency-dependent couplings. The technique is based on the synthesis of a coupling matrix that takes into account the impedance of the frequency-dependent stub. Thus, a loading effect compensation in adjacent resonators (via resonant frequency adjustment) and coupling elements (via coupling-value...
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A Linear Phase Filter in Quadruplet Topology With Frequency-Dependent Couplings
PublikacjaThis letter presents a design of a linear phase microwave bandpass filter. The filter is composed of four resonators arranged in the quadruplet topology. Making the cross and one direct coupling dispersive gives additional design flexibility. The first advantage of using frequency-dependent couplings is the possibility to chose an arbitrary location of a pair of complex transmission zeros (TZs) in the s-domain. The second one is...
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Speech formant frequency and pitch estimation using instantaneous complex frequency
PublikacjaW pracy opisany został algorytm estymacji częstotliwości podstawowej oraz częstotliwości środkowych i pasm formantów mowy z wykorzystaniem zespolonej pulsacji chwilowej. W artykule przedstawiono również wyniki działania algorytmu dla polskich samogłosek.
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Determination of Mathematical Model Parameters of a Medium Frequency Transformer
PublikacjaThe paper presents the results of experimental studies of the medium frequency transformer. The object of the research was a prototype of a single-phase transformer with a core made of ferrite I-core elements and windings made of Litz conductors. The research was carried out to determine the parameters of the transformer's mathematical model. The scope of the tests included determining the magnetic hysteresis loop and measuring...
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Bearing estimation using double frequency reassignment for a linear passive array
PublikacjaThe paper demonstrates the use of frequency reassignment for bearing estimation. For this task, signals derived from a linear equispaced passive array are used. The presented method makes use of Fourier transformation based spatial spectrum estimation. It is further developed through the application of two-dimensional reassignment, which leads to obtaining highly concentrated energy distributions in the joint frequency-angle domain...
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Coupled nonlinear Schrödinger equations in optic fibers theory
PublikacjaIn this paper a detailed derivation and numerical solutions of CoupledNonlinear Schr¨odinger Equations for pulses of polarized electromagnetic wavesin cylindrical fibers has been reviewed. Our recent work has been compared withsome previous ones and the advantage of our new approach over other methods hasbeen assessed. The novelty of our approach lies is an attempt to proceed withoutloss of information within the frame of basic...
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Rapid Design of 3D Reflectarray Antennas by Inverse Surrogate Modeling and Regularization
PublikacjaReflectarrays (RAs) exhibit important advantages over conventional antenna arrays, especially in terms of realizing pencil-beam patterns without the employment of the feeding networks. Unfortunately, microstrip RA implementations feature narrow bandwidths, and are severely affected by losses. A considerably improved performance can be achieved for RAs involving grounded dielectric layers, which are also easy to manufacture using...
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Low frequency nois of supecapacitor
Dane BadawczeDataset contains results of low frequency noise observation during discharge of commercially available supercapacitor, type DRL 2.7V 10F, with a nominal capacitance 10 F and a nominal voltage 2.7 V. Supercapacitor was charged to various voltages and discharged through a resistor. In the experiment the 50 Ohm and 200 Ohm resistors were used. The supercapacitor...
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Generalized adaptive notch filters with frequency debiasing for tracking of polynomial phase systems
PublikacjaGeneralized adaptive notch filters are used for identification/tracking of quasi-periodically varying dynamic systems and can be considered an extension, to the system case, of classical adaptive notch filters. For general patterns of frequency variation the generalized adaptive notch filtering algorithms yield biased frequency estimates. We show that when system frequencies change slowly in a smooth way, the estimation bias can...
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A Self-Equalized Waveguide Filter With Frequency-Dependent (Resonant) Couplings
PublikacjaThis letter presents a design of a fifth-order linear phase filter with frequency-dependent couplings. The filter is composed of a triplet that is directly coupled to two resonators at the input and output. To provide group delay flattening a cross-coupling in the trisection has a strongly dispersive character with a negative slope parameter. To achieve this, an E-plane stub with a septum was used. To further improve the filter...
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Frequency-Based Regularization for Improved Reliability Optimization of Antenna Structures
PublikacjaThe paper proposes a modified formulation of antenna parameter tuning problem. The main ingredient of the presented approach is a frequency-based regularization. It allows for smoothening the functional landscape of the assumed cost function, defined to encode the prescribed design specifications. The regularization is implemented as a special penalty term complementing the primary objective and enforcing the alignment of the antenna...
