Patent Description:
In healthcare scenarios, heart sounds produced by a heart of a subject have been utilized in diagnosing health care issues of the subject. Historically, a care giver (such as a physician) would utilize a stethoscope to listen to the heart sounds of the subject and make inferences regarding the health status of the subject.

Legacy electronic healthcare systems have developed to capture the heart sounds of the subject in place of the care giver. In particular, the legacy electronic healthcare systems can capture the heart sounds and store representations of the heart sounds. In some of these legacy electronic healthcare systems, a sound sensor may be placed on the subject to capture the sounds. <CIT> discloses a device and method for compensating for acoustic attenuation of the human body when analyzing ausculatatory cardiac sounds. <CIT> discloses monitoring of cardiac mechanical and electrical activity using piezoelectric material and signal processing techniques. <CIT> discloses an acoustic monitoring system for measuring physiological parameters of a patient. <CIT> discloses an application server for reducing ambiance noise in an auscultation signal.

The present disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not necessarily drawn to scale, and are used for illustration purposes only. Where a scale is shown, explicitly or implicitly, it provides only one illustrative example. In other embodiments, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

There is disclosed herein examples of systems and methods of processing captured heart sounds with frequency-dependent normalization. Based on an amount of attenuation of a first heart sound, a second heart sound can be normalized by modifying portions of the second heart sound by amounts determined based on frequencies of the portions. Accordingly, the systems and methods disclosed herein can result in different amounts of modification of different portions of the second heart sound based on the different frequencies of the portions.

In certain embodiments, one or more computer-readable media having instructions stored thereon are provided according to claims <NUM> or <NUM>.

In certain embodiments, a system for capturing heart sounds of a subject, comprising one or more sound sensors is provided according to claims <NUM> or <NUM>.

In certain embodiments, a method of normalizing heart sounds, is provided according to claims <NUM> or <NUM>.

The following disclosure provides many different embodiments, or examples, for implementing different features of the present disclosure. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. Further, the present disclosure may repeat reference numerals and/or letters in the various examples, or in some cases across different figures. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a specific relationship between the various embodiments and/or configurations discussed. Different embodiments may have different advantages, and no particular advantage is necessarily required of any embodiment.

Disclosed herein are systems and methods for processing heart sounds with frequency-dependent normalization. Healthcare systems that capture heart sounds often utilize one or more sound sensors placed on the skin of a subject. However, placement of the sound sensors can result in attenuation of the heart sounds captured by the healthcare systems, often inadvertently. For example, improper placement of the sound sensors and/or the sound sensors being improperly attached to the skin of the subject can result in attenuation of the heart sounds. Further, the different portions of the heart sounds can be attenuated by different amounts based on the frequency of the different portions of the heart sounds. Failing to consider the attenuation of the heart sounds and the different amounts of attenuation of the different portions of the heart sounds based on the different frequencies can result in improper representations of the heart sounds and/or processing of improper representations of the heart sounds.

The systems and the methods disclosed herein can take into consideration the attenuation of the heart sound and the different amounts of attenuation of the different portions of the heart sounds based on the different frequencies. In particular, the systems and methods disclosed herein can compare a capture of a first heart sound with a control for the first heart sound to determine an amount of attenuation between the capture of the first heart sound and the control for the first heart sound, where the first heart sound should have a uniform amplitude across measurements. Each measurement may include one or more cardiac cycles. The systems and methods can utilize the amount of attenuation to modify captures of other heart sounds, where different portions of the other heart sounds may be modified by different amounts based on the different frequencies of the different portions.

<FIG> illustrates an example procedure <NUM> for processing heart sounds, according to embodiments herein. In particular, the procedure <NUM> may include normalization of one or more captures of heart sounds of a subject with a frequency-based approach.

The procedure <NUM> may initiate by receiving a representation of one or more cardiac cycles as input <NUM>. For example, the input <NUM> may comprise an electrical signal that represents heart sounds included in the cardiac cycles. The electrical signal may be produced by a sound sensor that senses the heart sounds produced by the cardiac cycles and generates the electrical signal that represents the heart sounds. For example, the amplitude of the electrical signal can indicate an amplitude of the sound. Further, the electrical signal may be a time-domain representation of the heart sounds, where the electrical signal indicates the amplitude of the heart sounds over time.

