I want to shift the response phase of an audio signal (float array, length N, value range -1..1). I'm about using Fast Hartley Transform to transform it to the frequency-domain, process phase shift, then convert back to the time-domain and output the result.
I'm now can do the Hartley transform, and I also can calculate the phase of kth bin:
real(k) = (x(k) + x(-k))/2 imag(k) = (x(k) - x(-k))/2 phase(k) = atan2(imag(k), real(k))
I want to shift the phase(k) by an α degree. What should I do?