Ultrasonic blood flow doppler audio with pitch shifting

An ultrasonic diagnostic imaging system which produces a Doppler audio signal of blood flow comprising:

• an ultrasound probe, operating at an ultrasonic Doppler transmit frequency f0, which acquires Doppler ultrasound signals referenced to the Doppler transmit frequency from a location of blood flow;
• a Doppler demodulator, responsive to the Doppler ultrasound signals, which produces Doppler shift signals from the velocity of blood flow in an audio frequency band;
• a Doppler information display, responsive to Doppler shift signals, which displays blood flow velocity information based upon the Doppler shift;
• an audio Doppler system, responsive to the Doppler shift signals, which produces pitch-shifted audio Doppler without changing the displayed blood flow velocity,
• wherein the audio Doppler system is responsive to the user control to shift the pitch of the Doppler-shifted signals by a fractional or integer number of octaves so as to preserve the timbre of audio Doppler sounds.