WO2010005401A1 - Device and method for detection of breathing - Google Patents
Device and method for detection of breathing Download PDFInfo
- Publication number
- WO2010005401A1 WO2010005401A1 PCT/SI2009/000026 SI2009000026W WO2010005401A1 WO 2010005401 A1 WO2010005401 A1 WO 2010005401A1 SI 2009000026 W SI2009000026 W SI 2009000026W WO 2010005401 A1 WO2010005401 A1 WO 2010005401A1
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- WO
- WIPO (PCT)
- Prior art keywords
- microphones
- breathing
- measuring
- detection
- nostrils
- Prior art date
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B7/00—Instruments for auscultation
- A61B7/003—Detecting lung or respiration noise
Definitions
- the subject of the present invention is a device and method for detection of breathing, or more precisely an electric device detecting user's breathing by means of a personal computer, with which it is connected via sound card.
- Main characteristics of the invention are as follows: extremely rapid operation, operation in a noisy environment as well, completely nondisturbing use and price efficient configuration.
- the subject of the present patent application is a similar solution to that under number 3, yet better in that it can among others extremely efficiently eliminate environmental noise, which means that it detects breathing very well also in a noisy environment, and it also automatically adapts to breathing of various intensity or dynamics.
- the subject of the invention of the present patent application brings about improvements applicable in the following fields: rehabilitation of patients suffering from respiratory diseases (training system for patients suffering from chronic obstructive pulmonary disease or asthma), entertainment technology (interactive music, relaxation applications), alternative medicine (relaxation by way of subconscious regulation of breathing), polysomnography (monitoring/analysis of sleep and diagnosis of sleeping disorders), training systems for speakers, musicians, divers, pilots...
- Fig. 1 embodiment of a sound headphone with arranged semicircular arch, support plate and microphones
- Fig. 2 connection of microphones with a preamplifier system and personal computer
- Fig. 3 block diagramme of all conversions of magnitudes executed in a personal computer.
- the device consists of sound headphones represented by a head arch 5 and two individual earphones 6 and 6'.
- a rectangular plate 1 is fastened to said headphones via semicircular arch 2 and on said plate two measuring microphones 4 and 4' are embedded in a way that the latter are located in front of user's nostril ' s when used.
- two measuring microphones 4 and 4 r there are two reference microphones 3 and 3' arranged on the housing of said headphones.
- the headphones are located exactly above user's ears.
- Said measuring microphones 4, 4' and said reference microphones 3, 3' are led to a four-channel sound card integrated in a personal computer 8 through four preamplifier systems 71, 72, 73 and 74.
- the positioning of microphones in the above embodiment is implemented through sound headphones by added arch 2 and said plate 1.
- any other known fastening of microphones to desired positions i.e. in front of user's nostrils or on a location not less than 3 cm away from nostrils yet on the user's head, preferably symmetrically on the head, may be possible within the scope of the invention.
- Fastening may be implemented by an adequate support or even by known temporary sticking to skin.
- the embodiment further represents two measuring microphones 4 and 4' and two reference microphones 3 and 3'.
- An embodiment with at least one and mostly two measuring microphones 4, 4' in combination with at least one and mostly two reference microphones 3, 3' lies within the scope of the invention, of course, addition of signals of two microphones and calculation of their mean is not needed in this case.
- a further disclosure of the method describes all conversions of magnitudes executed in a personal computer. The magnitudes were captured and entered to a computer by way of the above device.
- a first step of the method is elimination of high-frequency content in all four channels, which is carried our by low-pass filters 91, 92, 93 and 94. The method of elimination of high-frequency content is not described in more detail, since it is not subject of the present invention.
- the next step of the method is calculation of average power of windows of 256 samples, which is implemented in four modules for the calculation of power 101, 102, 103 and 104. Calculation in each individual module is done by the following equation:
- n 256 (size of the window)
- the next step of the method is subtracting possible noise disturbances from the environment, which is performed as follows: first, by adding magnitudes of both reference microphones and by multiplying this sum by 0.5, the reference magnitude of noise intensity is determined. The resulting reference magnitude is then subtracted from the magnitudes of both measuring microphones, with which noise is subtracted from the measuring magnitudes.
- the next step is smoothing of the curve, which is done in module 11, where the system eliminates the unnecessary high-frequency content of the signal. This is implemented by simultaneous calculation of sliding mean.
- the equation for the calculation of an individual sample is as follows: JC; l ⁇ JC; i ⁇ i ⁇ JC i o ⁇ ⁇ JC - Q
- the next step of the method is determination of a triggering threshold for determination of exhalation, which is implemented in module 12.
