Source: https://patents.google.com/patent/US20100296669
Timestamp: 2018-02-23 02:19:58
Document Index: 543786968

Matched Legal Cases: ['Application No. 61', 'Application No. 61', 'art 324', 'art 328', 'art 324', 'art 326', 'art 328', 'art 324', 'art 328', 'art 326', 'art 328', 'art 326', 'art 328', 'art 326', 'art 328']

US20100296669A1 - Apparatus for processing an audio signal and method thereof - Google Patents
US20100296669A1
US20100296669A1 US12719489 US71948910A US2010296669A1 US 20100296669 A1 US20100296669 A1 US 20100296669A1 US 12719489 US12719489 US 12719489 US 71948910 A US71948910 A US 71948910A US 2010296669 A1 US2010296669 A1 US 2010296669A1
US12719489
US8538043B2 (en )
A method of processing an audio signal is disclosed. The present invention includes receiving, by an audio processing apparatus, an input signal; receiving user gain input; generating a linear gain factor and a non-linear gain factor using the user gain input; modifying the non-linear gain factor using absolute threshold of hearing and power of the input signal to generate a modified non-linear gain factor; and, applying the linear gain factor and the modified non-linear gain factor to the audio signal.
This application claims the benefit of U.S. Provisional Application No. 61/158,388 filed on Mar. 8, 2009 and U.S. Provisional Application No. 61/164,459, filed on Mar. 29, 2009, which are hereby incorporated by reference.
According to the present invention, terminologies not disclosed in this specification can be construed as the following meanings and concepts matching the technical idea of the present invention. Specifically, ‘information’ in this disclosure is the terminology that generally includes values, parameters, coefficients, elements and the like and its meaning can be construed as different occasionally, by which the present invention is non-limited.
G 1  [ k , m ] = g 1 2  max  ( P S  [ k , m ] - P H  [ m ] , 0 ) + P H  [ m ] P S  [ k , m ] [ Formula   3 ]
In Formula 3, the G1[k, m] indicates a modified non-linear gain, the PH[m] indicates an absolute hearing threshold in a subband power domain, the g1 indicates a non-linear gain, the Ps[k, m] indicates a subband power of an input signal, the k indicates a time index, and the m indicates a frequency index.
Meanwhile, FIG. 3 shows the example of the absolute hearing threshold, while FIG. 4 shows the example of the absolute hearing threshold in the subband power domain. Particularly, FIG. 3 shows one example of the absolute hearing threshold according to each sound pressure level (SPL) [dB] per frequency. In this case, the sound pressure level is a pressure of sound by logarithm unit with reference to a specific pressure (e.g., 20 micro Pascal) and its unit is decibel. Occasionally, sound can be represented as sound intensity. Besides, a hearing sense actually perceived by a human for each sound pressure level is called sound loudness (unit: phon). And, an absolute hearing threshold indicates a minimum sound pressure level (SPL) that can be heard on each frequency. The minimum sound pressure level can correspond to a case that loudness is 3 phons. And, FIG. 3 shows one example of the absolute hearing threshold. Referring to FIG. 3, it can be observed that a sound pressure level corresponding to a hearing threshold is relatively high on a high frequency band (e.g., over 104 Hz) or a low frequency band (e.g., 0˜102 Hz). Hence, as mentioned in the foregoing description, when a volume is linearly adjusted, if the volume is adjusted into a low level, the intensity of the signal may fall into a level equal to or smaller than an audible frequency. In particular, if the volume is linearly adjusted into a low level, it may cause a problem that a human is unable to hear a signal on a high or low frequency band. The present invention intends to control a volume of a signal using a gain adaptive per frequency band.
Yet, the absolute hearing threshold represented as the sound pressure level per frequency band can be transformed into a subband power domain (or a power spectral domain). In case that the absolute hearing threshold is transformed into the subband power domain, a specific electric to acoustic power transfer function and approximate estimation of listening position can be explicitly or implicitly taken into consideration. In particular, when the absolute hearing threshold is transformed into a power domain from dB, if it is additionally scaled, a power spectral value approximately corresponds to a sound pressure level. One example of an absolute hearing threshold PH[m] transformed into a subband power domain is shown in FIG. 4. Since this algorithm puts limitation on a size of the absolute hearing threshold, it is advantageous in that the threshold is prevented from being exceeded on a very low or high frequency. If this limit value PH — μm is set higher than a minimum value of the absolute hearing threshold PH[m] by 20 dB at least, it can be represented as a dotted line part shown in FIG. 4.
