Noise annoyance evaluation and characterization of occupational noise exposure in transformer substations

Previous evaluations of occupational noise exposure in substations are primarily based on the hearing loss hazards of noise. Non-auditory effects, such as perceived noise annoyance, also have a significant influence on the human body. It is necessary to study the characterization and evaluation method of occupational noise exposure in substations based on perceived noise annoyance. Noise samples from main transformers with different voltage levels were recorded on-site. Laboratory listening tests were conducted to analyze the noise annoyance of main transformer noise in transformer substations with different voltage levels. Furthermore, the annoyance was compared with seven types of non-substation noise. Main transformer noise has significant tonal and low-frequency characteristics, which can exacerbate noise annoyance. Under the same level of noise annoyance, the higher the voltage level, the lower the A-weighted sound pressure level; the A-weighted sound pressure level of 1000 kV substation noise is approximately 10 dB lower than that of 110 kV substation noise, and cooling fan noise may contribute to this difference. The change trend of perceived annoyance with respect to the A-weighted sound level for the seven types of non-substation noises differs significantly from that of substation noise. If noise exposure limits are determined based on perceived noise annoyance, the limits for other types of noise may not be suitable. Limits for substations of different voltage levels should vary, with higher voltage levels requiring lower limits. There is a strong correlation between psychoacoustic annoyance and perceived annoyance of substation noise, with R² reaching 0.944 when fitted by an exponential function. Psychoacoustic annoyance of substation noise can be calculated directly based on its psychoacoustic parameters. Thus, psychoacoustic annoyance can be converted into noise perception annoyance, which can be used to evaluate occupational noise exposure.