- This step of the method sets a threshold in real time, at which an individual exhalation is detected. If said threshold is set too low, the system may detect too many exhalations (i.e. false exhalations as well), if it is set to high, the system may fail to detect some exhalation.
- the triggering threshold is determined in the following way: the system measures the maximum value of a magnitude, withholds it for a period of one half of a mean breath period and then decreases it linearly with time by the factor that is in inverse proportional dependence on the mean breath period.
- Pi >Pi- ⁇ > Pi- 2 >Pi- 3 are the last f our "breath periods" ("breath period” ⁇ measured time between two exhalations)
- a tolerance field in the order of 5% of the entire dynamic field may be applied, which does away with multiple triggerings, which occur due to high-frequency activity of the signal (i.e. when a magnitude would several times exceed the triggering threshold due to its high-frequency activity).
- the module for determining attributes 13 individual attributes needed for the generation of response are determined. These attributes are forwarded to the module for generating response 14, which forwards the response to user either via screen or loudspeakers.
- the device and method for detection of breathing solve a problem of configuration of such system for detection of breathing that is rapidly responsive, resistant to noise from the environment and self-adaptable to breathing with different dynamics or intensity.
- the system consists of a support, on which one or two measuring microphones and one or two reference microphones are fastened, said microphones being further connected to a personal computer via preamplifier system, in which computer digital processing of signals is executed. Measured magnitudes are first calculated to average intensities of windows of 256 samples, and then environmental noise is eliminated by subtracting mean power of reference signals from mean power of measuring signals.
- a threshold is determined, in which an individual exhalation is determined, which is defined by a function that determines the threshold in that it equalises it on every occurrence with the highest value of the magnitude of the processed signal of breathing; the latter is than withheld for a period of one half of a mean breath period and then decreased linearly in time by the factor, which is in inverse proportion to dependence on mean breath period.
- a hysteresis function should be applied or rather tolerance field in the order of 5% of the entire dynamic field, which does away with multiple triggerings, which occur due to high-frequency activity of the signal, i.e. when a magnitude would several times exceed the triggering threshold due to its high-frequency activity.
Abstract
The device and method for detection of breathing solve a problem of configuration of such system for detection of breathing that is rapidly responsive, resistant to noise from the environment and self-adaptable to breathing with different dynamics or intensity. The system of the embodiment consists of conventional headphones (5, 6, 6'), to which two measuring (4) and two reference (3) microphones are fastened, said microphones being further connected to a personal computer via preamplifier system, in which computer digital processing of signals is executed. Measured magnitudes are first calculated to average intensities of windows of 256 samples, and then environmental noise is eliminated by subtracting mean power of reference signals from mean power of measuring signals. Subsequently a threshold is determined, in which an individual exhalation is determined, which is defined by a function that determines the threshold in that it equalises it on every occurrence with the highest value of the magnitude of the processed signal of breathing; the latter is than withheld for a period of one half of a mean breath period and then decreased linearly in time by the factor, which is in inverse proportion to dependence on mean breath period. In defining an individual exhalation, i.e. when a signal reaches the triggering threshold, a hysteresis function should be applied or rather tolerance field in the order of 5% of the entire dynamic field, which does away with multiple triggerings, which occur due to high-frequency activity of the signal, i.e. when a magnitude would several times exceed the triggering threshold due to its high- fre uenc activit.
Description
Device and method for detection of breathing
The subject of the present invention is a device and method for detection of breathing, or more precisely an electric device detecting user's breathing by means of a personal computer, with which it is connected via sound card. Main characteristics of the invention are as follows: extremely rapid operation, operation in a noisy environment as well, completely nondisturbing use and price efficient configuration.
A technical problem solved by the present invention is a configuration of such system for detection of breathing that is:
1. Rapidly responsive (less than 1 ms)
2. Resistant to noise from the environment (up to intensity of 80 dB)
3. Self-adaptable for breathing of different dynamics.
Current solutions for "detection of breathing" are as follows:
1. Observation of a frequency spectre of light shining through exhaled air
2. Measurement of air temperature closely in front of nostrils
3. Microphone in front of nostrils or on chest or pharynx
4. "Respitrace sensor"- sensor measuring the volume of lungs
The subject of the present patent application is a similar solution to that under number 3, yet better in that it can among others extremely efficiently eliminate environmental noise, which means that it detects breathing very well also in a noisy environment, and it also automatically adapts to breathing of various intensity or dynamics.
