Patent Issued for Sensitivity Calibration Method and Audio Device (USPTO 9374651)
By a News Reporter-Staff News Editor at Journal of Engineering -- HUAWEI TECHNOLOGIES CO., LTD. (Shenzhen, CN) has been issued patent number 9374651, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.
The patent's inventors are Jin, Jian (Shenzen, CN); Gao, Zhendong (Shanghai, CN).
This patent was filed on March 7, 2014 and was published online on June 21, 2016.
From the background information supplied by the inventors, news correspondents obtained the following quote: "In voice communication of a mobile phone, a main purpose of noise suppression is to suppress environmental noises, so that a wanted voice of a mobile phone user becomes clearer. The environmental noises are classified into stationary noises and non-stationary noises. Wanted voices are generally non-stationary.
"A noise suppression method includes: single-microphone (microphone) noise reduction and dual-microphone noise reduction. Single-microphone noise reduction suppresses stationary noises in environmental noises by detecting stationarity of voice signals captured by a microphone, but can hardly suppress non-stationary noises such as speech of people nearby. Dual-microphone noise reduction reduces noises by installing two microphones at specific positions in a mobile phone and using reception differences between voices and environmental noises of dual microphones. Dual-microphone noise reduction not only suppresses stationary noises desirably, but also suppresses non-stationary noises more effectively. Therefore, dual-microphone noise reduction is applied to more and more mobile phones.
"The reception differences between voices and environmental noises of dual microphones include: a phase difference, an energy difference, and so on, where the energy difference is an important characteristic that is used frequently. In normal use of a mobile phone, if a microphone close to a lower part of the mobile phone is referred to as a primary microphone, and the other microphone is referred to as a secondary microphone, the energy difference is represented as follows: Because the distance between the primary microphone and a wanted voice source is different from the distance between the secondary microphone and the wanted voice source, energy of wanted voices received by the primary microphone is higher than energy of wanted voices received by the secondary microphone; because the distance between the primary microphone and a noise source is basically the same as the distance between the secondary microphone and the noise source, energy of environmental noises received by the primary microphone is basically the same as energy of environmental noises received by the secondary microphone. The energy difference may be used to distinguish wanted voice signals from environmental noises. Specifically, if energy of a same voice signal captured by the primary microphone and the secondary microphone at the same time is basically the same, the voice signal may be considered as an environmental noise; otherwise, it is considered as a wanted voice signal; further, the purpose of noise reduction is achieved by removing the environmental noise.
"In a process of implementing dual-microphone noise reduction, it is found that the prior art has at least the following problems: When an energy difference between wanted voices and environmental noises received by dual microphones is used to distinguish wanted voices from environmental noises, it is required that sensitivity of the primary microphone should be strictly consistent with sensitivity of the secondary microphone. However, in an actual use process, aging, blockage, malfunction, and so on of the microphones may cause inconsistent sensitivity of the primary microphone and the secondary microphone, and further deteriorate the effect of dual-microphone noise reduction."
Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors' summary information for this patent: "Embodiments of the present invention provide a sensitivity calibration method and an audio device, where the audio device includes a primary capture module and a secondary capture module, and is used to calibrate sensitivity of the primary capture module and the secondary capture module, improve consistency of sensitivity between the two modules, and further improve a noise reduction effect.
"To achieve the foregoing objective, embodiments of the present invention adopt the following technical solutions:
"According to a first aspect, a sensitivity calibration method is provided, and applied to an audio device, where the audio device includes a primary capture module and a secondary capture module, and the method includes:
"determining whether a first signal captured in a current frame by the primary capture module is a circuit noise;
"when the first signal is not a circuit noise, if the first signal has a stationary noise characteristic, determining a first calibration gain according to the first signal and a second signal captured in the current frame by the secondary capture module; and
"calibrating the second signal according to the first calibration gain, so that sensitivity of the primary capture module is consistent with sensitivity of the secondary capture module.
