Study On Acoustic Sensory Evaluation Method Based On Evoked Potential

The comfort of human body is closely related to the physical environment of building.The comfort of acoustic environment is an important link in the evaluation of indoor environment,which affects people’s work efficiency,emotional changes and physical health.There is bioelectricity,or brainwaves,in the human brain.Everything in nature obeys the law of conservation of energy,and so does the electric field in the central nervous system of the brain.When the human brain is stimulated by the sound of the external environment,nerve impulses are generated inside and outside the nerve cells,and the nerve impulses form brain currents in the nerve conduction pathway.Brainstem auditory evoked potential(BAEP)is an objective indicator of neural potential activity caused by sound stimulation.Brainstem auditory evoked potential(BAEP)is a new research idea to objectively evaluate acoustic environment comfort by using this objective indicator to reflect human subjective acoustic experience.In this paper,starting from the problem of human acoustic comfort,the brainstem auditory evoked potential is taken as an objective indicator,the energy analysis method of wavelet transform is used,the subjective questionnaire survey of acoustic sensory evaluation is combined with.The acoustic sensory comfort zone based on the BAEP energy coefficient is obtained,which is used to evaluate human acoustics comfort and puts forward new research ideas and methods.Firstly,the acoustic sensation experiment was designed in the noise environment,and the subjective evaluation of the subjects’ acoustic sensation was investigated by controlling the change of the sound pressure level and frequency of background noise.At the same time,the auditory evoked potentiometer was used to test the brainstem auditory evoked EEG of the subjects,and the objective EEG data were recorded.Secondly,the latent period and amplitude of the measured brainstem auditory evoked potential were analyzed,and the mechanism of auditory conduction pathway was studied.Finally,using the wavelet transform energy analysis method,combined with the subjective survey of the comfort of acoustic environment,the mechanism of human acoustic comfort is further studied,and the comfort evaluation interval of human acoustic feeling is obtained.Based on the above research,the main conclusions of this paper are as follows:(1)While the main stimulus sound remains unchanged,the background noise pressure level and frequency have an impact on the subjective sound perception evaluation.With the increase of the background noise pressure level,the environmental loudness is enhanced,the stimulation is weakened,and the comprehensive comfort of human body is improved.When the background noise pressure level is high,the frequency increases,so that the stimulation is weakened and the comprehensive comfort level is improved.(2)While the main stimulus sound remained unchanged,the background noise pressure level and frequency had an effect on the latency and amplitude of the brainstem auditory evoked potential.With the increase of the background noise pressure level,the latency of Ⅴ wave of the evoked potential was prolonged,and the variation trend of the bar,Max and Max amplitude of the evoked potential was decreased.With the increase of the frequency of background noise,the incubation period of Ⅰ wave of the evoked potential is advanced,while the incubation period of neutral and neutral wave is prolonged,and the amplitude of non-negative wave of the evoked potential is reduced.(3)The latent period and amplitude of brainstem auditory evoked potential were changed by the subjective sound sensation of human body while the main stimulus sound remained unchanged.The increase of ambient loudness will prolong the incubation period of Ⅴ wave and decrease the amplitude of N,N and N waves.The enhancement of human stimulation will shorten the incubation period of Ⅴ wave and increase the amplitude of T,T and T wave.The improvement of the comprehensive comfort of human body will prolong the Ⅴ wave incubation period and reduce the N,H and H wave amplitudes.(4)The wavelet transform energy analysis method is used to calculate the "BAEP energy coefficient",which can objectively evaluate the acoustic comfort of human body.This processing method reflects the degree of fluctuation of the sum of postsynaptic potential of cerebral cortical neurons after auditory stimulation at a certain sound pressure level.Using this method to evaluate the degree of sound stimulation and human comfort is feasible from the perspective of auditory mechanism.(5)The change of the background noise pressure level and frequency has a significant effect on the "BAEP energy coefficient".As the background noise pressure level increases,the sound pressure level of the main sound stimulus signal in the brainstem auditory evoked potential test remains unchanged,and the SNR decreases continuously.With the reduction of SNR,the BAEP energy coefficient decreased,indicating that the energy of auditory evoked potential signals decreased,and the energy consumed by the auditory nerve in the brain decreased.The increase of the frequency of background noise will also decrease the BAEP energy coefficient,that is,the energy of auditory evoked potential signals decreases,and the energy consumed by the auditory nerve of the brain decreases.(6)Combine the background noise pressure level,"BAEP energy coefficient" and the subjective sound sensation evaluation of human body to form the evaluation range of human sound sensation comfort.According to the conservation of energy,the work done by the human brain is transformed into bioelectric energy.The more work the human brain does,the more brainpower it consumes,the stronger the brainwave generated,and the higher the energy of the corresponding auditory evoked potential.Conversely,the less work a human brain does,the less brainpower it expends,and the weaker the brainwaves it produces,and the lower the energy of the corresponding auditory evoked potential.It can be seen that the method of EEG energy analysis follows the law of human comfort and low energy consumption.