We experimentally observed the spatiotemporal velocity field of modulated waves (quasiperiodic mode) in a Couette-Taylor system for Reynolds number 9 less-than-or-equal-to R/R(c) less-than-or-equal-to 28. A power spectrum averaged over four axial wavelengths showed clear evidence of the coexistence of two quasiperiodic modes for a wide range of Reynolds number and the first azimuthal wave mode disappeared at R/R(c) almost-equal-to 18.