CCD图示法对声音频率信息的检测

Detection of sound frequency information based on CCD graphic method

借助CCD图像传感器拍摄不同频率声激励下膜片振动状态,通过图像处理的方法对获取的图片进行频率—位移以及频率—振动幅度面积的特征提取和分析。选取34mm大振膜金属膜片作为介质目标物,实验环境为超静音室暗室环境。采用帧差法将运动目标检测出来并利用二维空间的欧氏距离计算出无声静止时刻和有声激励时移动的位移差,从而得出位移和频率的关系。实验表明,当使用同一声压级不同频率的纯音信号激励膜片时,像素位移差随着频率呈现一定规律。当频率在1800Hz左右时位移达到最大,可推测此振膜谐振频率为1800Hz,这与声学测量下膜片的谐振频率是一致的。为测量物体谐振频率提供新的方法。

Use the CCD image sensor to capture the vibration state of the diaphragm under different frequency excitations,and the image is extracted and analyzed by frequency-displacement and frequency-vibration amplitude area.A 34mm large diaphragm metal diaphragm is selected as the medium target,and the experimental environment is the dark room environment in which the headlights were turned off in the ultra-quiet room.The moving object is detected by the frame difference method and the Euclidean distance in the two-dimensional space is used to calculate the displacement between the silent stationary moment and the moving excitation,so that the relationship between displacement and frequency is obtained.Experiments show that when a pure tone signal with different frequencies of the same sound pressure level is used to excite the diaphragm,the pixel displacement difference exhibits a certain regularity with frequency.When the frequency is around 1 800 Hz,the displacement reaches the maximum.It can be inferred that the resonant frequency of the diaphragm is 1 800 Hz,which is consistent with the resonant frequency of the diaphragm under acoustic measurement.This paper provides a new method for measuring the resonant frequency of an object,and also lays a foundation for the image to detect sound and restore sound.