"With reference to the first aspect, in a first possible implementation manner, the determining whether a first signal captured by the primary capture module is a circuit noise includes:
"obtaining a first characteristic value of the first signal, and comparing the first characteristic value with a preset circuit noise threshold, and if the first characteristic value is greater than the circuit noise threshold, determining that the first signal is not a circuit noise, or otherwise, determining that the first signal is a circuit noise, where the first characteristic value includes: an average amplitude value, or a square root of average energy.
"With reference to the first aspect or the first possible implementation manner of the first aspect, in a second possible implementation manner, the determining a first calibration gain according to the first signal and a second signal captured by the secondary capture module includes:
"determining the first calibration gain according to a ratio of the first characteristic value of the first signal to a second characteristic value of the second signal.
"With reference to the first aspect or the first possible implementation manner of the first aspect, in a third possible implementation manner, the determining a first calibration gain according to the first signal and a second signal captured by the secondary capture module includes:
"determining a preliminary calibration gain according to a ratio of the first characteristic value of the first signal to a second characteristic value of the second signal; and
"performing a smooth update on the determined preliminary calibration gain on a time axis according to a preset smoothing factor, and obtaining the first calibration gain.
"With reference to the third possible implementation manner of the first aspect, in a fourth possible implementation manner, the performing a smooth update on the determined preliminary calibration gain on a time axis according to a preset smoothing factor, and obtaining the first calibration gain include:
"determining the first calibration gain according to a proportional relationship between a second calibration gain and the preliminary calibration gain, where if the current frame is the first frame, the second calibration gain is a preset value, or if the current frame is not the first frame, the second calibration gain is a first calibration gain determined in a previous frame of the current frame.
"With reference to the fourth possible implementation manner of the first aspect, in a fifth possible implementation manner, before the determining the first calibration gain according to a proportional relationship between a second calibration gain and the preliminary calibration gain, the method further includes: setting a first calibration gain range according to the second calibration gain; and
"the determining the first calibration gain according to a proportional relationship between a second calibration gain and the preliminary calibration gain includes:
"obtaining an intermediate calibration gain according to the proportional relationship between the second calibration gain and the preliminary calibration gain; and
"if the intermediate calibration gain is within the first calibration gain range, use the intermediate calibration gain as the first calibration gain; or if the intermediate calibration gain is beyond the first calibration gain range, using a value, closest to the intermediate calibration gain, in the first calibration gain range as the first calibration gain.
"With reference to any one of the second possible implementation manner to the fifth possible implementation manner of the first aspect, in a sixth possible implementation manner, the calibrating the second signal according to the first calibration gain, so that sensitivity of the primary capture module is consistent with sensitivity of the secondary capture module includes:
"using a product of the second signal and the first calibration gain as the calibrated second signal.
"With reference to the first aspect, in a seventh possible implementation manner, the method further includes:
"when the first signal is a circuit noise, or when the first signal is not a circuit noise and the first signal does not have a stationary noise characteristic, calibrating the second signal according to a second calibration gain, where if the current frame is the first frame, the second calibration gain is a preset value, or if the current frame is not the first frame, the second calibration gain is a first calibration gain determined in a previous frame of the current frame.
"According to a second aspect, an audio device is provided, where the audio device includes a primary capture module and a secondary capture module, the primary capture module is configured to capture a first signal, the secondary capture module is configured to capture a second signal, and the audio device further includes:
"a circuit noise determining unit, configured to determine whether the first signal captured by the primary capture module is a circuit noise;
"a gain calculating unit, configured to determine a first calibration gain according to the first signal and the second signal captured by the secondary capture module when the first signal is not a circuit noise if the first signal has a stationary noise characteristic; and
"a first calibrating unit, configured to calibrate the second signal according to the first calibration gain, so that sensitivity of the primary capture module is consistent with sensitivity of the secondary capture module.
