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Objective: There are both objective and subjective tests for evaluating the speech intelligibility. Speech Intelligibility Index (SII) and Modified Rhyme Test (MRT) are the most common methods for objective and subjective tests, respectively. While objective tests do not depend on the language, subjective tests are applied to the hearing-impaired subjects in their language. In these tests, hearing-impaired subjects try to recognize the sound by looking at the word lists in their hand. The word lists can be presented as two-word or six-word choices in design. However, the preferred type a is six-word choice for MRT. Up to now, these word lists were developed in different languages with different methods. For Turkish language, only two-word choice lists were developed; there was no study related to the Turkish language with six-word choice. In this study, we aimed to develop applicable six-word Turkish MRT lists by using hearing-impaired subjects. Methods: In this study, three different six-word Turkish MRT lists were developed according to the phonetic characteristics of the Turkish language, and these lists were tested via 12 hearing-impaired subjects. In the lists, 5 different Turkish phonetic characteristics were taken into account. For the analysis, the detailed audiograms (18 octave band) of hearing-impaired subjects were used. Results: Detailed statistical analysis for phonetic variations were shown for each hearing-impaired subject. Having correct structure and robust word choices for MRT lists were shown by comparing the equivalent speech spectrum levels of sounds and MRT results of the hearing-impaired subjects. Conclusion: New Turkish MRT lists were developed according to the phonetic characteristics of the Turkish language. Usability of the lists was shown by audiological test with the hearing-impaired subjects. Statistical analysis and the results of tests showed that developed Turkish MRT lists can be used in audiological studies as a reference material. [ABSTRACT FROM AUTHOR]

Digital waveguide mesh (DWM) models are time-domain numerical methods providing computationally simple solutions for wave propagation problems. They have been used in various acoustical modeling and audio synthesis applications including synthesis of musical instrument sounds and speech, and modeling of room acoustics. A successful model of room acoustics should be able to account for source and receiver directivity. Methods for the simulation of directional sources in DWM models were previously proposed. This paper presents a method for the simulation of directional microphones in DWM-based models of room acoustics. The method is based on the directional weighting of the microphone response according to the instantaneous direction of incidence at a given point. The direction of incidence is obtained from instantaneous intensity that is calculated from local pressure values in the DWM model. The calculation of instantaneous intensity in DWM meshes and the directional accuracies Of different mesh topologies are discussed. An intensity-based formulation for the response of a directional microphone is given. Simulation results for an actual microphone with frequency-dependent, non-ideal directivity function are presented. [ABSTRACT FROM AUTHOR]

Digital waveguide mesh (DWM) models offer a simple, accurate, time-domain, numerical solution of the wave equation. A specific case where such accurate and computationally simple solutions are needed is the acoustical modeling of open or closed volumes. It is possible to model 3-D propagation of waves in enclosures such as rooms using DWM models. Generally, idealized omnidirectional sources are used for obtaining the impulse response in the DWM. However, real-life sound sources are never completely isotropic, causing wavefronts with directional properties. This paper presents two methods to simulate analytical and empirical directivities in 3-D DWM models in the far-field. The first method is based on the direct excitation of the mesh with the velocity component of the directional source and is used to simulate analytical sources. The second method is based on the weighting of velocity components generated by an omnidirectional source at different octave-bands and is used to simulate sources with frequency-dependent empirical directivity functions. A simple interpolation method for obtaining a closed-form description of the directivity function from incomplete directivity data is also proposed. Simulation results are presented for two sources in an acoustical model of a rectangular room. [ABSTRACT FROM AUTHOR]

Various techniques have previously been proposed for the separation of convolutive mixtures. These techniques can be classified as stochastic, adaptive, and deterministic. Stochastic methods are computationally expensive since they require an iterative process for the calculation of the demixing filters based on a separation criterion that usually assumes that the source signals are statistically independent. Adaptive methods, such as the adaptive beamformers, also exploit signal properties in order to optimize a multichannel filter structure. However, these algorithms need initialization and time to converge. Deterministic methods, on the other hand, provide a closed-form solution based on the deterministic aspects of the problem, such as the channel characteristics and the source directions. This paper presents a technique that exploits the intensity vector statistics to achieve a nearly closed-form solution for the separation of the convolutive mixtures as recorded with a coincident microphone array. No assumptions are made on the signals, but it is assumed that the source directions are known a priori. Directivity functions based on von Mises functions are designed for beamforming depending on the circular statistics of the calculated intensity vectors. Numerical evaluation results were presented for various speech and instrument sounds and source positions in two reverberant rooms. [ABSTRACT FROM AUTHOR]

Digital waveguide mesh (DWM) models are numerical solvers for the wave equation in N-dimensions. They are used for obtaining the traveling-wave solution in practical acoustical modeling applications. Although unstructured meshes can be used with DWMs, regular mesh topologies are traditionally used due to their implementation simplicity. This letter discusses the accuracy of first-order approximations to numerical derivatives on more general unstructured mesh topologies. The results are applied to structured, regular mesh topologies as used in DWM modeling. A comparison of 2-D and 3-D DWM topologies with respect to the accuracy of first-order approximations to numerical derivatives is presented. [ABSTRACT FROM AUTHOR]

One of the simplest ways of designing allpass fractional-delay filters with maximally fiat group delays is by using the Thiran approximation by which the filter coefficients are calculated using a closed-form equation. However, due to the number of multiplications and divisions involved, the calculation of these coefficients is a computationally costly task and is not suitable for real-time applications. The analysis of a root-displacement-based interpolation method used in allpass tunable fractional delays is presented in this paper. The method allows continuous adjustments of the approximated fractional delay without the explicit calculation of a new set of filter coefficients. The transient error observed at the output due to the change of filter coefficients is analyzed. The direct and cascade implementations are compared with respect to their transient errors. An example application of the proposed method from the field of model-based sound synthesis is given. [ABSTRACT FROM AUTHOR]