Specialized acoustic devices and sound signal parameters affecting Individual hearing and psychophysiological health

Relevance. The integration of specialized acoustic devices into law enforcement operations justifies the need for a study and biomedical assessment of the emitted sound signal characteristics and effects with regard to human body.

The objective is to examine the characteristics and impact of a specialized acoustic device on the patient’s auditory system and psychophysiology, as well as to study the characteristics and influence of the sound signal produced by a special acoustic device on the hearing ability and psychophysiological parameters.

Methods. A laboratory study was conducted to analyze a specialized audio signal. Experiments were performed with 10 volunteers at sound levels of 127 dBA with a 3-minute exposure (LEX,8h = 105 dBA) and 110 dBA with a 20-minute exposure (LEX,8h= 96.2 dBA). Self-reported measures of well-being, activity, and mood were assessed using the SAN test (the test name derived from the first letters of Russian words for well-being (S), activity (A), mood (N); anxiety was measured using the Spielberger-Khanin method. The data are presented as medians, the 25th and the 75th percentiles (Me [Q25; Q75]); pairwise comparisons were performed using the Wilcoxon signed rank test to examine differences within groups.

Results and Discussion. The study established that the analyzed sound signal was a tonal high-frequency noise, with maximum sound pressure concentrated in 1/₃-octave band center frequencies at 2500 and 3150 Hz. The sound had a complex structure, with the amplitude fluctuating over time (10 times per second) for individual sound components. Exposure to the sound signal at 127 dBA for 3 minutes resulted in increased hearing thresholds at 4 kHz (p = 0.012) and 6 kHz (p = 0.01) frequencies. However, no significant changes in the overall functional state of the volunteers were observed. Hearing thresholds and psychophysiological parameters recovered to baseline in all participants within 24 hours. Conversely, exposure to a sound signal at 110 dBA for 20 minutes had a significant impact on general well-being, causing headaches, apathy, sleep disorders. Additionally, well-being, activity and positive mood measures dropped down, along with increased situational and personal anxiety. The hearing was notably affected, showing increased auditory perception thresholds exceeding 40 dB at frequencies of 3, 4, and 6 kHz; followed by a lengthy hearing recovery in up to 5 days.

Conclusion. Considering the spectral characteristics, the sound signal should be defined as tonal high-frequency noise, with a maximum sound pressure at 1/₃-octave band frequency of 2000 and 3150 Hz. The sound exhibits pulsation, with the amplitude of particular components varying over time. The impact exerted by specialized acoustic signals should be evaluated with a focus on exposure duration, as well as the equivalent sound level. The obtained results showed pronounced impact on volunteers at lower LEX,8h.