<FIG> illustrates an example electrical signal <NUM> that may be received as the input <NUM> of the procedure <NUM>, according to embodiments herein. In particular, the electrical signal <NUM> illustrates a single cardiac cycle captured from the subject. A cardiac cycle includes a single heartbeat and the electrical signal <NUM> illustrates the heart sounds produced by a heart of the subject during the single heartbeat. The single heartbeat produces an S1 heart sound, an S2 heart sound, an S3 heart sound, and an S4 heart sound in the illustrated instance. In other instances, the S3 heart sound and/or the S4 heart sound may be omitted from the heart sounds produced by the heart of the subject during the heartbeat. While a single cardiac cycle is shown in the illustrated instance, it should be understood that in other instances multiple cardiac cycles may be received as the input <NUM> of the procedure <NUM>. The cardiac cycle and/or the multiple cardiac cycles may be captured during a test cycle of a heart sound capture system.

The procedure <NUM> may include performing decomposition of the electrical signal in <NUM>. The decomposition of the electrical signal may include identifying the different heart sounds from the electrical signal. In particular, the S1 heart sound, the S2 heart sound, the S3 heart sound, and/or the S4 heart sound represented by the electrical signal may be identified. Each of the heart sounds may be identified based on the amplitude of the heart sounds represented by the electrical signal, the frequency of the heart sounds represented by the electrical signal, the duration of the heart sounds represented by the electrical signal, the order of the heart sounds represented by the electrical signal, or some combination thereof.

<FIG> illustrates the heart sounds as identified within the procedure <NUM>, according to embodiments herein. For example, the electrical signal <NUM> may include representations of one or more heart sounds that occur discrete in time. A cardiac cycle can include an S1 heart sound, an S2 heart sound, an S3 heart sound, an S4 heart sound, or some combination thereof. In the illustrated instance, the electrical signal <NUM> includes representations of an S1 heart sound <NUM>, an S2 heart sound <NUM>, an S3 heart sound <NUM>, and an S4 heart sound <NUM>. In the decomposition of the electrical signal <NUM>, the S1 heart sound <NUM>, the S2 heart sound <NUM>, the S3 heart sound <NUM>, and the S4 heart sound <NUM> can be identified, as indicated by the labeling of the heart sounds in <FIG>. In other instances, representations of the S3 heart sound <NUM> and/or the S4 heart sound <NUM> may be omitted, such as when a heartbeat of the subject does not produce the S3 heart sound <NUM> and/or the S4 heart sound <NUM> (which can be a normal occurrence for a subject). In these instances, any combination of the S1 heart sound <NUM>, the S2 heart sound <NUM>, the S3 heart sound <NUM>, and/or the S4 heart sound <NUM> can be identified while the heart sounds omitted from the electrical signal <NUM> may not be identified.

In some embodiments, the electrical signal <NUM> can be divided into different parts for processing during the decomposition of the electrical signal. In particular, the electrical signal <NUM> may be divided into different parts, where each part corresponds to a corresponding, identified heart sound. For example, a first part can include the S1 heart sound <NUM>, a second part can include the S2 heart sound <NUM>, a third part can include the S3 heart sound <NUM>, and a fourth part can include the S4 heart sound <NUM> in the illustrated instance. In other embodiments, the electrical signal <NUM> can be divided into different parts at a later point during the procedure <NUM>.

The procedure <NUM> may further include performing a spectral analysis of the electrical signal in <NUM>. In particular, spectral analysis may be performed for each of the heart sounds identified in the decomposition of the electrical signal performed in <NUM>. The spectral analysis can include converting the representations of the heart sounds into frequency-domain representations of the heart sounds. The representations of the heart sounds can be converted into frequency-domain representations by applying a Fourier transform to each of the representations of the heart sounds. For example, a Fourier transform applied to each of the representations can comprise a fast Fourier transform, a discrete Fourier transform, a continuous Fourier transform, or some combination thereof. For example, the S1 heart sound <NUM>, the S2 heart sound <NUM>, the S3 heart sound <NUM>, and the S4 heart sound <NUM> can be converted into frequency-domain representations of each in the illustrated instance. The different parts of the electrical signal <NUM> corresponding to the different heart sounds can be converted separately.

<FIG> illustrates an example frequency-domain representation <NUM> of an S1 heart sound, according to embodiments herein. For example, the frequency-domain representation <NUM> may be a frequency-domain representation of the S1 heart sound <NUM>. The frequency-domain representation <NUM> may be produced by performing the spectral analysis in <NUM> on part of the electrical signal <NUM> corresponding to the S1 heart sound <NUM>. As can be seen, the frequency-domain representation <NUM> shows the amplitude of different portions of the S1 heart sound <NUM> corresponding to different frequencies. For example, the frequency-domain representation <NUM> shows a first peak <NUM> at a first frequency and a second peak <NUM> at a second frequency. In other embodiments, peaks may occur at different frequencies and/or may have different amplitudes in the frequency-domain representation <NUM>.

