Does the Doppler effect occur when the source and observer are both moving in the same direction at the same speed? If so, how would this affect the perceived frequency? a b d The Doppler effect occurs not only for sound, but for any wave when there is relative motion between the observer and the source. Doppler shifts occur in the frequency of sound, light, and water waves. Yes, the perceived frequency will be same as the source frequency. Yes, the perceived frequency will be less than the source frequency. No, the perceived frequency will be less than the source frequency. No, the perceived frequency will be the same as the source frequency. Submit