Design And Implementation Of An Active Noise Deduction Headphone With Large Earmuffs

With the continuous improvement of the mechanization of our army,the number of tanks,armored vehicles,helicopters,and fixed wing aircraft has increased dramatically,and the high noise in these equipment has become an important problem that affects the intelligibility and hearing health of the driver's voice communication.In the civil field,the noise is rapidly developing with the industry and traffic.The impact of pollution on the lives of residents is becoming more and more serious.Therefore,the problem of noise control has been attracting more and more attention.The general noise control method is to use passive noise reduction,which is easy to realize,however,for low frequency noise of 800 Hz or lower frequency,the passive noise reduction method has almost no effect.At the same time,active noise reduction technology is the most effective way to reduce noise in the local area of the ear muff.In this paper,the application of active noise reduction technology in the noise reduction headset of large earmuff is studied,mainly from the principle and classification of active noise reduction,the characteristics of the pickup device,secondary sound source,structure and material,acoustic cavity and its influence on the noise reduction performance of the active noise reduction system,the realization of the circuit of the active noise reduction ear machine and the acoustics of active noise reduction Four aspects of the test are analyzed and studied.The active noise reduction mainly uses the interference cancellation principle of the sound wave in space to realize the noise control.According to the noise reduction system architecture,it is divided into feedforward,feedback and compound,and the circuit is different,each has its advantages and disadvantages.This paper mainly studies the feedback and compound noise reduction.From the specific mode of realization,there are simulation and digital methods.This paper makes a theoretical analysis from the different system architecture and simulation implementation,and tests and analyses the corresponding prototype of the developed prototype.The pickup and secondary sound sources are the key devices to reduce the noise.The performance of frequency response and sensitivity plays an important role in the noise reduction effect.In this paper,a variety of types of microphone and secondary sound source with different parameters are used to verify and compare the results,and the optimal selection is determined.The structural characteristics such as acoustic cavity design,ear mask,ear pad and ear cavity have great influence on noise reduction and product experience.This paper proves its effect and influence on the active noise reduction performance through test and analysis.The design of noise reduction circuit can be achieved by using professional noise reduction chips or using discrete components to independently design noise reduction circuits.The use of professional chips can easily achieve better noise reduction results,while the use of discrete components can allow designers to understand the noise reduction principles at a deeper level.,If the design is good,it can achieve better noise reduction effect.This paper will adopt specialized chip and discrete components to implement two different architecture noise reduction headset design.At last,because of the professionalism and pertinence of acoustic measurement,this paper expounds the matters which should be paid attention to in the active noise reduction headset test from the angle of acoustic measurement method,and analyzes and summarizes the test of the actual engineering prototype.