<FIG> illustrates an example frequency-domain representation <NUM> of an S2 heart sound, according to embodiments herein. For example, the frequency-domain representation <NUM> may be a frequency-domain representation of the S2 heart sound <NUM>. The frequency-domain representation <NUM> may be produced by performing the spectral analysis in <NUM> on part of the electrical signal <NUM> corresponding to the S2 heart sound <NUM>. As can be seen, the frequency-domain representation <NUM> shows the amplitude of different portions of the S2 heart sound <NUM> corresponding to different frequencies. For example, the frequency-domain representation <NUM> shows a first peak <NUM> at a first frequency, a second peak <NUM> at a second frequency, and a third peak <NUM> at a third frequency. In other embodiments, peaks may occur at different frequencies and/or may have different amplitudes in the frequency-domain representation <NUM>.

<FIG> illustrates an example frequency-domain representation <NUM> of an S3 heart sound, according to embodiments herein. For example, the frequency-domain representation <NUM> may be a frequency-domain representation of the S3 heart sound <NUM>. The frequency-domain representation <NUM> may be produced by performing the spectral analysis in <NUM> on part of the electrical signal <NUM> corresponding to the S3 heart sound <NUM>. As can be seen, the frequency-domain representation <NUM> shows the amplitude of different portions of the S3 heart sound <NUM> corresponding to different frequencies. For example, the frequency-domain representation <NUM> shows a peak <NUM> at a frequency. In other embodiments, peaks may occur at different frequencies and/or may have different amplitudes in the frequency-domain representation <NUM>.

<FIG> illustrates an example frequency-domain representation <NUM> of an S4 heart sound, according to embodiments herein. For example, the frequency-domain representation <NUM> may be a frequency-domain representation of the S4 heart sound <NUM>. The frequency-domain representation <NUM> may be produced by performing the spectral analysis in <NUM> on part of the electrical signal <NUM> corresponding to the S4 heart sound <NUM>. As can be seen, the frequency-domain representation <NUM> shows the amplitude of different portions of the S4 heart sound <NUM> corresponding to different frequencies. For example, the frequency-domain representation <NUM> shows a peak <NUM> at a frequency. In other embodiments, peaks may occur at different frequencies and/or may have different amplitudes in the frequency-domain representation <NUM>.

The procedure <NUM> may further include normalizing the heart sounds in <NUM>. Normalizing the heart sounds can include determining an amount of attenuation of one of the heart sounds and utilizing the amount of attenuation to modify one or more of the heart sounds. In other embodiments, normalizing the heart sounds can include determining amounts of attenuation of a portion of the heart sounds and utilizing the amounts of attenuation to modify one or more of the heart sounds. The modification of the one or more heart sounds may comprise amplifying the one or more heart sounds, attenuating the one or more heart sounds, or amplifying a portion of the one or more heart sounds and attenuating another portion of the one or more heart sounds. The amounts of attenuation may be caused by improper application of sound sensors (such as incorrect positioning of the sound sensors and/or the sound sensors not be placed air-tight against the skin of the subject), and/or other forms of imperfections that can cause audio coupling imperfections between a body of a subject and a sensor used to measure heart sounds in some instances.

The heart sound or heart sounds utilized for determining the amount of attenuation may be predefined or may be indicated by a user. For example, one or more captures of the S1 heart sound or one or more captures of the S2 heart sound may be utilized for determining the amount of attenuation or the amounts of attenuation in some embodiments, where amplitudes of the S1 heart sound and the S2 heart sound could be uniform across multiple cardiac cycles in most instances. In some embodiments, a user may be presented with a choice between utilizing one or more captures of the S1 heart sound or one or more captures of the S2 heart sound and may indicate which of the captures of the S1 heart sound or the captures of the S2 heart sound.

