I am currently reading a paper about speech enhancement. The paper uses Spectral Subtraction Method. On that section, The paper stated that ω is the "discrete angular frequency index of the frames"
Question: What is the discrete angular frequency index? Is it part of Short Time Fourier Transform?
Assume that the noisy speech $\boldsymbol{y[n]}$ can be expressed as $\boldsymbol{y[n] = s[n] + d[n]}$, where $\boldsymbol{s[n]}$ is the clean speech and $\boldsymbol{d[n]}$ is the additive noise. As the enhancement is carried out according to the frame, the above model can be expressed as $$y(n,k) = s(n,k) + d(n,k),\quad n=0,1,2,\ldots,(N-1);\quad k=1,2,\ldots,N\tag{1}$$ Here $n$ is the discrete time index, $k$ is the frame number and $N$ is the length of the frame. $$y(\omega,k) = S(\omega,k) + D(\omega,k)\tag{2}$$ Here $\omega$ is the discrete angular frequency index of the frames.
The paper is:
Navneet Upadhyay and Rahul Kumar Jaiswal: "Single Channel Speech Enhancement: Using Wiener Filtering with Recursive Noise Estimation", Procedia Computer Science, Volume 84, 2016, Pages 22-30, doi:10.1016/j.procs.2016.04.061.