Measurement of distortion-product otoacoustic emissions (DPOAEs) is one of the functional tests for the outer hear cells in the cochlea. Since the sound levels of the DPOAEs are quite low, it is easy to be buried in noise especially in the low frequency range, and frequency analysis and time averaging are required to detect them. In this study, focusing on the frequency stability of two stimulus sounds and a most prominent DPOAE-component, we tried to reduce noise floor and shorten the measurement time by choosing an adequate time window length for averaging the sound pressure waveform in the ear canal and the number of the averaging. As a result, it has become possible to measure DPOAEs at the low frequencies around 300 Hz in a relatively short time. Using this method, the changes in the DPOAE level induced by contralateral acoustic stimulation, which are caused by medial olivocochlear reflex, were measured. Although some exceptions were observed, the DPOAE was suppressed with increasing the sound pressure of the contralateral stimulus, and the degree of suppression was greater for the lower-frequency DPOAEs.