便携式听觉稳态诱发响应声音刺激器设计

Portable stimuli generator for auditory steady state responses

目的 听觉稳态诱发响应（auditory steady state response,ASSR）对大脑的听觉系统研究有重要意义,但传统的用于ASSR实验的刺激设备较为昂贵且使用不便,本文给出一种便携式听觉刺激器的设计方案.方法 以TI的TMS320C5515芯片作为核心处理器,利用SD卡存储用于声音刺激的配置文件以及声音数据,通过主芯片提供的SD卡接口及DMA通道读取声音数据,然后经过I2S总线,传递数据至音频编解码器中,最后完成声音的播放.该系统提供可视化的界面,供用户选择配置文件.同时提供一个基于MATLAB的工具包,用于将普通的音乐格式转化为系统兼容的声音数据格式.结果 本系统支持8～ 192 kHz的声音采样率,支持单声道和立体声,支持声音位宽包括16位和32位,且允许输出声压级在87.5 dB的动态范围内变化,变化的步长为0.5dB.为验证本系统的实用性,4个受试参与了一系列ASSR实验,获得了预期的实验结果.结论 本系统可用于ASSR实验中,且系统可保证长时间稳定频率的声音输出,因系统功耗小于200 mW,如果使用1000 mA·h的3.7V的锂电池供电,则系统可持续工作超过18.5 h.

Objective The research for auditory steady state response （ASSR） is important for understanding the auditory system in human brain. Unfortunately, the devices for generating the auditory stimuli in previous research are expensive yet inconvenient. This paper proposes a novel portable auditory stimuli generator for ASSR experiments. Methods The main processor of this system is TI＇s TMS320C5515 digital signal processor （DSP）. A SD card is used to store configuration files and sound files which specify the sound stimuli. The main processor reads data from the SD card through the SD interface and the DMA channel. Then, the data are transmitted from the processor to an audio coder and decoder （CODEC） through the I2S bus and finally achieves the sound playing. A graphic user interface is provided for the user to choose the configuration file. Moreover, a toolbox based on MATLAB is offered to translate the common music formats into the compatible sound format. Results The permissible sampling rates for playback range from 8 kHz to 192 kHz. The channels can be either mono or stereo, and the data resolution can be 16 bits or 32 bits. The playback volume can be adjusted in 87.5 dB＇ s range, and the step for adjustment is O. 5 dB. A series of ASSR experiments have been conducted on 4 subjects of this system. Conclusions, to demonstrate the This system can successfully in the ASSR experiments to provide and stable sound outputs. The system holds feasibility be used long-term a powerconsumption less than 200 mW. With a 1000 mA · h and 3.7 V ＇ s lithium battery, this system can keep oil working for more than 18.5 h.