text: from chapter2_基础.soundBase import *
  from chapter3_分析实验.lpc import *
  from scipy.signal import lfilter
  
  data, fs = soundBase('C3_5_y.wav').audioread()
  L = 240
  x = data[8000:8000 + L]
  x = (x - np.mean(x)) / np.std(x)
  p = 12
  ar, G = lpc_coeff(x, p)
  b = np.zeros(p + 1)
  b[0] = 1
  b[1:] = -ar[1:]
  est_x = lfilter(b, 1, x)
  plt.subplot(2, 1, 1)
  plt.plot(x)
  plt.subplot(2, 1, 2)
  plt.plot(est_x)
  plt.savefig('images/lpc.png')
  plt.close()
  