CN105877706A - Heart-sound enhancement method based on improved spectral subtraction - Google Patents
Heart-sound enhancement method based on improved spectral subtraction Download PDFInfo
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- CN105877706A CN105877706A CN201610202205.7A CN201610202205A CN105877706A CN 105877706 A CN105877706 A CN 105877706A CN 201610202205 A CN201610202205 A CN 201610202205A CN 105877706 A CN105877706 A CN 105877706A
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- cardiechema signals
- uproar
- band
- heart
- frequency
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
- A61B5/7203—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
- A61B5/7235—Details of waveform analysis
- A61B5/7253—Details of waveform analysis characterised by using transforms
- A61B5/7257—Details of waveform analysis characterised by using transforms using Fourier transforms
Abstract
The invention discloses a heart-sound enhancement method based on improved spectral subtraction, and mainly relates to the technical field of biologic signal processing. The method comprises the following steps: 1, extracting heart-sound envelope by utilizing Hilbert-Huang transform, segmenting based on the heart-sound envelope, and acquiring a complete a noisy heart-sound signal comprising a relaxation period and a contraction period; 2, carrying out FFT transformation on the extracted noisy heart-sound signal to obtain a frequency spectrum of the noisy heart-sound signal; 3, processing the frequency spectrum of the noisy heart-sound signal; 4, carrying out inverse Fourier transform on a frequency spectrum of the obtained pure heart-sound signal to obtain a pure heart-sound signal. The heart-sound enhancement method has the beneficial effects that the method adopts different noise spectrum power values, thus being capable of effectively removing noise and improving signal to noise ratio.
Description
Technical field
The present invention relates to bio signal processing technology field, a kind of based on the heart sound increasing improving spectrum-subtraction
Strong method.
Background technology
The detection of heart sound and analysis are to understand heart and the requisite means of one of blood vessel state, and it can
The diagnostic message in a large number with clinical meaning is provided.Along with the development of new technique, record the instrument of heart sound at present
There is the biggest improvement with method, but during record, the introducing of interference noise has remained inevitable
, such as heart sound transducer and the sassafras sound that rubs of skin, breathe noise, the interference signal of human body and grapher
Produced interference etc..These interfering noises produce unfavorable factor, if not making one to the heart sound waveform of record
Fixed process, can affect the result of heart sound analysis.
Traditional spectrum-subtraction thinks that noise is stationary noise, but is also likely to be non-stationary at whole heart sound section noise
Noise, simultaneously because the inhomogeneities of heart sound Energy distribution, if whole heart sound section is used identical noise
Spectral power value can not meet actual requirement.Therefore, heart sound to effectively be strengthened, it is necessary to the band noise heart
Tone signal has and clearly recognizes, thus grasps band and make an uproar the distribution character of noise in cardiechema signals, according to this characteristic
Noise power is the most gradually updated, reaches the purpose of Adaptive spectra subtraction speech enhan-cement.By in Fu in short-term
Leaf transformation analyzes cardiechema signals, finds that the frequency content of first heart sound s1 is concentrated mainly on 50Hz～150Hz
In the range of, and in the range of the frequency content of second heart sound s2 is concentrated mainly on 50Hz～200Hz, at 250Hz
～second small leak occurs in the range of 300Hz.
Summary of the invention
It is an object of the invention to provide a kind of heart sound Enhancement Method based on improvement spectrum-subtraction, it uses difference
Noise spectrum performance number, it is possible to effectively remove noise, it is possible to increase signal to noise ratio.
