The aim of this study is to investigate the manifestation of emotional states in the speech of typically developing adolescents (TD) and adolescents with intellectual disabilities (ID); to determine the acoustic and perceptual characteristics of the emotional speech of adolescents. Emotional speech from 25 adolescents was analyzed while they read nonsense texts in the emotional states of joy, neutral, sadness, anger, and fear. Spectrographic analysis was carried out using the software Cool Edit Pro 2.0. The following parameters were measured: duration; pitch values (F0); minimum (F0min) and maximum (F0max) pitch values; pitch range values (F0max – F0min); intensity values for the phrase, stressed word, and stressed vowel. A perceptual experiment involving 10 adult listeners was conducted. Differences in acoustic characteristics of emotional speech were identified between TD and ID adolescents: word and vowel duration; minimum pitch values for words and vowels. According to the results of the perceptual experiment, TD adolescents demonstrated a better ability to express sadness and anger in their voice compared to adolescents with ID.

To optimize the sound absorption performance of aluminum foam, a dual-porosity aluminum foam consisting of different perforation configurations is proposed. A theoretical model of the structure is established using the transfer matrix method, and a simulation model is constructed with COMSOL software. The accuracy of the results is verified through sound absorption experiments. By analyzing the sound absorption mechanism and exploring the influence of structural parameters on sound absorption performance, the results indicate that front-perforation induces a pressure diffusion effect, effectively enhancing acoustic energy dissipation and improving sound absorption. By adjusting the radius of front-perforation, a balance between the pressure diffusion effect and acoustic energy dissipation in the matrix material can be achieved, thereby maximizing sound absorption performance. When the perforation radius exceeds 7.5 mm, the sound absorption performance of aluminum foam with side perforations is significantly superior to that with front perforation. The perforation diameter on the incident surface significantly influences sound absorption, resulting in similar performance between the inverted gradient perforation dual-porosity aluminum foam (IG-DPAF) and the “I-shaped gradient” perforation dual-porosity aluminum foam, both demonstrating excellent broadband sound absorption properties with absorption coefficients exceeding 0.8 across the frequency range of 1000–6300 Hz. Conversely, the sound absorption behavior of the positively gradient perforated dual-porosity aluminum foam (PG-DPAF) resembles that of the “+shaped gradient” perforation dual-porosity aluminum foam in terms of sound absorption behavior. This study provides novel insights for the structural design and performance optimization of aluminum foam-based sound-absorbing materials.

The article is devoted to determining the optimal parameters of sounding signals of a hydroacoustic system for monitoring temperature regimes of seawater areas on a thousand-kilometer scale. The results of modeling the noise immunity of complex signals of various durations and resolutions are presented. The results of modeling and full-scale tests on a 1073-km-long acoustic path in the Sea of Japan are presented. The influence of the waveguide impulse response on the noise immunity of signals with different resolutions is shown. Preferred sequences of sounding signals have been determined.

Using numerical modeling based on mode theory and the geometric-acoustic approximation, it was determined that in addition to classical quadruples of pulses present in the spatiotemporal field structure, the emergence of additional signals with relatively short delays is caused by the formation of weakly divergent multimode beams in the underwater sound channel of the Sea of Japan; these modes correspond to smooth extrema in the dependences of the spatial interference period of neighboring modes and their group velocity on the mode number. For one of the two sound speed profiles typical of the Sea of Japan, it was shown that at relatively high frequencies, it is possible to receive two groups of additional signals: weakly divergent beams formed by relatively low- and high-order modes.

The fine structure of the seismic background in the territory of an oil field was studied using polyspectral analysis and surrogate models. The statistical test for Gaussianity and linearity showed that the natural seismic background in the 1–50 Hz frequency range is a nonlinear process. Bicoherence graphs revealed statistically significant peaks of phase-coupled triplets with a characteristic geometry of peak clustering in the triangular principal domain. To analyze the quasi-noise component of the seismic background, surrogate time series with a randomized phase spectrum were generated, the bispectra of which are free of triplet peaks. Bispectral analysis of surrogate series showed the presence of a non-Gaussian quasi-noise component in the seismic background in the frequency range of 1–6 Hz. Previously, the results of the analysis of the used set of records by two completely different methods, each of which extracts information from different components of the seismic background, quasi-noise and regular, were published. These studies showed that each of the two components contains information sufficient to estimate the total thickness of the productive intervals under the recording point. Based on the results of the bispectral analysis and the features of the algorithms of the two methods, a conclusion was made that the quadratically phase-coupled triplets and the non-Gaussian quasi-noise component in the field territory are manifestations of endogenic seismic emission and are generated by the same nonlinear process developing in the vicinity of an oil-saturated reservoir. The mechanism of seismic emission should be sought in the class of phenomena with quadratic nonlinearity. The statistical characteristics of the internal structure of the seismic background near oil wells have similar features that differ greatly from the statistical characteristics of the seismic record near a “dry” well located outside the reservoir and not producing oil. Previously unknown prognostic features of the oil/water saturation type of rocks have been identified.

