<p>Intermittency measurement in the laminar-to-turbulent transition region was studied through the time-frequency analysis of hot-film output signals. The transition process is an unsteady phenomenon; hence, the signals could not be analyzed using classical signal-processing schemes such as the Fourier transform, which does not consider the possible evolutions in time. Spectrogram plots are used for time-frequency analysis. The analysis shows the existence of instabilities in the spectrogram during the transition from laminar to turbulent flow. The measurement of occurrence times for these instabilities leads to the calculation of intermittency for the transitional flow. Time-frequency analysis enables the evaluation of the intermittency for different disturbance frequencies which is presented for the first time in the current investigation. In addition, several new visualization methods for investigating boundary layer events are presented based on polar diagrams from adjacent hot-film sensors, space-frequency, and time-frequency plots.</p>