The present invention for achieving the above object, is achieved through the following technical solutions:
A kind of heart sound Enhancement Method based on improvement spectrum-subtraction, comprises the following steps:
Step 1, utilizes Hilbert-Huang transform to extract heart sound envelope, carries out segmentation based on heart sound envelope the most again,
Obtain one complete to make an uproar cardiechema signals y (n)=x (n)+u (n), wherein, x (n) containing relaxing period and Syst band
Representing pure cardiechema signals, u (n) represents noise signal；
Step 2, carries out FFT to the band cardiechema signals of making an uproar extracted, it is thus achieved that band is made an uproar the frequency spectrum of cardiechema signals
Yk=Xk+Uk, wherein, XkIt is the frequency spectrum of pure cardiechema signals, UkIt it is the frequency spectrum of noise signal；
Step 3, the frequency spectrum of cardiechema signals of making an uproar band processes,
When band make an uproar cardiechema signals frequency < during 50Hz, | Xk|2=| Yk|2,
When the frequency≤200Hz of cardiechema signals made an uproar by 50Hz≤band, | Xk|2=| Yk|2-αUk|2,
When 200Hz <band make an uproar cardiechema signals frequency < during 250Hz, | Xk|2=| Yk|2,
When the frequency≤300Hz of cardiechema signals made an uproar by 250Hz≤band, | Xk|2=| Yk|2-α|Uk|2,
When band is made an uproar the frequency of cardiechema signals > 300Hz time, | Xk|2=| Yk|2,
Wherein, 0≤α≤1；
Step 4, carries out inverse fourier transform to the frequency spectrum of the pure cardiechema signals obtained, it is thus achieved that pure heart sound is believed
Number.
In described step 3,
When the frequency≤200Hz of cardiechema signals made an uproar by 50Hz≤band, α=1,
When the frequency≤300Hz of cardiechema signals made an uproar by 250Hz≤band, α=0.8.
Contrast prior art, the beneficial effects of the present invention is:
1, the present invention utilizes Hilbert-Huang transform long heart sound can be carried out envelope extraction, it is possible to obtain
One section of complete cardiechema signals, it is possible to be easy to the analysis to cardiechema signals and process, heart sound that the band extracted is made an uproar
Signal carries out FFT, it is thus achieved that band is made an uproar the frequency spectrum of cardiechema signals, it is possible to clearly observe cardiechema signals
Spectrum distribution situation, modifies to traditional spectrum-subtraction, introduces α, uses different noise spectrum performance numbers,
Can effectively remove noise, improve signal to noise ratio.
2, in described step 3, when the frequency≤200Hz of cardiechema signals made an uproar by 50Hz≤band, α=1, when 250
Hz≤band make an uproar the frequency≤300Hz of cardiechema signals time, α=0.8, obtained the optimal value of α by great many of experiments
Scope, it is possible to obtain higher signal to noise ratio.
Accompanying drawing explanation
Accompanying drawing 1 is the flow chart of the present invention；
The band that accompanying drawing 2 is to be extracted is made an uproar cardiechema signals figure；
Accompanying drawing 3 is that the band extracted is made an uproar cardiechema signals figure；
Accompanying drawing 4 is that band is made an uproar the spectrogram of cardiechema signals；
Accompanying drawing 5 is the spectrogram of denoising cardiechema signals；
Accompanying drawing 6 is denoising cardiechema signals figure；
Accompanying drawing 7 is the contrast table of the present invention and tradition spectrum-subtraction acquired results.
Detailed description of the invention
Below in conjunction with specific embodiment, the present invention is expanded on further.Should be understood that these embodiments are only used for
The bright present invention rather than restriction the scope of the present invention.In addition, it is to be understood that in having read the present invention and having lectured
After appearance, the present invention can be made various changes or modifications by those skilled in the art, and these equivalent form of values are same
Fall within the application appended claims limited range.
Of the present invention is a kind of heart sound Enhancement Method based on improvement spectrum-subtraction, comprises the following steps:
Step 1, utilizes Hilbert-Huang transform to extract heart sound envelope, carries out segmentation based on heart sound envelope the most again,
Obtain one complete to make an uproar cardiechema signals y (n)=x (n)+u (n), wherein, x (n) containing relaxing period and Syst band
Representing pure cardiechema signals, u (n) represents noise signal.The band that accompanying drawing 2 is to be extracted is made an uproar cardiechema signals, its bag
Containing the heart sound that several are complete, utilize Hilbert-Huang transform, it is possible to extract one as shown in Figure 3
One complete makes an uproar cardiechema signals containing relaxing period and Syst band.