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TIME- AND FREQUENCY-DOMAIN QUASI-2D SMALL-SIGNAL MOSFET MODELS
PublikacjaA novel approach to small-signal MOSFET modeling is presented in this book. As a result, time- and frequency-domain physics-based quasi-2D NQS four-terminal small-signal MOSFET models are proposed. The time-domain model provides the background to a novel DIBL-included quasi‑2D NQS four-terminal frequency-domain small-signal MOSFET model. Parameters and electrical quantities of the frequency-domain model are described by explicit...
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Fast surrogate-assisted frequency scaling of planar antennas with circular polarisation
PublikacjaIn this work, the problem of computationally efficient frequency scaling (re-design) of circular polarisation antennas is addressed using surrogate-assisted techniques. The task is challenging and requires the identification of the optimum geometry parameters to enable the operation of the re-designed structure at a selected (required) centre frequency. This involves handling several performance figures such as the antenna gain,...
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Low frequency nois of supecapacitor
Dane BadawczeDataset contains noise measurement results on prototype electrochemical double layer capacitor. The measurement procedure is described in https://dx.doi.org/10.1515/mms-2017-0059.
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Frequency response spectra applied to assess efficiency of the training techniques
PublikacjaThe purpose of the research is to assess the increase of the muscle strength and power. Movement of the human body when the moving one impacts a stationary or moving body is taken under consideration. The waveform produced by an impact is transformed into frequency domain. The acceleration record is transformed as a complex spectrum, by the use of a Discrete Fourier Transformation. In this paper the applications of the discrete...
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Shipping Low Frequency Noise and Its Propagation in Shallow Water
PublikacjaOne of the most significant factor influencing acoustical climate of the sea is underwater noise generated by moving ships. If the considered sea area has features of the shallow water, namely the wave frequency fulfils relation f < 10c/h, where c denotes phase speed of sound, and h is depths of the sea, then in certain distance from the wave source specific image of sound pressure distribution in the mean of wave modes appears....
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Improvement of Fingerprinting Method based on Hill Cipher by using Frequency Domain
PublikacjaThe main goal of this paper is to present the advantages of a digital fingerprinting in a frequency domain over a pixel domain, in case of VoD services (Video on Demand). The paper presents basic issues of a multimedia data protection by digital fingerprinting. It also describes threats to embedded fingerprints from both collusion attacks and from a transmission itself. Possible solution was presented on the example of the DCT...
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Identification of quasi-periodically varying systems with quasi-linear frequency changes
PublikacjaThe problem of identification of linear quasi-periodically varying systems is considered. This problem can be solved using generalized adaptive notch filtering (GANF) algorithms. It is shown that accuracy of system parameter estimation can be increased if the results obtained from GANF are further processed using a cascade of appropriately designed filters. The resulting generalized adaptive notch smoothing (GANS) algorithms can...
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Periodic Properties of 1D FE Discrete Models in High Frequency Dynamics
PublikacjaFinite element discrete models of various engineering 1D structures may be considered as structures of certain periodic characteristics. The source of this periodicity comes from the discontinuity of stress/strain field between the elements. This behaviour remains unnoticeable, when low frequency dynamics of these structures is investigated. At high frequency regimes, however, its influence may be strong enough to dominate calculated...
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X-ray Photoelectron Spectroscopy of Carboxylic Acids as Corrosion Inhibitors of Aluminium Alloys
PublikacjaThe datasets, titled X-ray Photoelectron Spectroscopy studies of citric acid adsorption on aluminium alloy 5754 in alkaline media and X-ray Photoelectron Spectroscopy studies of various carboxylic acids adsorption on aluminium alloys in alkaline media, contain XPS studies of the corrosion inhibitory action of selected dicarboxylic acids towards commercially available aluminium alloy 5754 in alkaline media at pH=11. These datasets...
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Characterization of nano-silica vegetable grease with diffusing wave spectroscopy DWS and Raman spectroscopy
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Electromagnetic properties of a dielectric slab with an embedded silver nanowire grating
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Scattering of the plane wave from a periodically perforated dielectric slab
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Electromagnetic characterization of a silver nanowire grating embedded into a dielectric slab
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Oblique Plane Wave Scattering by an Array of Dielectric and Metamaterial Cylinders.
PublikacjaBadanie wpływu ujemnej przenikalności elektrycznej i magnetycznej na parametry rozproszenia fali elektromagnetycznej dla cylindrów wykonanych z dielektryka i metamateriału. Wykorzystanie zmodyfikowanej procedury iteracyjnej i metody dopasowania rodzajów do analizy ukośnego padania fali elektromagnetycznej na zbiór równoległych cylindrów.
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Rigorous Modal Analysis of Structures Containing Inhomogeneous Dielectric Cylinders.
