Study On Echo Modeling And Signal Processing For Blind People With Echolocation

For each of us,echolocation is an innate ability.The study of echolocation can give us a better understanding of the process of human cognition of the surrounding environment.At the same time,by studying echolocation,we can also understand how the human auditory system processes the sound signals,which is very beneficial to our lives.On the one hand,we can improve our current audio equipment according to the processing of human echo signals,so that we can hear more realistic vocals.At the same time,some blind navigation devices can also be made for the blind.On the other hand,this signal processing method can also be introduced into the field of radar signal processing and sonar signal processing.In this thesis,the characteristics of three typical click sound signals are introduced,and an echo model is established according to the propagation and scattering rules of sound.Then the multi-angle method is used to collect the target echo signal.The method of sound incidence on the target surface is divided into two cases:vertical incidence and non-vertical incidence.Finally,different methods are used to extract the characteristic values of the echo signal,and these characteristic values are used to analyze the shape and rotation direction of the target.The main work of this thesis is summarized as follows:1)The research analyzes the time-frequency domain characteristics of the three click signals and experimentally measures their distribution in space,which provides spatial distribution data of sound waves for subsequent simulations.Secondly,the process of sound propagation in space and the echo signal generated when it meets the target is introduced and analyzed,and echo modeling is carried out according to these processes.Finally,the established echo model is used for simulation experiments,which proves that the established echo model is reliable and effective.2)The application of Mel-Frequency Cepstral Coefficients in sound is introduced,and the characteristics of echo signals of different targets are analyzed using Mel-Frequency Cepstral Coefficients under single viewing angle.The peak value of the Mel-Frequency Cepstral Coefficients is extracted as the characteristic value of the echo signal,and the shape and rotation direction of the target are analyzed under the conditions of multiple viewing angles.Then the total energy and average frequency of the echo signal are extracted,and the shape and rotation direction of the target are analyzed by using these two characteristic values.3)The model of human auditory system was built according to the characteristics of human auditory system.The echo signal was input into the auditory model to extract the corresponding SACF peak characteristic value and neuron emission rate characteristic value,and then the target imaging and rotation direction could be judged based on these characteristic values.