Which of the following best describes the Doppler frequencies obtained in a clinical assessment of blood velocities in the common femoral artery?
1) audible and much less than the frequency of the emitted sound beam
2) ultrasonic and similar to the frequency of the emitted sound beam
3) audible and similar to the frequency of the emitted sound beam
4) ultrasonic but much less than the frequency of the emitted sound beam
5) infrasonic