In some embodiments, the heart sound or heart sounds utilized for determining the amount of attenuation may be selected based on the heart sound or heart sound utilized for determining the amount of attenuation being expected to be negatively correlated with the heart sound or heart sounds to be modified. For example, the heart sound or heart sounds utilized for determining the amount of attenuation may be expected to remain constant while the heart sound or heart sounds to be modified may change, or the heart sound or heart sounds utilized for determining the amount of attenuation may be expected to change in a direction opposite to the direction of the heart sound or heart sounds to be modified may be expected to change in instances where the heart sound or heart sounds to be modified change. Selecting the heart sound or heart sounds to be negatively correlated with the heart sound or heart sounds to be modified may allow for a coupling factor to be eliminated and the heart sound or hearts to be modified without displaying coupling effects. The captures of the S1 heart sound, the S2 heart sound, the S3 heart sound, and/or the S4 heart sound can be modified based on the determined amount of attenuation or the amounts of attenuation.

<FIG> illustrates an example procedure <NUM> for determining an amount of attenuation, according to embodiments herein. The procedure <NUM> may be performed as part of normalizing heart sounds in <NUM> (<FIG>). The procedure <NUM> may include comparing a capture <NUM> of an S1 heart sound with a control <NUM> for the S1 heart sound to determine an amount of attenuation. In particular, a frequency-domain representation of the capture <NUM> of the S1 heart sound can be compared with the control <NUM> for the S1 heart sound to determine the amount of attenuation. In the illustrated instance, the S1 heart sound may be the predetermined heart sound for determining the amount of attenuation or an indication that the S1 heart sound should be utilized for determining the amount of attenuation. In other instances, other heart sounds may be the predetermined heart sound or an indication that the other heart sounds should be utilized for determining the amount of attenuation, such as the S2 heart sound may be utilized in other instances.

The capture <NUM> of the S1 heart sound may have been produced via the decomposition in <NUM> and the spectral analysis in <NUM>. The capture <NUM> of the S1 heart sound may have been extracted from the electrical signal <NUM> (<FIG>). In particular, the capture <NUM> of the S1 heart sound may be the frequency-domain representation <NUM> (<FIG>) of the S1 heart sound in the illustrated instance.

The control <NUM> may be another frequency-domain representation of an S1 heart sound. The control <NUM> may have been captured during an initialization cycle, may have been captured during a previous test cycle, or may be generated by averaging multiple captures captured during an initialization cycle and/or previous test cycles. The control <NUM> may be captured in the presence of an authorized user (such as a health care provider) to assure that the frequency-domain representation is properly captured by a heart sound capture system. In some embodiments, controls may be captured for other heart sounds during the initialization cycle, may have been captured during the previous test cycle, or may be generated by averaging multiple captures captured during the initialization cycle and/or the previous test cycles. For example, controls may be captured for an S2 heart sound, an S3 heart sound, and/or an S4 heart sound in addition to the control for the S1 heart sound. The controls for the other heart sounds may be generated utilizing the heart sounds from the same cardiac cycle or cardiac cycles that were utilized for generating the S1 heart sound.

The procedure <NUM> may include comparing the capture <NUM> of the S1 heart sound to the control <NUM> for the S1 heart sound to determine an amount of attenuation. For example, one or more peaks, an average amplitude, a root mean square value, or other measurement of amplitude of the control <NUM> for the S1 heart sound can be compared with the corresponding measurement of the capture <NUM> of the S1 heart sound. In the illustrated instance, a first peak <NUM> of the control <NUM> occurring at a first frequency is compared with a first peak <NUM> of the capture <NUM> occurring at the first frequency to determine an amount of attenuation <NUM> at the first frequency. Further, a second peak <NUM> of the control <NUM> occurring at a second frequency is compared with a second peak <NUM> of the capture <NUM> occurring at the second frequency to determine an amount of attenuation <NUM> at the second frequency. As can be seen, the amount of attenuation <NUM> at the first frequency is greater than the amount of attenuation <NUM> at the second frequency, where the first frequency is lower than the second frequency. In other embodiments, one or more amounts of attenuation may be determined in the procedure <NUM> where each amount of attenuation can correspond to a corresponding frequency range. The determined amount or amounts of attenuation can be utilized for determining frequency-dependent amounts of modification for modifying the captures of heart sounds. In the illustrated instance, the capture <NUM> of the S1 heart sound is attenuated as compared to the control <NUM> to define the amount of attenuation <NUM>. In other instances, the control <NUM> may be attenuated as compared to the capture <NUM> of the S1 heart sound to define the amount of attenuation <NUM>.

