Mathematical Model of Sound Absorption by Lungs with Acoustic Stimulation of the Respiratory System.

According to the results of theoretical and experimental analysis of the characteristics of the propagation of acoustic vibrations in the respiratory system, it is necessary to determine the resonant frequency of the respiratory tract to increase the vital capacity of the lungs by opening reserve alveoli by acoustic stimulation of the respiratory system and then to affect the respiratory system with scanning tonal sounds in the maximum sound absorption range (at a level of ±3 dB of the maximum absorption coefficient value).

Experimental study of displays in contralateral acoustic reflex auditory stimulation.

The results of an experimental study of manifestations of the acoustic reflex with contralateral auditory stimulation at a frequency of 1 kHz are presented, and the principal possibility and informativeness of its use for diagnosing the diseases of the organ of hearing are demonstrated. The principal difference of the developed approach is the use of polyharmonic signal for measuring acoustic reflex manifestations during contralateral stimulation, which allows accelerating the examination procedure.

[Occupational deafness in workers of locomotive crew and its association with risk factors].

The authors studied relationship between occupational neurosensory deafness and risk factors in locomotive crew workers. Examination covered 173 locomotive crew workers divided into 2 groups: group 1--with occupational neurosensory deafness (n = 85) and group 2--without occupational neurosensory deafness (n = 88). Study covered occupational factors and calculated effective dose connected to length of service for exposure assessment. Complex clinical and laboratory study was performed. For signs structure analysis, principal components method and chances ratio were used. Occupational neurosensory deafness appeared to be reliably connected with length of service, arterial hypertension, dyslipidemia--with OR equals 5.7 (95% CI: 2.98-11.00), 1.88 (95% CI: 1.03-3.43) and 2.79 (95% CI: 1.5-5.18) respectively. That necessitates correction of hypertension and dyslipidemia.

Mathematical justification of the acoustic method for measuring the impedance of the respiratory tract.

A new method for measuring a complex frequency-dependent acoustic impedance of the respiratory tract based on two-microphone method was developed. The measuring device consists of a waveguide connected through a mouthpiece to the patient's mouth. A sound field with a frequency range from 5 to 100 Hz is created in the waveguide. The impedance of the respiratory tract is determined at free respiration of the patient in the set frequency range; the duration of examination does not exceed 15 s. The criteria for the recognition of respiratory tract pathologies are proposed.

A new approach to the study of impedance characteristics of tympanic membrane.

A new approach to studying the tympanic membrane impedance characteristics, based on the analysis of polyharmonic acoustic signals reflected by the tympanic membrane, is described. For this purpose, the acoustic pressure and the phase difference between the acoustic vibrations in two sections of a waveguide sealingly connecting the external auditory meatus and a generator of polyharmonic audio signals is measured. By processing the results of measurements, the estimates of the frequency-dependent reflection coefficients, absorption coefficients, and components of the acoustic impedance of the tympanic membrane are calculated. The features that principally distinguish the developed approach from other approaches are the absence of the necessity to create a positive pressure in the external auditory meatus, the absence of ultrasonic radiation into the external auditory meatus and a high-intensity sound, and the possibility of direct measurement of the tympanic membrane impedance in the audio frequency range with any step.

[Evaluation of acoustic effectiveness of personnel protectors from extra-aural exposure to aviation noise].

Purpose of the investigation was to validate testing acoustic effectiveness of a personnel vest-like protector (PP) from extra-aural exposure to aviation noise. Levels of aviation noise for PP testing were determined through calculation. Vest effectiveness in protecting from acoustic vibration generated by high-intensity aviation noise was evaluated both in laboratory and field tests. For comparison analysis, PP was also tested with a dummy exposed on a special tester, i.e. acoustic interferometer.

[Impulse noise at shooting from small arms and close combat weapon as the factor of military work].

The high-intensity impulse noise which is basic source in Armed forces are the firearms, has an adverse effect on professional soldiers, leading to decrease of professional working capacity and health deterioration. Due to influence of this factor the considerable part of military men has a hearing impairment and other diseases, including an arterial hypertension. The basic directions of protection of men from impulse noise are: perfection of hygienic rationing, optimization of the using of antinoise earphones, development of new generation of means of individual defense from noise.

[Hygienic estimation of combined influence of noise and infrasound on the organism of military men].

Hygienic estimation of combined influence of noise and infrasound on the organism of military men. Combined influence of noise and infrasound is accompanied by essential increase of risk of development neurosensory deafness and hypertensive illness. At combined influence of noise and infrasound with a maximum of a spectrum in the field of a sound range the probability of development neurosensory deafness will prevail. Thus probability of development of pathology of ear above the values established ISO 1999:1990. In a case if the spectrum maximum is necessary on an infrasonic range the probability of development of a hypertensive illness.