Method and apparatus for fetal audio stimulation

• US 6,709,407 B2
• Filed: 10/30/2001
• Issued: 03/23/2004
• Est. Priority Date: 10/30/2001
• Status: Expired due to Term

• Current Assignee: Mayo Foundation For Medical Education And Research (Mayo Clinic)
• Original Assignee: Mayo Foundation For Medical Education And Research (Mayo Clinic)
• Inventors: Fatemi, Mostafa
• Primary Examiner(s): MARMOR II, CHARLES ALAN
• Application Number:
  US10/016,250
• Publication Number:
  US 20030083595A1
• Time in Patent Office: 875 Days
• Field of Search: 600/437, 600/443, 600/552, 600/559, 600/591, 600/27, 600/28, 128/897, 128/898, 381/301, 381/312, 381/326, 381/332, 381/333, 381/385, 381/388, 381/151, 735/85
• US Class Current: 600/559
• CPC Class Codes: A61B 5/12 Audiometering
• CPC Class Codes: A61B 8/0866 involving foetal diagnosis; pre-natal or peri-natal diagnosis of the baby

Abstract

The present invention is a method and apparatus for applying a focused, directed audio beam at a fetus to stimulate the fetus in utero. An ultrasound signal is amplitude modulated with an audio range signal, and directed to an ultrasound transducer positioned on the abdomen of a pregnant woman. A focused beam from the ultrasound transducer is directed at the head of a fetus, wherein the resultant audio signal stimulates the middle ear, causing the fetus to move. Motion of the fetus can be tracked to test hearing in individual ears or to test the general health of the fetus. Furthermore, the focused beam can be successively directed at the fetus to cause to the fetus to move to a selected location in the womb for clinical testing or delivery.

Claims

1. A stimulation device for stimulating hearing in a middle ear of a fetus in utero, the stimulation device comprising:

an RF generator generating a carrier signal;

an audio generator generating an audio range signal;

an amplitude modulator, electrically coupled to receive the carrier signal from the RF generator and the audio range signal from the audio generator, the amplitude modulator being operable to modulate the carrier signal with the audio range signal to produce a modulated stimulation signal; and

an ultrasound transducer electrically coupled to receive the modulated stimulation signal and being operable to convert the signal to a focused beam;

wherein the ultrasound transducer is adapted to be acoustically coupled to the fetus and positioned to direct the focused beam at an ear of the fetus to stimulate hearing and movement.

2. The apparatus as defined in claim 1 further comprising an amplifier electrically coupled between the amplitude modulator and the ultrasound stimulation transducer.

3. The apparatus as defined in claim 2, further comprising an amplitude control potentiometer electrically coupled in a feedback loop of the amplifier.

4. The apparatus as defined in claim 1, further comprising:

a gate electrically coupled to receive the modulated signal from the amplitude modulator and to provide the modulated signal to the ultrasound transducer; and

a gate control switch, the gate control switch being selectively activated to activate the gate, wherein the modulated signal is provided to the ultrasound stimulation transducer.

5. The apparatus as defined in claim 1, further comprising a frequency selector switch electrically coupled to the audio generator, the frequency selector switch being activated to select between a plurality of audio range signals.

6. The apparatus as defined in claim 1, further comprising:

a demodulator circuit electrically coupled to receive the modulated signal from the amplitude modulator, the demodulator circuit producing a demodulated audio signal; and

an earphone, electrically coupled to receive the demodulated audio signal from the demodulator circuit, wherein the audio signal produced by the earphone can be monitored by a user to determine when the fetus is being stimulated.

7. The apparatus as defined in claim 1, further comprising:

a strip chart recorder; and

a strip chart marker switch electrically coupled to the strip chart recorder, the strip chart marker switch being selectively activated to provide an indication to the strip chart recorder when a motion of the fetus is detected.

8. The apparatus as defined in claim 1 further comprising:

a fetal monitor probe acoustically coupled to the fetus; and

a Doppler fetal monitor electrically coupled to receive a signal indicative of motion from the fetal monitor probe.

9. The apparatus as defined in claim 8, further comprising:

a strip chart recorder; and

a chart marker, the chart marker being electrically coupled to receive a signal indicative of fetal motion from the Doppler fetal monitor and to provide a signal indicative of fetal motion to the strip chart recorder when a fetal motion event is detected.

10. The apparatus as defined in claim 1, further comprising:

a receiving transducer;

a mixer circuit, electrically coupled to receive the modulated signal from the amplitude modulator and to receive a reflected signal from the receiving transducer;

wherein the mixer circuit down mixes the modulated and reflected signals to produce a down-mixed signal; and

a low pass filter electrically coupled to receive the down-mixed signal from the mixer circuit, the low pass filter filtering the down-mixed signal to produce a Doppler shift signal indicative of a movement of the fetus.

11. The apparatus as defined in claim 10, further comprising a monitor for monitoring the Doppler shift signal.

12. The apparatus as defined in claim 11, wherein the monitor is a video monitor.

13. The apparatus as defined in claim 11, wherein the monitor is an audio monitor.

14. The apparatus as defined in claim 1, further comprising:

an arm having a first end and second end, the ultrasound transducer being pivotally coupled to the first end of the arm wherein the ultrasound transducer is adapted to be selectively directed at the head of the fetus;

a receiving transducer, the receiving transducer being pivotally coupled to the second end of the arm, wherein the receiving transducer is adapted to be selectively directed at the heart of the fetus; and

a Doppler fetal monitor electrically coupled to receive a signal indicative of a motion of the fetus from the receiving transducer.

15. A method for producing a localized sound in a maternal abdomen, the method comprising the following steps:

generating a carrier signal in an ultrasound range;

modulating the carrier signal with an audio range signal to produce a modulated signal;

applying the modulated signal to an ultrasound stimulation transducer to produce a focused beam; and

acoustically coupling the ultrasound stimulation transducer to the abdomen and directing the focused beam at a head of a fetus in utero, wherein a resultant force vibrates the middle ear of the fetus in the audio range.

16. The method as defined in claim 15, further comprising the step of applying the modulated signal to a demodulator to produce a demodulated audio signal.

17. The method as defined in claim 16, further comprising the steps of:

monitoring the demodulated audio signal;

monitoring motion of the fetus; and

correlating the motion of the fetus with the demodulated audio signal.

18. The method as defined in claim 15, further comprising the step of detecting audio-induced motion of the fetus with a Doppler motion detector.

19. The method as defined in claim 15, further comprising the steps of:

focusing a receiving transducer for detecting signals in the same frequency range as the audio range signal at the same location as the ultrasound stimulation transducer; and

monitoring a reflected signal to detect a Doppler shift indicative of motion of the fetus.

20. The method as defined in claim 15, further comprising the steps of:

pivotally mounting the ultrasound stimulating transducer to a first end of an arm;

pivotally mounting a receiving transducer to the second end of the arm;

coupling the receiving transducer to a fetal monitor, monitoring a heart beat of the fetus with the fetal monitor, tracking fetal movement with the fetal monitor; and

correlating the motion to a location of the fetal ear.

21. The method as defined in claim 20, further comprising the step of determining the orientation angle of the stimulation transducer by evaluating a heart to ear distance, a focal length of the ultrasound transducer, a focal length of the receiving transducer, and a length of the arm.