<FIG> illustrates an example procedure <NUM> for modifying a capture of a heart sound, according to embodiments herein. A portion of the procedure <NUM> may be performed as part of the normalizing of the heart sounds in <NUM>. The procedure <NUM> may include modifying a capture <NUM> of an S4 heart sound to produce a normalized representation <NUM> of the S4 heart sound. In particular, a frequency-domain representation of the capture <NUM> of the S4 heart sound can be amplified to produce the normalized representation <NUM> of the S4 heart sound in the illustrated instance. In other instances, the frequency-domain representation of the capture <NUM> of the S4 heart sound can be attenuated to produce the normalized representation <NUM> of the S4 heart sound.

The capture <NUM> of the S4 heart sound may have been produced via the decomposition in <NUM> and the spectral analysis in <NUM>. The capture <NUM> of the S4 heart sound may have been extracted from the electrical signal <NUM> (<FIG>). In particular, the capture <NUM> of the S4 heart sound may be the frequency-domain representation <NUM> (<FIG>) of the S4 heart sound in the illustrated instance. While the modification of the capture <NUM> of the heart sound is illustrated in the instance, it should be understood that illustrated instance is merely an example and the modification procedure described can be applied to other captures and other heart sounds.

The capture <NUM> of the S4 heart sound may be modified to produce the normalized representation <NUM> of the S4 heart sound. The amount of modification of the capture <NUM> of the S4 heart sound to produce the normalized representation <NUM> of the S4 heart sound may be determined based on the amount of attenuation of another heart sound. For example, the amount of modification can be determined based on the determined amounts of attenuation between the capture <NUM> (<FIG>) of the S1 heart sound and the control <NUM> (<FIG>) for the S1 heart sound. Further, whether the modification is amplification of the capture <NUM> or an attenuation of the capture <NUM> may be determined based on whether the capture <NUM> is attenuated as compared to the control <NUM> or the control <NUM> is attenuated as compared to the capture <NUM>. For example, if the control <NUM> was captured in a state that resulted in an attenuated signal and if the source of attenuation is reduced or is no longer present when the capture <NUM> was made, the modification would be an attenuation of the capture <NUM> to maintain a consistent trend. Similarly, if the control <NUM> was captured in a state with no attenuation and if the source of attenuation is increased when the capture <NUM> was made, the modification would be an amplification of the capture <NUM> to maintain a consistent trend.

The amount of modification can be frequency-dependent where the amount of modification changes based on the different frequencies within the capture <NUM> of the S4 heart sound. In some embodiments, an equation can be applied to the amounts of attenuation to determine the amount of modification for each of the frequencies within the capture <NUM> of the S4 heart sound. In other embodiments, amounts of attenuation can be determined in procedure <NUM> (<FIG>) for each of the frequencies within the capture <NUM> of the S4 heart sound, where the amounts of modification can be utilized for determining the amount of modification for each of the corresponding frequencies.

As can be seen, a first peak <NUM> of the capture <NUM> is modified by a first amount of modification <NUM> to produce a first peak <NUM> of the normalized representation <NUM>. Further, a second peak <NUM> of the capture <NUM> is modified by a second amount of modification <NUM> to produce a second peak <NUM> of the normalized representation <NUM>. The first amount of modification <NUM> and the second amount of modification <NUM> may have been determined based on the amount of attenuation <NUM> (<FIG>) and the amount of attenuation <NUM> (<FIG>) in the illustrated instance. The first amount of modification <NUM> can be greater than the second amount of modification <NUM> based on the difference in frequency being modified. In particular, the first amount of modification <NUM> may be greater than the second amount of modification <NUM> based on the first amount of modification <NUM> modifying a first frequency that is lower than a second frequency being modified by the second amount of modification <NUM>. The amounts of modification being applied to the capture <NUM> can have particular amounts of modification for each frequency range, where each of the frequency ranges can include a single frequency or a range of frequencies.

The procedure <NUM> may include performing inverse spectral analysis in <NUM>. In particular, inverse spectral analysis may be performed on the normalized representations of the heart sounds produced by the normalization of the heart sounds in <NUM>. The inverse spectral analysis may include performing an inverse Fourier transform on the normalized representations of the heart sounds. The inverse spectral analysis may produce time-domain representations of the normalized representations of the heart sounds. The time-domain representations may be representations of the heart sounds without attenuation of the heart sounds that can cause improper analysis of the heart sounds. Accordingly, the time-domain representations generated with the normalized representations of the heart sounds can be utilized for analysis of the subject's heart sounds without concerns that the attenuation of the heart sounds could cause improper results of the analysis of the heart sounds.