The subject of the invention of the present patent application brings about improvements applicable in the following fields: rehabilitation of patients suffering from respiratory diseases (training system for patients suffering from chronic obstructive pulmonary disease or asthma), entertainment technology (interactive music, relaxation applications),
alternative medicine (relaxation by way of subconscious regulation of breathing), polysomnography (monitoring/analysis of sleep and diagnosis of sleeping disorders), training systems for speakers, musicians, divers, pilots...
The invention will be described by way of an embodiment and Figures, showing in:
Fig. 1 : embodiment of a sound headphone with arranged semicircular arch, support plate and microphones,
Fig. 2: connection of microphones with a preamplifier system and personal computer,
Fig. 3: block diagramme of all conversions of magnitudes executed in a personal computer.
In the embodiment from Fig. 1 the device consists of sound headphones represented by a head arch 5 and two individual earphones 6 and 6'. A rectangular plate 1 is fastened to said headphones via semicircular arch 2 and on said plate two measuring microphones 4 and 4' are embedded in a way that the latter are located in front of user's nostril's when used. Apart from the two measuring microphones 4 and 4r there are two reference microphones 3 and 3' arranged on the housing of said headphones. When in use, the headphones are located exactly above user's ears. Said measuring microphones 4, 4' and said reference microphones 3, 3' are led to a four-channel sound card integrated in a personal computer 8 through four preamplifier systems 71, 72, 73 and 74.
The positioning of microphones in the above embodiment is implemented through sound headphones by added arch 2 and said plate 1. However, any other known fastening of microphones to desired positions, i.e. in front of user's nostrils or on a location not less than 3 cm away from nostrils yet on the user's head, preferably symmetrically on the head, may be possible within the scope of the invention. Fastening may be implemented by an adequate support or even by known temporary sticking to skin. The embodiment further represents two measuring microphones 4 and 4' and two reference microphones 3 and 3'. An embodiment with at least one and mostly two measuring microphones 4, 4' in combination with at least one and mostly two reference microphones 3, 3' lies within the
scope of the invention, of course, addition of signals of two microphones and calculation of their mean is not needed in this case.
A further disclosure of the method describes all conversions of magnitudes executed in a personal computer. The magnitudes were captured and entered to a computer by way of the above device. A first step of the method is elimination of high-frequency content in all four channels, which is carried our by low-pass filters 91, 92, 93 and 94. The method of elimination of high-frequency content is not described in more detail, since it is not subject of the present invention. The next step of the method is calculation of average power of windows of 256 samples, which is implemented in four modules for the calculation of power 101, 102, 103 and 104. Calculation in each individual module is done by the following equation:
wherein: n = 256 (size of the window)
The next step of the method is subtracting possible noise disturbances from the environment, which is performed as follows: first, by adding magnitudes of both reference microphones and by multiplying this sum by 0.5, the reference magnitude of noise intensity is determined. The resulting reference magnitude is then subtracted from the magnitudes of both measuring microphones, with which noise is subtracted from the measuring magnitudes. The next step is smoothing of the curve, which is done in module 11, where the system eliminates the unnecessary high-frequency content of the signal. This is implemented by simultaneous calculation of sliding mean. The equation for the calculation of an individual sample is as follows:
JC; l~ JC; i ~ i ~ JC i o ι ~ JC - Q
4
The next step of the method is determination of a triggering threshold for determination of exhalation, which is implemented in module 12. This step of the method sets a threshold in real time, at which an individual exhalation is detected. If said threshold is set too low, the system may detect too many exhalations (i.e. false exhalations as well), if it is set to high, the system may fail to detect some exhalation. The triggering threshold is determined in the following way: the system measures the maximum value of a magnitude, withholds it for a period of one half of a mean breath period and then decreases it linearly with time by the factor that is in inverse proportional dependence on the mean breath period.
The equation determining the time of withholding triggering threshold is as follows:
Pi >Pi-ι > Pi-2 >Pi-3 are the last f our "breath periods" ("breath period" ~ measured time between two exhalations)
The equation determining the factor of linear decrease in the triggering threshold is as follows:
*
wherein: Pi-2>Pi-i are Me last four "breath periods" ("breath period" measured time between two exhalations)
In determining an individual exhalation (i.e. when a signal reaches the triggering threshold), a tolerance field in the order of 5% of the entire dynamic field may be applied, which does away with multiple triggerings, which occur due to high-frequency activity of the signal (i.e. when a magnitude would several times exceed the triggering threshold due to its high-frequency activity).
