code: public float turbulence3(float x, float y, float z, float octaves) {
          float t = 0.0f;
  
          for (float f = 1.0f; f <= octaves; f *= 2)
              t += Math.abs(noise3(f * x, f * y, f * z)) / f;
          return t;
      }
docs: Compute turbulence using Perlin noise.
  
  @param x       the x value
  @param y       the y value
  @param octaves number of octaves of turbulence
  @return turbulence value at (x,y)