Acoustical Physics最新文献

The acousto-optic characteristics of a paratellurite crystal with a cut angle of α = 10.2° have been investigated theoretically and experimentally. The crystal is used in an acousto-optic filter for processing optical images in visible and infrared light. The electric range of filter tuning has been experimentally determined based on the frequency dependence of the power absorbed by the piezoelectric transducer of the filter. Estimates of the range of filter tuning with respect to optical wavelengths are made. At light wavelengths of λ = 1.15 µm and λ = 0.63 µm, the dependences of the Bragg angle of incidence on the ultrasound frequency are calculated. When measuring the diffraction efficiency in the deflector operation mode, it was found that the range of filter tuning in optical wavelengths turns out to be different from that predicted as a result of measuring the electrical characteristics of the transducer and becomes narrower.

The normal mode method is widely employed for addressing depth-dependent acoustic wave propagation, with its accuracy contingent upon the precision of the propagating wavenumbers and depth mode shapes. Typically, finite-difference and finite-element methods are utilized for such solutions. Recently, a new approach has been proposed for heterogeneous depth-dependent waveguides, utilizing the classical Rayleigh–Ritz (RR) method. This method demonstrates high accuracy from low-frequency to high-frequency ranges. However, the matrices involved for solving the eigenvalue problems necessitate numerical integrations for evaluating each element, resulting in increased computational costs. To mitigate this, a similar method (RRF) is proposed, where sound speed profiles are expressed as a sum of Fourier series. This allows for the analytical computation of each entry of the RR matrices but compromises the accuracy of the wavenumbers. This paper presents a novel technique aimed at enhancing the precision of determining wavenumbers and mode shapes, while simultaneously minimizing the computational effort without compromising the accuracy. The method involves discretizing sound speed profiles using piecewise linear functions and deriving closed-form solutions for RR matrix elements, while also accounting for sound speed attenuation. Various examples are examined to evaluate the proposed method, demonstrating its capability to compute propagating radial wavenumbers with significantly improved accuracy and reduced computational cost, often achieving improvements of one or two orders of magnitude. Additionally, comparisons of transmission losses at fixed depth indicate accuracy comparable to existing solutions, without any noticeable visual discrepancies.

The aim of the study is to determine individual features of adult speech in different emotional states. The acoustic speech characteristics of 12 adult native Russian speakers were studied. The speech of informants uttering meaningless phrase in different emotional states was audio recorded: joy, anger, sadness, fear, and neutral. The temporal and spectral characteristics of speech were analyzed in the Cool Edit Pro sound editor. The maximum pitch range in male speech is revealed in phrases uttered in a neutral state and a state of joy; the minimum, in a state of sadness. For female speech, the maximum pitch range is in a state of joy and in a state of anger; the minimum, in a state of sadness and in a neutral state. The pitch range in female speech is larger than that in male speech. For seven informants, it was shown that the duration of utterances in a state of sadness was longer compared to other states, and in a state of joy, on the contrary, it was minimal. Both male and female utterances in a state of joy were characterized by maximum pitch range values; conversely, in a state of sadness, by minmum values. Pauses between words in utterances in a state of sadness were detected in both men and women. Thus, differences in the temporal and spectral characteristics of utterances in different emotional states are revealed. The individual features of the manifestation of the emotional state in the speech of adults are determined.

Aiming at the consensus problem of slow convergence for the active noise control (ANC) model based on standard FxLMS algorithm that leads to performance degradation, this paper takes the error signal and its variation as the inputs of fuzzy logic control, and proposes an improved FxLMS algorithm by fuzzy control mechanism with two-input-two-output TSK fuzzy rules (TSK-FxLMS); In addition, the four-channel ANC models based on standard FxLMS and TSK-FxLMS are constructed using the noise signals from four measuring points inside an electric bus under uniform and variable speed conditions, respectively. Ultimately, the offline simulation and acoustic parameter calculation results indicate that the A-weighted sound pressure level (ASPL) and loudness of the two FxLMS models within the low and middle frequencies are significantly reduced, whereas the TSK-FxLMS model has faster convergence rate, higher average reduction percentage of ASPL and loudness, which proves that the established four-channel TSK-FxLMS model has a better sound quality improvement effect than the standard FxLMS.

In order to break through the diffraction limit of traditional sound sources, an idea of far-field super-resolution imaging based on acoustic superlens is proposed, that is, acoustic super-lens is used to transmit near-field sound field information to the far-field, and far-field super-resolution imaging is realized by combining phase conjugate algorithm. In this paper, the sound source localization effect of the two-dimensional honeycomb acoustic superlens of water/mercury material is systematically studied, and the sub-wavelength imaging with a resolution of 0.22λ is obtained by simulating the point sound source imaging through numerical simulation, and the imaging principle of the refractive index n = –1 configuration is explained by combining the imaging principle of flat lens imaging and the law of refraction. A multi-lens was designed for far-field localization of point sound sources, and sub-wavelength imaging with a resolution of 0.19 λ was obtained.