We investigate the ability to constrain oscillatory features in the primordial power spectrum using current and future cosmic microwave background observations .
In particular , we study the observability of an oscillation arising from imprints of physics at the cutoff energy scale .
We perform a likelihood analysis on the WMAP data set , and find that the current data set constrains the amplitude of the oscillations to be less than 0.77 at 2 \sigma , consistent with a power spectrum without oscillations .
In addition , we investigate the fundamental limitations in the measurement of oscillation parameters by studying the constraints from a cosmic variance limited experiment .
We find that such an experiment is capable of constraining the amplitude of such oscillations to be below 0.005 , implying that reasonable models with cutoff energy scales \Lambda > 200 H _ { \text { infl } } are unobservable through the microwave background .