Step 2, carries out FFT to the band cardiechema signals of making an uproar extracted, it is thus achieved that band is made an uproar the frequency spectrum of cardiechema signals
Yk=Xk+Uk, wherein, XkIt is the frequency spectrum of pure cardiechema signals, UkIt it is the frequency spectrum of noise signal.To extraction
Band cardiechema signals of making an uproar carry out FFT, it is thus achieved that band as shown in Figure 4 is made an uproar the frequency spectrum of cardiechema signals, logical
Cross accompanying drawing 4 and can clearly observe that the spectrum distribution situation of cardiechema signals, at 50-200Hz, is dispersed with a large amount of
Information, here it is first heart sound s1 and part second heart sound s2；And also have few when 250-300Hz
Amount distribution is i.e. second small leak of s2.
Step 3, the frequency spectrum of cardiechema signals of making an uproar band processes,
When band make an uproar cardiechema signals frequency < during 50Hz, | Xk|2=| Yk|2,
When the frequency≤200Hz of cardiechema signals made an uproar by 50Hz≤band, | Xk|2=| Yk|2-α|Uk|2,
When 200Hz <band make an uproar cardiechema signals frequency < during 250Hz, | Xk|2=| Yk|2,
When the frequency≤300Hz of cardiechema signals made an uproar by 250Hz≤band, | Xk|2=| Yk|2-α|Uk|2,
When band is made an uproar the frequency of cardiechema signals > 300Hz time, | Xk|2=| Yk|2,
Wherein, 0≤α≤1.
Further, in described step 3,
When the frequency≤200Hz of cardiechema signals made an uproar by 50Hz≤band, α=1,
When the frequency≤300Hz of cardiechema signals made an uproar by 250Hz≤band, α=0.8.
Heart sound spectrogram after the denoising that step 3 obtains as shown in Figure 5, contrasts accompanying drawing 4,
During 50-200Hz, whole noise to be deducted, so amplitude substantially diminishes；And during 250-300Hz, deduct
Being a part for noise, but amplitude diminishes, change relatively is little, and at other frequency band, does not the most substantially have
Change.
Step 4, carries out inverse fourier transform to the frequency spectrum of the pure cardiechema signals obtained, it is thus achieved that pure heart sound is believed
Number.
Cardiechema signals after the denoising that step 4 obtains as shown in Figure 6, comparison accompanying drawing 3 it appeared that
Cardiechema signals after denoising, hence it is evident that smoothened.
The present invention utilizes Hilbert-Huang transform long heart sound can be carried out envelope extraction, it is possible to obtain one
The cardiechema signals that section is complete, it is possible to be easy to the analysis to cardiechema signals and process, heart sound letter that the band extracted is made an uproar
Number carry out FFT, it is thus achieved that band is made an uproar the frequency spectrum of cardiechema signals, it is possible to clearly observe the frequency of cardiechema signals
Spectral structure situation, modifies to traditional spectrum-subtraction, introduces α, uses different noise spectrum performance numbers, energy
Enough effectively remove noise, strengthen pure cardiechema signals, it is possible to increase signal to noise ratio.
Utilize MATLAB to emulate, pure cardiechema signals adds known noise signal and obtains a band and make an uproar the heart
Tone signal, then use traditional spectrum-subtraction and the present invention band respectively to above-mentioned generation make an uproar cardiechema signals enter place
Reason, obtain primary signal, by tradition spectrum-subtraction and the present invention obtained by signal to noise ratio compare, obtain as
Comparing result described in accompanying drawing 7, the present invention knowable to accompanying drawing 7 signal to noise ratio obtained is higher than traditional spectrum
The signal to noise ratio that subtraction is obtained.
