Determining usability of an acoustic signal for physiological monitoring using frequency analysis

• US 9,241,672 B2
• Filed: 02/09/2012
• Issued: 01/26/2016
• Est. Priority Date: 02/09/2012
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Lai, Yungkai Kyle
• Primary Examiner(s): Kahelin, Michael
• Assistant Examiner(s): TRAN, THO Q
• Application Number:
  US13/369,463
• Publication Number:
  US 20130211274A1
• Time in Patent Office: 1,447 Days
• Field of Search: 600/529, 600/586, 600/528
• US Class Current: 1/1
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 7/00 Instruments for auscultation

Abstract

An acoustic physiological monitoring system and method wherein the usability for physiological monitoring of time segments of an acoustic signal recording body sounds is determined using frequency analysis. A time segment of the acoustic signal is filtered into a target portion in a target frequency band and a non-target portion in a non-target frequency band. Energies of the target portion and the non-target portion are computed. A usability indicator for the time segment is computed using the energies. The usability of the time segment is determined using the usability indicator. A physiological parameter estimate is selectively calculated using the time segment based on the usability of the time segment. Finally, information based on the physiological parameter estimate is outputted.

Claims

1. An acoustic physiological monitoring method, comprising the steps of:

detecting by a physiological monitoring system, using a sound transducer, body sounds;

generating by the system an acoustic signal expressing the body sounds;

filtering by the system a time segment of the signal into a target portion in a target frequency band and at least one non-target portion in at least one non-target frequency band;

computing by the system an energy of the target portion;

computing by the system an energy of the non-target portion;

computing by the system a plurality of usability indicators for the time segment by applying a plurality of different rules based at least in part on the energy of the target portion and the energy of the non-target portion, each of the usability indicators providing a separate indication of whether the time segment is clear or mixed;

determining by the system a usability of the time segment including assigning to the time segment a probability greater than zero and less than one that the time segment is usable based at least in part on the usability indicators and one or more probabilities that one or more neighboring time segments is usable;

selectively calculating by the system a physiological parameter estimate using the time segment based at least in part on the usability of the time segment; and

outputting by the system information based at least in part on the physiological parameter estimate.

2. The method of claim 1, wherein the target portion isolates respiration sounds.

3. The method of claim 1, wherein the target frequency band and the non-target frequency band are adjacent in the frequency domain.

4. The method of claim 1, wherein the target frequency band and the non-target frequency band are non-overlapping in the frequency domain.

5. The method of claim 1, wherein at least one of the usability indicator is determined using a ratio of the energy of the target portion to the energy of the non-target portion.

6. The method of claim 1, wherein the filtering step is performed using a plurality of bandpass filters.

7. The method of claim 1, wherein the physiological parameter estimate is a respiration parameter estimate.

8. A physiological monitoring device, comprising:

a sound capture system configured to detect, using a sound transducer, body sounds and generate an acoustic signal expressing body sounds;

an acoustic signal processing system configured to receive from the sound capture system the signal, filter a time segment of the signal into a target portion in a target frequency band and at least one non-target portion in at least one non-target frequency band, compute an energy of the target portion, compute an energy of the non-target portion, compute at least one usability indicators for the time segment by applying a plurality of different rules based at least in part on the energy of the target portion and the energy of the non-target portion, each of the usability indicators providing a separate indication of whether the time segment is clear or mixed, determine a usability of the time segment including assigning to the time segment a probability greater than zero and less than one that the time segment is usable based at least in part on the usability indicators and one or more probabilities that one or more neighboring time segments is usable and selectively calculate a physiological parameter estimate using the time segment based at least in part on the usability of the time segment; and

a physiological data output system configured to output information based at least in part on the physiological parameter estimate.

9. The device of claim 8, wherein at least one of the usability indicators is determined using a ratio of the energy of the target portion to the energy of the non-target portion.

10. The device of claim 8, wherein the device is portable.