<FIG> further illustrates an example of the performance of inverse spectral analysis in <NUM>. In particular, the normalized representation <NUM> of the S4 heart sound is shown with inverse spectral analysis performed to produce a time-domain representation <NUM> of the S4 heart sound. The time-domain representation <NUM> may be produced by applying an inverse Fourier transform to the normalized representation <NUM> of the S4 heart sound. The time-domain representation <NUM> of the S4 heart sound may be utilized for analysis of the captured S4 heart sound without concerns that attenuation that may be caused by the sound sensors being improperly applied. While inverse spectral analysis is illustrated being performed on a capture of an S4 heart sound, it should be understood that that the inverse spectral analysis may be performed on captures of any heart sounds, include S1 heart sounds, S2 heart sounds, S3 heart sounds, and S4 heart sounds.

In some embodiments, the modification of a capture of a heart sound may include determining whether the capture of the heart sound to be modified and the capture of the heart sound being utilized for determining the amount of attenuation are expected to be negatively correlated. <FIG> illustrates an example of performance of a modification of a capture of a heart sound that is negatively correlated, according to embodiments herein.

Determining whether a heart sound being modified and a heart sound being utilized for determining the amount of attenuation are positively or negatively correlated may be based on the relationship between each of the heart sounds and the corresponding controls. For example, the heart sound being modified and the heart sound being utilized for determining the amount of attenuation may be determined to be positively correlated if both of the heart sounds are approximately (within <NUM>%) equal to the corresponding controls or both of the heart sounds differ from the corresponding controls in the same direction and approximately (within <NUM>%) a same amount. The heart sound being modified and the heart sound being utilized for determining the amount of attenuation may be determined to be negatively correlated if the heart sound being utilized for determining the amount of attenuation remains approximately (within <NUM>%) equal to the corresponding control while the heart sound being modified varies from the corresponding control or the heart sound being utilized for determining the amount of attenuation varies from the corresponding control in one direction and the heart sound being modified varies from the corresponding control in the opposite direction.

In the illustrated embodiment, a capture <NUM> of an S1 heart sound is compared with a control <NUM> for the S1 heart sound to determine an amount of attenuation. In particular, a first peak <NUM> of the control <NUM> is compared with a first peak <NUM> of the capture <NUM>. The comparison determines that the first peak <NUM> of the capture <NUM> is attenuated to be below the first peak <NUM> of the control <NUM>, where a first amount of attenuation <NUM> of the capture <NUM> is determined based on the comparison. A second peak <NUM> of the control <NUM> is compared with a second peak <NUM> of the capture <NUM>. The comparison determines that the second peak <NUM> of the capture is attenuated to be below the second peak <NUM> of the control <NUM>, where a second amount of attenuation <NUM> of the capture <NUM> is determined based on the comparison.

Further, a capture <NUM> of an S3 heart sound is compared with a control <NUM> for the S3 heart sound. The comparison determines that a peak <NUM> of the capture <NUM> has increased as compared to a peak <NUM> of the control <NUM>. In particular, the peak <NUM> of the capture <NUM> may have an increase <NUM> over the peak <NUM> of the control <NUM>. Accordingly, it can be determined that the capture <NUM> of the S3 heart sound (i.e., the capture to be modified) has changed from the control <NUM> by being increased while the capture <NUM> of the S1 heart sound (i.e., the capture being utilized for determining the amount of attenuation) has changed from the control <NUM> by being decreased, thereby the capture <NUM> changing in the opposite direction as compared to the direction of change of the capture <NUM>. Accordingly, the capture <NUM> of the S3 heart sound and the capture <NUM> of the S1 heart sound are determined to be negatively correlated in the illustrated instance.

In instances where the capture to be modified and the capture being utilized for determining the amount of attenuation are determined to be negatively correlated, the changes in the capture to be modified may be determined to be due to change in coupling and the capture to be modified may be modified to eliminate coupling effects. In some instances where the capture to be modified and the capture being utilized for determining the amount of attenuation are determined not to be negatively correlated, the changes in the capture to be modified may be determined to be due to changes in the capture to be modified separate rather than changes due to coupling.

<FIG> illustrates an example system <NUM> that may implement the procedure <NUM> of <FIG>, according to embodiments herein. For example, the system <NUM> may capture heart sounds and normalize the captured heart sounds via the procedure <NUM>.