Claims (2)
1. a heart sound Enhancement Method based on improvement spectrum-subtraction, is characterized in that: comprise the following steps:
Step 1, utilizes Hilbert-Huang transform to extract heart sound envelope, carries out segmentation based on heart sound envelope the most again,
Obtain one complete to make an uproar cardiechema signals y (n)=x (n)+u (n), wherein, x (n) containing relaxing period and Syst band
Representing pure cardiechema signals, u (n) represents noise signal；
Step 2, carries out FFT to the band cardiechema signals of making an uproar extracted, it is thus achieved that band is made an uproar the frequency spectrum of cardiechema signals
Yk=Xk+Uk, wherein, XkIt is the frequency spectrum of pure cardiechema signals, UkIt it is the frequency spectrum of noise signal；
Step 3, the frequency spectrum of cardiechema signals of making an uproar band processes,
When band make an uproar cardiechema signals frequency < during 50Hz, | Xk|2=| Yk|2,
When the frequency≤200Hz of cardiechema signals made an uproar by 50Hz≤band, | Xk|2=| Yk|2-α|Uk|2,
When 200Hz <band make an uproar cardiechema signals frequency < during 250Hz, | Xk|2=| Yk|2,
When the frequency≤300Hz of cardiechema signals made an uproar by 250Hz≤band, | Xk|2=| Yk|2-α|Uk|2,
When band is made an uproar the frequency of cardiechema signals > 300Hz time, | Xk|2=| Yk|2,
Wherein, 0≤α≤1；
Step 4, carries out inverse fourier transform to the frequency spectrum of the pure cardiechema signals obtained, it is thus achieved that pure heart sound is believed
Number.
A kind of heart sound Enhancement Method based on improvement spectrum-subtraction the most according to claim 1, is characterized in that:
In described step 3,
When the frequency≤200Hz of cardiechema signals made an uproar by 50Hz≤band, α=1,
When the frequency≤300Hz of cardiechema signals made an uproar by 250Hz≤band, α=0.8.
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Citations (7)
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|---|---|---|---|---|
| CN1373930A (en) * | 1999-09-07 | 2002-10-09 | 艾利森电话股份有限公司 | Digital filter design method and apparatus for noise suppression by spectral substraction |
| CN101972143A (en) * | 2010-11-16 | 2011-02-16 | 电子科技大学 | Blind source extraction-based atrial fibrillation monitoring method |
| CN103393435A (en) * | 2013-07-31 | 2013-11-20 | 深圳市理邦精密仪器股份有限公司 | Method and device for acquiring fetal heart sound signal envelope |
| CN103845079A (en) * | 2014-02-14 | 2014-06-11 | 广东工业大学 | Doppler fetal cardiac sound instantaneous heart rate detecting method based on blind separation |
| CN104778342A (en) * | 2014-01-14 | 2015-07-15 | 济南大学 | Heart sound characteristic extraction method based on wavelet singularity entropy |
| CN105266788A (en) * | 2015-11-11 | 2016-01-27 | 四川长虹电器股份有限公司 | Fetal heart sound separating method |
| CN105286845A (en) * | 2015-11-29 | 2016-02-03 | 浙江师范大学 | Movement noise elimination method suitable for wearable heart rate measurement device |
-
2016
- 2016-03-31 CN CN201610202205.7A patent/CN105877706A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1373930A (en) * | 1999-09-07 | 2002-10-09 | 艾利森电话股份有限公司 | Digital filter design method and apparatus for noise suppression by spectral substraction |
| CN101972143A (en) * | 2010-11-16 | 2011-02-16 | 电子科技大学 | Blind source extraction-based atrial fibrillation monitoring method |
| CN103393435A (en) * | 2013-07-31 | 2013-11-20 | 深圳市理邦精密仪器股份有限公司 | Method and device for acquiring fetal heart sound signal envelope |
| CN104778342A (en) * | 2014-01-14 | 2015-07-15 | 济南大学 | Heart sound characteristic extraction method based on wavelet singularity entropy |
| CN103845079A (en) * | 2014-02-14 | 2014-06-11 | 广东工业大学 | Doppler fetal cardiac sound instantaneous heart rate detecting method based on blind separation |
| CN105266788A (en) * | 2015-11-11 | 2016-01-27 | 四川长虹电器股份有限公司 | Fetal heart sound separating method |
| CN105286845A (en) * | 2015-11-29 | 2016-02-03 | 浙江师范大学 | Movement noise elimination method suitable for wearable heart rate measurement device |
Non-Patent Citations (1)
| Title |
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