面向便携式野战医疗装备语音交互的小尺寸双麦前端系统设计

Design of smart dual-microphone front-end system for speech interaction of portable field medical equipment

目的:针对野战噪声条件下便携式野战医疗装备的语音交互性能受到影响的问题,设计一种小尺寸双麦前端系统。方法:该系统基于最小二乘准则实现小尺寸双麦波速形成,进而实现前端语音增强。系统硬件主要由双麦、信号预处理模块、嵌入式处理器、模拟数字转换器(analog to digital converter,ADC)、数字模拟转换器(digital to analog converter,DAC)、供电模块等组成。其中,双麦采用2个贴片式微机电系统(micro electro mechanical system,MEMS)麦克风,信号预处理模块、ADC、DAC内置在通用音频编码器WM8978中,嵌入式处理器采用STM32F405系列处理器,供电模块采用LM1117电压调节器芯片。系统软件采用KeilμVision4开发软件编译和测试。为验证该系统的性能,进行指向性实验和语音增强实验。结果:指向性实验结果表明,在0.5~2.0 kHz频率范围内,该系统在各频点的指向性一致性较好;语音增强实验结果表明,在枪声、监护仪报警、医疗器皿碰撞3类非平稳噪声条件下,该系统可有效提升语音的音质及识别率。结论:该系统能实现语音增强,可为便携式野战医疗装备的语音交互提供有效的支持。

Objective To design a small-size dual-microphone front-end system to solve the problems of the portable field medical equipment in speech interaction due to noises in field conditions.Methods The system realized small-size dual-microphone beamforming based on the least squares criterion and then implemented front-end speech enhancement,which was composed of dual microphones(SMD micro electro mechanical system microphone),a signal preprocessing module,an embedded processor(STM32F405 series processor),an analog to digital converter(ADC),an digital to analog converter(DAC)and a power supply module.The signal preprocessing module,ADC and DAC were built into the general-purpose audio encoder WM8978,and a LM1117 voltage regulator chip was adopted as the power supply module.KeilμVision4 development software was used for software compiling and testing.Directivity experiment and speech enhancement experiment were carried out to verify the performance of the system.Results Directivity experiment showed that the system gained high directivity consistency at each frequency point in the frequency range of 0.5 to 2.0 kHz;speech enhancement experiment indicated that the system effectively improved the sound quality and recognition rate of speech under the conditions of three types of non-smooth noises,namely,gunshot,alarm of the monitor and collision of the medical utensils.Conclusion The system developed can realize speech enhancement to facilitate speech interaction of the portable field medical equipment.