The system <NUM> may include one or more sound sensors <NUM>. The sound sensors <NUM> may be placed on a subject and may capture heart sounds of the subject. In particular, the sound sensors <NUM> may detect the heart sounds of the subject and generate an electrical signal that represents the detected heart sounds. In some embodiments, the sound sensors <NUM> may comprise electronic stethoscope, a piezoelectric sensor, an accelerometer, a microphone, any other sensor that can detect sounds and/or vibrations and generate an electrical signal that represents the detected sounds and/or vibrations, or some combination thereof.

The system <NUM> may further include a device <NUM>. The device <NUM> may be coupled to the sound sensors <NUM> and may receive the captured heart sounds from the sound sensors <NUM>.

The device <NUM> may include a memory device <NUM> in which the captured heart sounds may be stored after being received and for processing. In some embodiments, the memory device <NUM> may further include one or more instructions that, when executed by the device <NUM>, cause the device to perform the operations described herein. In other embodiments, the system <NUM> may include one or more other computer-readable media with the instructions stored thereon.

The device <NUM> may further include normalization circuitry <NUM>. The normalization circuitry <NUM> may include a processor <NUM>. The normalization circuitry <NUM> may perform the procedure <NUM> to normalize the captured heart sounds received from the sound sensors <NUM>. In particular, the normalization circuitry <NUM> may retrieve the captured heart sounds from the memory device <NUM> and normalize the heart sounds for further processing. In some embodiments, the normalization circuitry <NUM> may generate a control (such as the control <NUM> (<FIG>)) from one or more of the captured heart sounds and store the control in the memory device <NUM> to be utilized for normalization of the captured heart sound. The one or more captured heart sounds utilized for generating the control may have been captured during an initialization cycle of the system <NUM>. The normalization circuitry <NUM> may retrieve the control from the memory device <NUM> to utilize for normalization of heart sounds.

The device <NUM> may perform further processing of the normalized heart sounds. In other embodiments, the device <NUM> may be coupled to another device (such as a server) and may provide the normalized heart sounds to the other device. The other device may perform further processing with the heart sounds.

While the system <NUM> includes the sound sensors <NUM> coupled to the device <NUM> in the illustrated embodiment, it should be understood that the illustrated embodiment is an example embodiment and other embodiments may have other arrangements and/or additional elements. For example, the sound sensors <NUM> may be implemented within the device <NUM> in other embodiments.

While the captured heart sounds are disclosed as being stored on the memory device <NUM> of the system <NUM> in the illustrated embodiment, the captured heart sounds may be stored on one or more separate elements in other embodiments. For example, the captured heart sounds may be stored on a separate computing device or on one or more servers (such as the cloud) in other embodiments. The normalization circuitry <NUM> may retrieve the captured heart sounds from the one or more separate elements and perform the normalization on the retrieved heart sounds. In some embodiments, the device <NUM> may comprise a computing device or one or more servers (such as the cloud) located remote to the sound sensors <NUM> and may receive the captured heart sounds via a network for communication between another device coupled to the sound sensors <NUM> and the device <NUM>.

<FIG> illustrates an example procedure <NUM> for initialization and normalization by a heart sound capture system, according to embodiments herein. For example, the procedure <NUM> may be performed by the system <NUM>.

The procedure <NUM> may initiate in an initialization cycle <NUM>. The initialization cycle <NUM> may be performed in the presence of a care provider (such as a physician) to ensure that sound sensors of the system are properly placed on a subject during the initialization cycle <NUM>. In some embodiments, the system implementing the procedure <NUM> may require an authorization of a user as a care provider to enter the initialization cycle <NUM>, such as embodiments where a control is generated from heart sounds captured in the initialization cycle <NUM>.

The initialization cycle <NUM> may initiate by capturing one or more heart sounds in <NUM>. For example, one or more sound sensors (such as the sound sensors <NUM> (<FIG>)) may capture heart sounds of the subject and a device (such as the device <NUM> (<FIG>)) may store the captured heart sounds. In some embodiments, the capturing of the one or more heart sounds in <NUM> may be omitted. In these embodiments, the procedure <NUM> may initiate with <NUM>.

In <NUM>, a control may be generated from the one or more heart sounds captured in <NUM>. In some embodiments, a single heart sound from the one or more heart sounds may be stored as the control. In other embodiments, some portion of the one or more heart sounds may be averaged to produce a representation of a heart sound that may be stored as the control. In <NUM>, the control may be stored in a memory device (such as the memory device <NUM> (<FIG>)).

The procedure <NUM> may proceed with a test cycle <NUM>. The test cycle <NUM> may initiate by capturing one or more heart sounds in <NUM>. For example, one or more sound sensors may capture heart sounds of the subject and the device may store the captured heart sounds for analysis. In some embodiments, the one or more of the heart sounds captured in <NUM> may be utilized in <NUM> to generate the control.

