Acoustic detection for respiratory treatment apparatus
Methods and apparatus provide acoustic detection for automated devices such as respiratory treatment apparatus. In some embodiments of the technology, acoustic analysis of noise or sound pulses, such as a cepstrum analysis, based on signals of a sound sensor ( 104 ) permits detection of obstruction (O) such as within a patient interface, mask or respiratory conduit ( 108 ) or within patient respiratory system. Some embodiments further permit detection of accessories such as an identification thereof or a condition of use thereof, such as a leak. Still further embodiments of the technology permit the detection of a patient or user who is intended to use the automated device.
1. A device for use with a respiratory treatment apparatus comprising a motor and impeller configured to generate a supply of pressurized air from an outlet along an artificial airpath connected to a patient interface and thereafter into a patient for treatment, the device comprising:
a sensor configured to receive and transduce (a) a first acoustic signal generated by operation of the motor and impeller, and (b) a second acoustic signal (i) representative of the first acoustic signal having been reflected back from the patient interface along the artificial airpath, and (ii) corresponding to the patient interface; and
a controller configured to:
process the transduced first acoustic signal and second acoustic signal, and
detect the patient interface connected to the artificial airpath based on the processed transduced second acoustic signal, wherein the controller is configured to identify, using the processed transduced second acoustic signal, a model of the patient interface so as to differentiate the model of the patient interface from other patient interface models.
2. The device of claim 1 , wherein the first acoustic signal is either an acoustic impulse or a continuous acoustic signal.
3. The device of claim 1 , wherein the controller processes the transduced first and second acoustic signals by cepstrum analysis.
4. The device of claim 1 , wherein the sensor is one of the group consisting of: a microphone; a pressure sensor; and a flow sensor.
5. The device of claim 1 , wherein the controller is further configured to transfer information about the connected patient interface to a computer.
6. The device of claim 1 , wherein the sensor is mounted or encapsulated in or positioned proximal to the outlet of the respiratory treatment apparatus.
7. The device of claim 1 wherein the detecting further comprises (a) identifying a mask model, or (b) detecting a leak associated with the patient interface.
8. The device of claim 1 wherein to process and detect, the controller is configured to evaluate quefrency data.
9. The device of claim 8 wherein to process and detect, the controller is configured to compare measured and stored responses represented by the quefrency data.
10. The device of claim 9 wherein to compare the measured and stored responses, the controller is configured to compute a cross-correlation of the measured and stored responses, and detect one or more peaks in the cross-correlation.
11. The device of claim 10 wherein the controller is configured to evaluate a time position of the detected one or more peaks.
12. The device of claim 9 wherein to compare the measured and stored responses, the controller is configured to perform a least squares operation with the measured and stored responses.
13. The device of claim 1 wherein the controller is further configured to adjust a setting of the respiratory treatment apparatus based on the identified model of the patient interface.
14. The device of claim 13 wherein in response to the detection, the controller selects (a) operating parameters of a flow generator or (b) settings for control of a flow generator.
15. The device of claim 1 wherein the controller is configured to operate the motor and impeller to produce the first acoustic signal.
16. A method for use with a respiratory treatment apparatus comprising a motor and impeller configured to generate a supply of pressurized air from an outlet along an artificial airpath connected to a patient interface and thereafter into a patient for treatment, the method comprising:
transducing, with a sensor, (a) a first acoustic signal generated by operation of the motor and impeller, and (b) a second acoustic signal (i) representative of the first acoustic signal having been reflected back from the patient interface along the artificial airpath, and (ii) corresponding to the patient interface; and
with a controller coupled with the sensor:
processing the transduced first acoustic signal and the second acoustic signal, and
detect the patient interface connected to the artificial airpath based on the processed second acoustic signal, wherein the controller identifies, using the processed transduced second acoustic signal, a model of the patient interface so as to differentiate the model of the patient interface from other patient interface models.
17. The method of claim 16 , wherein the processing the transduced first and second acoustic signals comprises performing a cepstrum analysis.
18. The method of claim 16 , wherein the sensor is one of the group consisting of: a microphone; a pressure sensor; and a flow sensor.
19. The method of claim 16 , further comprising, with the controller, (a) transferring information about the connected patient interface to a computer; and/or (b) operating the motor and impeller to produce the first acoustic signal.
20. The method of claim 16 , wherein the sensor is mounted or encapsulated in or positioned proximal to the outlet of the respiratory treatment apparatus.
21. The method of claim 16 wherein the detecting further comprises (a) identifying a mask model, or (b) detecting a leak associated with the patient interface.
22. The method of claim 16 the processing comprises evaluating quefrency data.
23. The method of claim 22 , wherein the processing comprises comparing measured and stored responses represented by the quefrency data.
24. The method of claim 23 wherein the comparing the measured and stored responses, comprises computing a cross-correlation of the measured and stored responses, and detecting one or more peaks in the cross-correlation.
25. The method of claim 24 further comprising evaluating a time position of the detected one or more peaks.
26. The method of claim 23 wherein the comparing the measured and stored responses comprises performing a least squares operation with the measured and stored responses.
27. The method of claim 16 further comprising, by the controller, adjusting a setting of the respiratory treatment apparatus based on the identified model of the patient interface.
28. The method of claim 27 wherein in response to the detection, the controller selects (a) operating parameters of a flow generator, or (b) settings for control of a flow generator.