  An elegant approach, which incorporates the effect of the stringy spacetime
uncertainty relation, to calculate power spectra of fluctuations during
inflation has been suggested by Brandenberger and Ho. In this approach, one of
important features is the appearance of an upper bound on the comoving momentum
$k$, at which the stringy spacetime uncertainty relation is saturated. As a
result, the time-dependent upper bound leads us to choose naturally a set of
initial vacua for each mode, in which the stringy uncertainty relation is
saturated. In this note, with that set of vacua we calculate power spectrum of
curvature fluctuation for a power law inflation, up to the leading order of a
parameter describing the spacetime noncommutativity. It turns out that this
choice of initial vacuum has a significant effect on the power spectrum of
fluctuations.
