Naserabadi M.J.Ranjbar, Sodagar S. «Ultrasonic high frequency lamb waves for evaluation of plate structures» Акустический журнал, 63, № 4, с. pp. 402-409 (2017)

The potentials of high frequency Lamb wave modes are investigated in the inspection of plate-like structures. The wave propagation characteristics of higher order wave modes and the corresponding sensitivity and detectability are studied. Finite element simulations are carried out using infinite elements to model the ultrasonic wedge transducer and the inspection system. Experimental pulse–echo measurements are conducted to verify the influence of different modes characteristics predicted from the finite element simulations. The experimental measurements show a good agreement with the obtained numerical results for the fundamental modes, S₀ and A₀, and the higher order modes, S₁ and A₁, at 4 MHz mm of frequency–thickness.

Milekhina O.N., Nechaev D.I., Supin A.Ya. «Frequency Range of Compression for Discrimination of Acoustic Signals with Complex Spectra» Акустический журнал, 65, № 1, с. pp. 96-102 (2019)

Psychophysical experiments on listeners with normal hearing were conducted to discriminate the rippled spectra of an acoustic signal against maskers with different positions of the spectral band relative to the signal band. As the signal level changed from 50 to 80 dB SPL, the on-frequency masker level changed by 29 dB, whereas the low-frequency masker level (the position of the center of the spectral band was from –1.25 to –1 octave relative to the signal) changed by 8.7–9.8 dB. These results are interpreted as 0.3 dB/dB compression of responses to the signal and no compression of the effect of low-frequency maskers. If the spectral bands of the signal and masker partially overlap, discrimination of the spectral structure occurs predominantly in the part of the spectrum that does not overlap the masker spectrum and is subjected to low-frequency masking that is not compressed.

Zakhidov E.A., Kokhkharov A.M., Kuvondikov V.O., Nematov Sh.K., Tazhibaev I.I. «A Low-Frequency Photoacoustic Spectrometer with an RGB Light-Emitting Diode for Evaluating Photosynthetic Activity in Plant Leaves» Акустический журнал, 65, № 1, с. pp. 90-95 (2019)

A photoacoustic spectrometer based on a three-colored light-emitting diode (with peak emission wavelengths of 465, 525, and 640 nm) designed to determine the intensity of photosynthesis in different deep layers of plant leaves is described. The physical properties of the photoacoustic signal were studied at different wavelengths and light modulation frequencies. It was shown that the proposed spectrometer can be employed for quantitative evaluation of heat dissipation and photochemical assimilation of the absorbed light energy in this medium.