Referring now to Formula 3, the g1 is the formerly defined non-linear gain. And, a max function is provided to prevent a subband power value of the input signal from becoming smaller than a value of the absolute hearing threshold (i.e., ‘PS[k, m]-PH[m]’ is prevented from becoming negative.). If the non-linear gain g1 is set to 0, G1[k, m] becomes a value that is not 1. If the non-linear gain g1 is set to 1, the G1[k, m] becomes 1.
If the user gain g is equal to or greater than the high reference value ghigh [‘No’ in the step S130], the comparing part 324A delivers the user gain g to the linear gain generating part 328A only. If the user gain g is equal to or greater than the high reference value ghigh [‘No’ in the step S130], the comparing part 324A delivers at least one of the high reference value ghigh and the low reference value glow to each of the non-linear gain generating part 326A and the linear gain generating part 328A as well as the user gain g.
As mentioned in the foregoing description, if the user gain g is equal to or greater than the high reference value ghigh [‘No’ in the step S130] [‘Interval 3’ in FIG. 7], the comparing part 324A delivers the user gain g to the linear gain generating part 328A only. Hence, the non-linear gain generating part 326A sets the non-linear gain g1 to 1 [S170], while the linear gain generating part 328A sets the linear gain g2 equal to the user gain g (g2=g) [S175].
On the contrary, if the user gain g is smaller than the high reference value ghigh and is also equal to or greater than the low reference value glow [‘No’ in the step S140] [‘Interval 2’ in FIG. 7], the non-linear gain generating part 326A generates the non-linear gain g1 using the user gain and the high reference value ghigh [S160], while the linear gain generating part 328A generates the linear gain g2 using the high reference value ghigh [S165].
Besides, if the user gain g is smaller than the low reference value glow [‘yes’ in the step S140] [‘interval 1’ in FIG. 7], the non-linear gain generating part 326A generates the non-linear gain g1 using the high reference value ghigh and the low reference value glow [S150], while the linear gain generating part 328A generates the linear gain g2 using the user gain g, the high reference value ghigh and the low reference value glow [S155].
If glow<g<ghigh , g 1=g/ghigh, g2=ghigh
If g<glow , g 1 =g low /g high , g 2 =g·g high /g low [Formula 5]
Meanwhile, FIG. 7 is a diagram for per-interval variations of linear and non-linear gains. In a first case (‘interval 3’ in FIG. 7) of Formula 5, a non-linear gain is set to 1 and a user gain is handled as a linear gain. Hence, a volume control is linearly performed in this interval. In a second case (‘interval 2’ in FIG. 7) of Formula 5, a non-linear gain increases according to a size of a user gain g, whereas a linear gain is set to a constant (e.g., ghigh). Hence, it can be observed that a non-linear volume control is dominant in this interval. In a third case (‘interval 1’ in FIG. 7) of Formula 5, a non-linear gain is set to a constant (e.g., glow/ghigh) and a user gain is able to increase according to a size of a user gain g. Hence, like the interval 3, it can be observed that a linear volume control is dominant in this interval.
The non-linear gain factor g1 and the linear gain factor g2 are generated based on whether the user gain input is lower or higher than at least one of a low reference value and a high reference value. In particular, when the user gain input is lower than a low reference value (in a third case (‘interval 1’ in FIG. 7) of Formula 5), the non-linear gain factor is generated as a fixed value, and the linear gain factor is generated using the user gain input. When the user gain input is equal to or higher than a low reference value (in a second case (‘interval 2’ in FIG. 7) of Formula 5), the non-linear gain factor is generated using the user gain input and the linear gain factor is generated as a fixed value. The fixed value is determined according to the low reference value and a high reference value. When the user gain input is equal or higher than a high reference value (in a first case (‘interval 3’ in FIG. 7) of Formula 5), the non-linear gain factor may be equal to one and the linear gain factor may be equal to the user gain input.
Referring to FIG. 9 and FIG. 10, if the user gain g is equal to or greater than the low reference value glow [‘No’ in the step S240 in FIG. 9] [‘interval 2’ in FIG. 10], the non-linear gain g1 is set equal to the user gain g [S260] and the linear gain g2 is set to 0 [S265].
On the contrary, if the user gain g is smaller than the low reference value glow [‘Yes’ in the step S240 shown in FIG. 9] [‘interval 1’ in FIG. 10], the non-linear gain the non-linear gain glow is generated using the low reference value glow [S250] and the linear gain g2 is generated using the user gain g and the low reference value glow [S225].