PublikacjaW pracy wykorzystano zmodyfikowaną procedurę iteracyjną i metodę dopasowania rodzajów w celu analizy struktur zawierających asymetrycznie umieszczone, niepełnej wysokości lub wielowarstwowe, niejednorodne, cylindryczne rezonatory dielektryczne. Analiza bazuje na nowatorskiej koncepcji zwanej hybrydową macierzą impedancyjną (HIM - hybryd impedancje matrix), która opisuje relacje pomiędzy całkowitym polem elektrycznym i magnetycznym...
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Theory of scattering by an array of lossy dielectric, ferrite and conducting cylinders.
PublikacjaOpisano metodę analizy umożliwiającą określenie zastępczego pola rozproszonego od dowolnej konfiguracji prętów dielektrycznych, ferrytowych lub metalowych na zewnętrznym obszarze cylindrycznym w celu połączenia go z wybranym pobudzeniem i znalezienia macierzy rozproszenia układu. Prezentowane podejście znajduje zastosowanie w analizie struktur zamkniętych i określanie macierzy rozpraszania złączy falowodowych jak i otwartych...
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Scattering by an array of conducting, lossy dielectric, ferrite and pseudochiral cylinders.
PublikacjaOpisano metodę analizy rozpraszania fali elektromagnetycznej w systemach zawierających cylindryczne pręty dielektryczne, metalowe, ferytowe i pseudochiralne i wykorzystanie w/w metody w problemach zamkniętych i znajdowanie macierzy rozpraszania wieloportowych złączy falowodowych oraz w problemach otwartych i badanie charakterystyk rozpraszania zarówno w strefie dalekiej jaki bliskiej.
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Fast numerical analysis of dielectric resonators with perturbed rotational symmetry
PublikacjaW artykule zaprezentowano metody szybkiej analizy rezonatorow o symetrii zblizonej do osiowej metodą różnic skończonych w dziedzinie częstotliwości. Dzięki użyciu techniki rozwinęć funkcyjnych w jednorodnych obszarach uzyskano redukcję rozmiaru i znaczne przyspieszenie zbieżności problemu własnego, reprezentującegowspomniane układy. Dzięki elastycznemu sposobowi łączenia dziedzin z i bez rozwinięć funkcyjnych możliwe było zaadaptowanie...
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IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
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DETERMINATION OF SP3 FRACTION IN ta-C COATING USING XPS AND RAMAN SPECTROSCOPY
PublikacjaThe paper presents results of studies on the structure of tetrahedral amorphous carbon films (ta-C) with a thickness in the range from 20 to 280 nm, deposited using pulsed vacuum arc technique with an electromagnetic Venetian blind plasma filter. The results of the phase structure analysis, obtained using visible Raman spectroscopy and UV Raman spectroscopy methods, showed a strong dependence of the results on the presence, on...
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Non-invasive blood glucose monitoring with Raman spectroscopy: prospects for device miniaturization
PublikacjaThe number of patients with diabetes has reached over 350 million, and still continues to increase. The need for regular blood glucose monitoring sparks the interest in the development of modern detection technologies. One of those methods, which allows for noninvasive measurements, is Raman spectroscopy. The ability of infrared light to penetrate deep into tissues allows for obtaining measurements through the skin without its...
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Influence of a Radio Frequency on RF Fingerprinting Accuracy Based on Ray Tracing Simulation
PublikacjaIn this paper the influence of a radio signal frequency on performance of Indoor Positioning System based on fingerprinting has been examined using ray-tracing simulations. It has been simulated how spatial distribution of an RF signal strength change with the signal’s frequency. The results were used to show its’ impact on the behavior of localization algorithms that are employing RSS measurements to determine node’s position...
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Investigation of the electrochemical behaviour of AA1050 aluminium alloy in aqueous alkaline solutions using Dynamic Electrochemical Impedance Spectroscopy
PublikacjaThe paper presents the electrochemical behaviour of aluminium alloy AA1050 in aqueous alkaline media in the pH range 14–8.5. Electrochemical study was applied in order to obtain comprehensive information on the mechanism and kinetics of the process of anodic dissolution of aluminium, supplemented by monitoring of surface topography using an electron microscope. The corrosion rate of AA1050 increases with increasing concentration...
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Audio codec employing frequency-derived tonality measure
PublikacjaA transform codec employing efficient algorithm for detection of spectral tonal components is presented. The tonality measure used in MPEG psychoacoustic model is replaced with the method providing adequate tonality estimates even if the tonal components are deeply frequency modulated. The reliability of hearing threshold estimated using psychoacoustic model with standardized tonality measure and the proposed one is investigated...