"With reference to the second aspect, in a first possible implementation manner, the circuit noise determining unit includes:
"an obtaining module, configured to obtain a first characteristic value of the first signal;
"a comparing module, configured to compare the first characteristic value with a preset circuit noise threshold, where the first characteristic value includes: an average amplitude value, or a square root of average energy; and
"a circuit noise determining module, configured to determine that the first signal is not a circuit noise if the first characteristic value is greater than the circuit noise threshold, or otherwise, determine that the first signal is a circuit noise.
"With reference to the second aspect or the first possible implementation manner of the second aspect, in a second possible implementation manner, the gain calculating unit specifically includes: determining the first calibration gain according to a ratio of the first characteristic value of the first signal to a second characteristic value of the second signal.
"With reference to the second aspect or the first possible implementation manner of the second aspect, in a third possible implementation manner, the gain calculating unit includes:
"a preliminary calibration gain calculating module, configured to determine a preliminary calibration gain according to a ratio of the first characteristic value of the first signal to a second characteristic value of the second signal; and
"a smooth updating module, configured to perform a smooth update on the determined preliminary calibration gain on a time axis according to a preset smoothing factor, and obtain the first calibration gain.
"With reference to the third possible implementation manner of the second aspect, in a fourth possible implementation manner, the smooth updating module is specifically configured to determine the first calibration gain according to a proportional relationship between a second calibration gain and the preliminary calibration gain, where if the current frame is the first frame, the second calibration gain is a preset value, or if the current frame is not the first frame, the second calibration gain is a first calibration gain determined in a previous frame of the current frame.
"With reference to the fourth possible implementation manner of the second aspect, in a fifth possible implementation manner, the gain calculating unit further includes a gain range setting module, configured to set a first calibration gain range according to the second calibration gain; where
"the gain updating module is specifically configured to: obtain an intermediate calibration gain according to the proportional relationship between the second calibration gain and the preliminary calibration gain; and
"if the intermediate calibration gain is within the first calibration gain range, use the intermediate calibration gain as the first calibration gain; or if the intermediate calibration gain is beyond the first calibration gain range, use a value, closest to the intermediate calibration gain, in the first calibration gain range as the first calibration gain.
"With reference to any one of the second possible implementation manner to the fifth possible implementation manner of the second aspect, in a sixth possible implementation manner, the first calibrating unit is specifically configured to use a product of the second signal and the first calibration gain as the calibrated second signal.
"With reference to the second aspect, in a seventh possible implementation manner, the device further includes:
"a second calibrating unit, configured to calibrate the second signal according to a second calibration gain when the first signal is a circuit noise, where if the current frame is the first frame, the second calibration gain is a preset value, or if the current frame is not the first frame, the second calibration gain is a first calibration gain determined in a previous frame of the current frame.
"With reference to the second aspect, in an eighth possible implementation manner, the device further includes:
"a third calibrating unit, configured to calibrate the second signal according to a second calibration gain when the first signal is not a circuit noise if the first signal does not have a stationary noise characteristic, where if the current frame is the first frame, the second calibration gain is a preset value, or if the current frame is not the first frame, the second calibration gain is a first calibration gain determined in a previous frame of the current frame.
"With the sensitivity calibration method and audio device provided by the embodiments of the present invention, a first calibration gain is determined according to an obtained first signal captured in a current frame by a primary capture module and an obtained second signal captured in the current frame by a secondary capture module, and the second signal is calibrated according to the first calibration gain, so that calibration is implemented for the secondary capture module, consistency of sensitivity between the primary capture module and the secondary capture module is improved, and further, a noise reduction effect is improved, and the problem of an undesired noise reduction effect caused by inconsistency of sensitivity between a primary capture module and a secondary capture module in the prior art is solved."
For the URL and additional information on this patent, see: Jin, Jian; Gao, Zhendong. Sensitivity Calibration Method and Audio Device. U.S. Patent Number 9374651, filed March 7, 2014, and published online on June 21, 2016. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=9374651.PN.&OS=PN/9374651RS=PN/9374651
Keywords for this news article include: HUAWEI TECHNOLOGIES CO. LTD..
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