问题 I would like to make a 5-band audio equalizer (60Hz, 230Hz, 910Hz, 4kHz, 14kHz) using AVAudioEngine . I would like to have the user input gain per band through a vertical slider and accordingly adjust the audio that is playing. I tried using AVAudioUnitEQ to do this, but I hear no difference when playing the audio. I tried to hardcode in values to specify a gain at each frequency, but it still does not work. Here is the code I have: var audioEngine: AVAudioEngine = AVAudioEngine() var