In <NUM>, the heart sounds captured in <NUM> may be normalized. In particular, the heart sounds may be normalized by implementing the procedure <NUM> (<FIG>) for the heart sounds. The control produced in <NUM> may be utilized for the normalization of the heart sounds. The normalized heart sounds may be stored for further processing.

In some cases, the teachings of the present specification may be encoded into one or more tangible, non-transitory computer-readable mediums having stored thereon executable instructions that, when executed, instruct a programmable device (such as a processor or DSP) to perform the methods or functions disclosed herein. In cases where the teachings herein are embodied at least partly in a hardware device (such as an ASIC, IP block, or SoC), a non-transitory medium could include a hardware device hardware-programmed with logic to perform the methods or functions disclosed herein. The teachings could also be practiced in the form of Register Transfer Level (RTL) or other hardware description language such as VHDL or Verilog, which can be used to program a fabrication process to produce the hardware elements disclosed.

In example implementations, at least some portions of the processing activities outlined herein may also be implemented in software. In some embodiments, one or more of these features may be implemented in hardware provided external to the elements of the disclosed figures, or consolidated in any appropriate manner to achieve the intended functionality. The various components may include software (or reciprocating software) that can coordinate in order to achieve the operations as outlined herein. In still other embodiments, these elements may include any suitable algorithms, hardware, software, components, modules, interfaces, or objects that facilitate the operations thereof.

Any suitably-configured processor component can execute any type of instructions associated with the data to achieve the operations detailed herein. Any processor disclosed herein could transform an element or an article (for example, data) from one state or thing to another state or thing. In another example, some activities outlined herein may be implemented with fixed logic or programmable logic (for example, software and/or computer instructions executed by a processor) and the elements identified herein could be some type of a programmable processor, programmable digital logic (for example, an FPGA, an erasable programmable read only memory (EPROM), an electrically erasable programmable read only memory (EEPROM)), an ASIC that includes digital logic, software, code, electronic instructions, flash memory, optical disks, CD-ROMs, DVD ROMs, magnetic or optical cards, other types of machine-readable mediums suitable for storing electronic instructions, or any suitable combination thereof. In operation, processors may store information in any suitable type of non-transitory storage medium (for example, random access memory (RAM), read only memory (ROM), FPGA, EPROM, electrically erasable programmable ROM (EEPROM), etc.), software, hardware, or in any other suitable component, device, element, or object where appropriate and based on particular needs. Further, the information being tracked, sent, received, or stored in a processor could be provided in any database, register, table, cache, queue, control list, or storage structure, based on particular needs and implementations, all of which could be referenced in any suitable timeframe. Any of the memory items discussed herein should be construed as being encompassed within the broad term 'memory. ' Similarly, any of the potential processing elements, modules, and machines described herein should be construed as being encompassed within the broad term 'microprocessor' or 'processor. ' Furthermore, in various embodiments, the processors, memories, network cards, buses, storage devices, related peripherals, and other hardware elements described herein may be realized by a processor, memory, and other related devices configured by software or firmware to emulate or virtualize the functions of those hardware elements.

Claim 1:
One or more computer-readable media having instructions stored thereon, wherein the instructions, in response to execution by a device (<NUM>), cause the device to:
determine an amount of attenuation (<NUM>, <NUM>) between a capture (<NUM>) of a first heart sound and a control (<NUM>) for the first heart sound, wherein the capture (<NUM>) of the first heart sound is captured during a first test cycle (<NUM>), and wherein the capture (<NUM>) of the first heart sound is a first capture of the first heart sound;
modify a first portion (<NUM>) of a capture (<NUM>) of a second heart sound by a first amount (<NUM>), wherein the capture (<NUM>) of the second heart sound is captured during the first test cycle, wherein the first portion (<NUM>) corresponds to a first frequency range, and wherein the first amount (<NUM>) is determined based on the amount of attenuation;
modify a second portion (<NUM>) of the capture (<NUM>) of the second heart sound by a second amount (<NUM>), wherein the second portion (<NUM>) corresponds to a second frequency range, and wherein the second amount (<NUM>) is determined based on the amount of the attenuation;
characterized in that the instructions further cause the device to:
capture a second capture of the first heart sound during an initialization cycle, and wherein the initialization cycle occurs prior to the first test cycle; and
store the second capture of the first heart sound as the control for the first heart sound.