Audio effects add depth and character to audio signals, enhancing the overall listening experience. One popular effect is the wah-wah effect, commonly associated with electric guitar solos. In this blog post, we will explore how to implement a wah-wah effect using C++.

What is a Wah-Wah Effect?

The wah-wah effect is a modulation effect that alters the tone of an audio signal by systematically sweeping a bandpass filter up and down the frequency spectrum. The effect mimics the sound of a human voice mouthing the syllables “wah-wah.”

Designing the Wah-Wah Effect

To implement the wah-wah effect, we first need to design a bandpass filter. We can use a second-order IIR (Infinite Impulse Response) filter for this purpose. The cutoff frequency of the filter determines the wah-wah effect’s sweep range.

Here’s an example code snippet in C++ that shows the basic structure of a second-order IIR filter:

class IIRFilter {
public:
  IIRFilter(double cutoffFrequency, double sampleRate) {
    // Calculate filter coefficients
  }

  double process(double input) {
    // Apply filter to input
    // Return the filtered output
  }

private:
  // Filter coefficients and internal state variables
};

Implementing the Wah-Wah Effect

To implement the wah-wah effect, we need to modulate the cutoff frequency of the bandpass filter over time. This modulation is typically controlled by a foot pedal or a LFO (Low-Frequency Oscillator).

Here’s an example code snippet illustrating the concept of wah-wah modulation using an LFO:

class WahWahEffect {
public:
  WahWahEffect(double sweepRange, double modulationRate, double sampleRate) {
    // Create an instance of the bandpass filter
    // Initialize the LFO parameters
  }

  double process(double input) {
    // Calculate LFO value
    // Adjust the cutoff frequency of the bandpass filter
    // Process the input signal through the modulated bandpass filter
    // Return the processed output
  }

private:
  IIRFilter bandpassFilter;
  double lfoValue;
  // LFO parameters and internal state variables
};

Conclusion

Implementing audio effects like the wah-wah effect using C++ allows us to customize and enhance audio signals. By modulating the bandpass filter’s cutoff frequency, we can achieve the distinctive “wah-wah” sound effect. This example provides a basic structure for implementing the wah-wah effect, and you can further refine and optimize it based on your requirements.

#audioeffects #wahwah #C++