Abstract: This study is concerned with the physical interpretations for the statistical uncertainty of the spectral peak energy and peak frequency of the Fourier freyuency spectrum.The local wavelet energy spectrum,based on the wavelet transform,is introduced to analyze the wind wave data obtained in a wind wave channel.It is shown that wave energy exhibits localizations both in scale (frequency) and physical space (time),which implies energy intermittency——the energy at a given frequency may not be evenly distributed in the whole time.Especially,the peak energy and the corresponding peak frequency of a local wavelet energy spectrum have significant fluctuations as time evolves.Such intermittency and fluctuations give appropriate interpretations for the above mentioned statistical uncertainty.