In a first case of Formula 6 (‘interval 2’ in FIG. 10), a user gain is a non-linear gain and a linear gain is set to 1. Hence, a volume control is non-linearly performed in this interval. In a second case of Formula 6 (‘interval 1’ in FIG. 10), a non-linear gain is a constant (e.g., glow) and a linear gain is able to increase according to a size of a user gain g. Hence, it can be observed that a linear control is relatively dominant in this interval.
The non-linear gain factor g1 and the linear gain factor g2 are generated based on whether the user gain input is lower or higher than at least one of a low reference value. In particular, when the user gain input is lower than a low reference value (in a second case (‘interval 1’ in FIG. 7) of Formula 6), the non-linear gain factor g1 is generated as a fixed value, and the linear gain factor g2 is generated using the user gain input. When the user gain input is equal to or higher than a low reference value (in a first case (‘interval 2’ in FIG. 7) of Formula 6), the non-linear gain factor is generated using the user gain input and the linear gain factor is generated as a fixed value. The fixed value is determined according to the low reference value. When the user gain input is equal or higher than a low reference value (in a first case (‘interval 2’ in FIG. 7) of Formula 6), the non-linear gain factor may be equal to the user gain input and the linear gain factor may be equal to one.
B  ( t ) = min  ( max  ( p  ( t ) - p min , 0 ) p max - p min , 1.0 ) [ Formula   8 ]
In Formula 8, the B(t) indicates an indicator function, the Pmax indicates a maximum power, and the Pmin indicates a minimum power.
receiving, by an audio processing apparatus, an input signal;
receiving user gain input;
generating a linear gain factor and a non-linear gain factor using the user gain input;
modifying the non-linear gain factor using absolute threshold of hearing and power of the input signal to generate a modified non-linear gain factor; and,
applying the linear gain factor and the modified non-linear gain factor to the audio signal.
the non-linear gain factor and the linear gain factor are generated based on whether the user gain input is lower or higher than at least one of a low reference value and a high reference value.
when the user gain input is lower than a low reference value, the non-linear gain factor is generated as a fixed value, and the linear gain factor is generated using the user gain input, and,
when the user gain input is equal to or higher than the low reference value, the non-linear gain factor is generated using the user gain input and the linear gain factor is generated as a fixed value.
the fixed value is determined according to at least one of the low reference value and a high reference value.
when the user gain input is equal to or higher than a high reference value, the non-linear gain factor is equal to one and the linear gain factor is equal to the user gain input.
when the user gain input is equal to or higher than a low reference value, the non-linear gain factor is equal to the user gain input and the linear gain factor is equal to one.
a receiving unit receiving an input signal;
a user gain receiving part receiving user gain input;
a gain splitting part generating a linear gain factor and a non-linear gain factor using the user gain input;
a non-linear gain modifying part modifying the non-linear gain factor using absolute threshold of hearing and power of the input signal to generate a modified non-linear gain factor; and,
a gain applying part applying the linear gain factor and the modified non-linear gain factor to the audio signal.
when the user gain input is equal to or higher than the low reference value, the non-linear gain factor is generated using the user gain input, and the linear gain factor is generated as a fixed value.
US12719489 2009-03-08 2010-03-08 Apparatus for processing an audio signal and method thereof Active 2032-02-02 US8538043B2 (en)
US12719489 US8538043B2 (en) 2009-03-08 2010-03-08 Apparatus for processing an audio signal and method thereof
US20100296669A1 true true US20100296669A1 (en) 2010-11-25
US8538043B2 US8538043B2 (en) 2013-09-17
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US12719388 Active 2031-11-17 US8515087B2 (en) 2009-03-08 2010-03-08 Apparatus for processing an audio signal and method thereof
US12719489 Active 2032-02-02 US8538043B2 (en) 2009-03-08 2010-03-08 Apparatus for processing an audio signal and method thereof
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US9112466B1 (en) * 2012-06-11 2015-08-18 Google Inc. Method for controlling volume using a rotating knob interface
US20100111339A1 (en) * 2008-10-31 2010-05-06 Zounds, Inc. System for managing feedback
WO2010104300A2 (en) 2010-09-16 application
US20100310085A1 (en) 2010-12-09 application
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US20100228368A1 (en) 2010-09-09 Apparatus for processing an audio signal and method thereof
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