Further, in the module for determining attributes 13 individual attributes needed for the generation of response are determined. These attributes are forwarded to the module for generating response 14, which forwards the response to user either via screen or loudspeakers.
The device and method for detection of breathing solve a problem of configuration of such system for detection of breathing that is rapidly responsive, resistant to noise from the environment and self-adaptable to breathing with different dynamics or intensity. The system consists of a support, on which one or two measuring microphones and one or two reference microphones are fastened, said microphones being further connected to a personal computer via preamplifier system, in which computer digital processing of signals is executed. Measured magnitudes are first calculated to average intensities of windows of 256 samples, and then environmental noise is eliminated by subtracting mean power of reference signals from mean power of measuring signals. Subsequently a threshold is determined, in which an individual exhalation is determined, which is defined by a function that determines the threshold in that it equalises it on every occurrence with the highest value of the magnitude of the processed signal of breathing; the latter is than withheld for a period of one half of a mean breath period and then decreased linearly in time by the factor, which is in inverse proportion to dependence on mean breath period. In defining an individual exhalation, i.e. when a signal reaches the triggering threshold, a hysteresis function should be applied or rather tolerance field in the order of 5% of the entire dynamic field, which does away with multiple triggerings, which occur due to high-frequency activity of the signal, i.e. when a magnitude would several times exceed the triggering threshold due to its high-frequency activity.
Claims
1. Device for detection of breathing consisting of a support element, acoustic microphones, preamplifier system and a personal computer, characterised in that a rectangular plate (1) is fastened to headphones (5, 6, 6') via semicircular arch (2), and on said plate there are integrated two measuring microphones (4, 4') in a way that they are located in front of user's nostrils when said headphones are used, and apart from said measuring microphones (4, 4') two reference microphones (3, 3') are arranged on the housing of said headphones in a way that they are located exactly above user's ears when the headphones are used.
2. Device for detection of breathing, characterised in that it comprises at least one and mostly two measuring microphones (4, 4') and at least one and mostly two reference microphones (3, 3'), wherein at least one and mostly two measuring microphones (4, 4') are located in front of user's nostrils and at least one and mostly two reference microphones (3, 3') are located on the head, at a distance at least 3 cm from the nostrils, symmetrically on the head, wherein said measuring microphones (4, 4') capture sound signals in front of nostrils and said reference microphones (3, 3') sound signals from the environment.
3. Device as claimed in Claims 1 and 2, characterised in that said measuring microphones (4, 4') and said reference microphones (3, 3') are led to a personal computer (8) via preamplifier systems (71, 72, 73, 74).
4. Method for detection of breathing by way of capturing sound signals, characterised in that apart from two sound signals captured in front of the nostrils at least one and mostly two sound signals are captured at a distance at least 3 cm from the nostrils and are reference signals and their entire mean value is subtracted from average power of sound signals, wherein noise from the environment is eliminated from the measuring signal.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SI200800175A SI22830A (en) | 2008-07-09 | 2008-07-09 | Device and procedure for breathing detection |
| SIP-200800175 | 2008-07-09 | ||
| SI200900171A SI23068A (en) | 2009-06-24 | 2009-06-24 | Device and procedure for breathing detection |
| SIP-200900171 | 2009-06-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2010005401A1 true WO2010005401A1 (en) | 2010-01-14 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/SI2009/000026 WO2010005401A1 (en) | 2008-07-09 | 2009-07-01 | Device and method for detection of breathing |
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| Country | Link |
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| WO (1) | WO2010005401A1 (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4924876A (en) * | 1987-11-04 | 1990-05-15 | Peter Cameron | Nasal breath monitor |
| DE19508810A1 (en) * | 1995-03-06 | 1996-09-12 | Sita Daten Und Kommunikations | Microphone breathing rate sensor for biofeedback system |
| US20070003072A1 (en) * | 2005-06-29 | 2007-01-04 | Ward Russell C | Ambient noise canceling physiological acoustic monitoring system & method |
-
2009
- 2009-07-01 WO PCT/SI2009/000026 patent/WO2010005401A1/en active Application Filing
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4924876A (en) * | 1987-11-04 | 1990-05-15 | Peter Cameron | Nasal breath monitor |
| DE19508810A1 (en) * | 1995-03-06 | 1996-09-12 | Sita Daten Und Kommunikations | Microphone breathing rate sensor for biofeedback system |
| US20070003072A1 (en) * | 2005-06-29 | 2007-01-04 | Ward Russell C | Ambient noise canceling physiological acoustic monitoring system & method |
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