  We present a general framework where the effective field theory of single
field inflation is extended by the inclusion of operators with mass dimension 3
and 4 in the unitary gauge. These higher dimensional operators introduce
quartic and sextic corrections to the dispersion relation. We study the regime
of validity of this extended effective field theory of inflation and the effect
of these higher dimensional operators on CMB observables associated with scalar
perturbations, such as the speed of sound, the amplitude of the power spectrum
and the tensor-to-scalar ratio. Tensor perturbations remain instead, unaltered.