The current state of the problem of applying holographic interferometry in underwater acoustics is presented. The discussion of holographic signal processing is focused on solving the problem of monitoring the underwater environment, ensuring the detection, resolution, and localization of underwater noise sources under conditions of low signal-to-noise ratio and spatiotemporal perturbations in the oceanic environment. Localization of the sound source is understood as determining the bearing, radial velocity, range, and depth. Single vector–scalar receivers and linear antenna arrays are considered as the receiving modules. The results of theoretical studies, numerical modeling, and field experiments are provided, allowing for assessment of the efficiency of holographic processing under realistic conditions.

The propagation of a Rayleigh-type surface acoustic wave (SAW) along the free boundary of a layered half-space with a smooth change in its elastic parameters horizontally is considered analytically and numerically. The change in amplitude of the SAW for the transition of a wave from a single-layer system to a single-layer, single-layer to two-layer, and two-layer to two-layer system depending on the elastic parameters, as well as the length of the sounding wave, is calculated. It is shown that as it propagates, the amplitude of SAW decreases with an increase in the velocity of longitudinal waves and density of the medium, and with an increase in the velocity of transverse waves in the medium, the SAW amplitude can both increase and decrease. The change in the SAW amplitude associated with a change in the longitudinal wave velocity is stronger; therefore, this parameter should be taken into account in applied methods. It is shown that the magnitude of the dominant wavelength depends on both the geometric and elastic parameters of the system.

A comparative analysis has been performed on the morphology and some hearing mechanisms of the evolutionary new external ears of bottlenose dolphin (Tursiops truncatus) and human ears. It has been established that the role of external hearing canals in dolphins is played by corresponding mental foramens (MF), mandibular canals (MC), and soft tissues (ST) filling them. It has been demonstrated that the hearing canals of dolphins are maximally ported out to the tip of the rostrum towards echos and sounds reflected from underwater objects, in contrast to the hearing canals of humans, which are located on the left and right sides of the head. The major factors influencing the mechanisms of the formation of unique features in the spatial sound localization of dolphins are asymmetry in the architecture of their hearing canals, rostrum, and skull. However, for humans, these mechanisms are caused by the symmetric location of hearing canals on the left and right sides of the head. The morphology of the external ears of dolphins is adapted to utilize the destructive interference of reflected coherent interferences with the purpose of improving the signal/reflected interferences ratio. In general, the specific features of dolphin and human hearing cause fundamental distinctions in the morphology and auditory mechanisms of their external ears.

The article presents a study of the acoustic field of the propeller, including at the resonance frequencies of its blades. The study is based on a computational and experimental approach with the combined use of numerical and experimental physical modeling. The article shows the importance of taking into account the elastic resonances of the propeller in the design, demonstrates the methods of physical and numerical modeling used, which provide high accuracy in determining the resonance frequencies of the blades in water and in air. Using the example of two propeller models made of different materials, the effect of the Q-factor on the levels and type of radiation spectrum is experimentally demonstrated.

The article considers the possibility of using a nondestructive spectral-acoustic method for quantitative control of the porosity of Kh12MF steel samples obtained by hot isostatic pressing. The results of studies of samples obtained at different stages of hot isostatic pressing in the residual porosity range from 0 to 9% are presented. The control technique is based on the analysis of acoustic structural noise parameters. Various methods of measuring parameters of structural noise are analyzed from the point of view of sensitivity and measurement error of the used informative parameters of structural noise. Clarified calculation algorithms for determining the parameters of structural noise are proposed, and the results of their experimental verification are presented. The obtained results can serve as a basis for developing an engineering method for assessing the degree of porosity of the material of parts and structural elements obtained by hot isostatic pressing, under operating conditions.