sentences:  This is not much of a restriction, since the reassignment operation itself implies that there is some energy to reassign, and has no meaning when the distribution is zero-valued.The short-time Fourier transform can often be used to estimate the amplitudes and phases of the individual components in a "multi-component" signal, such as a quasi-harmonic musical instrument tone.Moreover, the time and frequency reassignment operations can be used to sharpen the representation by attributing the spectral energy reported by the short-time Fourier transform to the point that is the local center of gravity of the complex energy distribution.