Pass-by noise signal is nonstationary and time variant. It is difficult to identify sound sources accurately by the traditional FFT method. A noise sources identification technique was developed by the Morlet wavelet transforms (MWT). Applying the method to view the correlation between the standard measuring point noise and near field noises of the engine compartment, we obtained the cross wavelet transform and wavelet coherence for examining relationships in time frequency space between two time series. The contrast between MWT and FFT methods demonstrates that the MWT method can better identify noise correlation under the condition of low signal-to-noise ratio (SNR) levels and short time spans. 