音频均衡器

Question

我正在尝试用 python 制作一个简单的 10 频段均衡器。我已经编写了两个函数来实现此目的，但我有增益问题。我想为每个频段设置增益，但它不起作用。

这里有一个例子。需要一个单通道 wav“audio.wav”文件才能工作。

import numpy as np
import matplotlib.pyplot as plt
import scipy.io.wavfile as wav
from scipy import signal
from scipy.signal import butter, lfilter

def bandpass_filter(data, lowcut, highcut, fs, order=5):
    nyq = 0.5 * fs
    low = lowcut / nyq
    high = highcut / nyq
    b, a = butter(order, [low, high], btype='bandpass')
    filtered = lfilter(b, a, data)
    return filtered

def equalizer_10band (data, fs, gain1=0, gain2=0, gain3=0, gain4=0, gain5=0, gain6=0, gain7=0, gain8=0, gain9=0, gain10=0):
    band1 = bandpass_filter(data, 20, 39, fs, order=2)* 10**(gain1/20)
    band2 = bandpass_filter(data, 40, 79, fs, order=3)*10**(gain2/20)
    band3 = bandpass_filter(data, 80, 159, fs, order=3)*10**(gain3/20)
    band4 = bandpass_filter(data, 160, 299, fs, order=3)* 10**(gain4/20)
    band5 = bandpass_filter(data, 300, 599, fs, order=3)* 10**(gain5/20)
    band6 = bandpass_filter(data, 600, 1199, fs, order=3)* 10**(gain6/20)
    band7 = bandpass_filter(data, 1200, 2399, fs, order=3)* 10**(gain7/20)
    band8 = bandpass_filter(data, 2400, 4999, fs, order=3)* 10**(gain8/20)
    band9 = bandpass_filter(data, 5000, 9999, fs, order=3)* 10**(gain9/20)
    band10 = bandpass_filter(data, 10000, 20000, fs, order=3)* 10**(gain10/20)
    signal = band1 + band2 + band3 + band4 + band5 + band6 + band7 + band8 + band9 + band10
    return signal


freq_s, data = wav.read("audio.wav")

N = len(data)
t  = 1/freq_s * np.arange(N) 
f  = freq_s/N * np.arange(N)

#computing fft of original signal
F_data = np.fft.fft(data)/N

#appying equalizer
equalized = equalizer_10band(data, freq_s, -100,-100,-100,0,0,0,0,0,0,0)

#computing fft of filtered signal
Y = np.fft.fft(equalized)/N

plt.figure(figsize=(10, 8))
plt.subplot(2,1,1)
plt.plot(t, equalized,'-b',label=r"$Filtered amplitude(t)$")
plt.xlabel('time[s]')
plt.subplot(2,1,1)
plt.plot(t, data,'-r',label=r"$Original amplitude(t)$")
plt.xlabel('time[s]')
plt.legend()
plt.grid()

plt.subplot(2,1,2)
plt.plot(f[:N//2],np.abs(F_data[:N//2]),'-r',label=r"$Original magnitude(f)$")
plt.xlabel('f [Hz]')
plt.xlim([0,5e3])
plt.plot(f[:N//2],np.abs(Y[:N//2]),'-b',label=r"$Filtered magnitude(f)$")
plt.xlabel('f [Hz]')
plt.xlim([0,5e3])
plt.legend()
plt.tight_layout()
plt.grid()

在第二张图中，显示了原始信号和滤波信号的频谱重叠，我希望看到滤波信号的前三个频段的频率为零水平，但它们与原始信号大致相同。我还附上了频谱图的快照。

频谱图

你能帮我吗？