AUDIO REPRODUCTION METHOD AND APPARATUS WITH AUTO VOLUME CONTROL FUNCTION
An audio reproduction method and apparatus, in which an audio volume is automatically controlled based on audio energy and human auditory characteristics. The audio reproduction method includes splitting a reproduction audio signal into audio signals corresponding to a plurality of frequency bands, extracting audio energy for each of the frequency bands, and comparing the audio energy for each of the frequency bands with a predetermined threshold and controlling the volume of the audio signal corresponding to each of the frequency bands.
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This application claims the benefit of Korean Patent Application No. 10-2007-0010677, filed on Feb. 1, 2007, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present general inventive concept relates to an audio reproduction apparatus and method, and more particularly, to an audio reproduction apparatus and method, in which an audio volume can be automatically controlled based on audio energy and human auditory characteristics.
2. Description of the Related Art
Research on noise-induced hearing loss shows that hearing may be damaged by long-period exposure to noise of a higher level than a predetermined level. For this reason, various international industrial accident-related organizations establish noise exposure control regulations and use them as industrial accident-related standards.
As the number of users of portable devices and earphones (or headphones) increases, a more number of users complain of serious levels of hearing damage.
In this context, audio volume control apparatuses for protecting hearing have been developed.
U.S. 2003/0002688 A1, published on Jan. 2, 2003 and entitled “Volume Regulating and Monitoring System,” discloses a conventional technique related to a conventional audio volume control apparatus.
In the conventional audio volume control apparatus, an input audio signal is converted into an electric signal, the electric signal is compared with a threshold, an alarm signal is generated every time the electric signal exceeds the threshold, and then the adjusted audio signal is output.
According to research on noise-induced hearing loss, it is known that hearing loss is proportional to the total energy of noise, i.e., (audio volume×time). In other words, according to noise exposure standards, hearing loss is induced by exposure to 85 dB noise for 8 hours, 88 dB noise for 4 hours, 91 dB noise for 2 hours, and 97 dB noise for 30 minutes.
According to the conventional technique related to the volume control apparatus, a threshold for preventing hearing loss is set by referring to only audio volume.
As a result, even if the audio signal is adjusted to below the threshold, hearing loss may also be induced by long-time exposure to the audio signal.
Moreover, the conventional volume control apparatus does not consider a fact that the sensitivity of ears varies with audio frequency components. Since the human ears are generally insensitive to low-frequency sound, they may feel intermediate/high-frequency sound louder when they concentrate on low-frequency sound.
SUMMARY OF THE INVENTIONThe present general inventive concept provides an audio reproduction apparatus and method, in which an audio volume is automatically controlled based on audio energy and human auditory characteristics.
The present general inventive concept also provides an audio volume control apparatus and method to automatically control an audio volume based on human auditory characteristics.
Additional aspects and utilities of the present general inventive concept will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the general inventive concept.
The foregoing and/or other aspects and utilities of the present general inventive concept may be achieved by providing an audio reproduction method including splitting a reproduction audio signal into audio signals corresponding to a plurality of frequency bands, extracting audio energy for each of the frequency bands, and comparing the audio energy for each of the frequency bands with a predetermined threshold and controlling a volume of an output audio signal corresponding to each of the frequency bands.
The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing an audio reproduction apparatus including a band splitting unit to split a reproduction audio signal into audio signals corresponding to a plurality of frequency bands, an audio monitoring unit to accumulate reproduced audio energy for each of the frequency bands, to compare the accumulated audio energy for each of the frequency bands with a predetermined threshold, and to generate volume control information, and a volume control unit to control a volume of an input audio signal corresponding to each of the frequency bands according to the volume control information generated by the audio monitoring unit.
The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing an audio volume control method including presetting a volume step and a volume control value for each frequency band based on human auditory characteristics, splitting an audio signal into audio signals corresponding to a plurality of frequency bands, determining the volume control value preset for each frequency band according to an input volume value, controlling the volume of each of the split audio signals according to the volume control value determined for each of the frequency bands, and synthesizing the split audio signals corresponding to the frequency bands.
The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing an audio volume control apparatus including a storage unit to store a volume control value for each frequency band corresponding to a volume step based on human auditory characteristics, a band splitting unit to split an input audio signal into audio signals corresponding to a plurality of frequency bands, a volume processing unit to determine a volume control value for each frequency band, stored in the storage unit, according to an input volume value, a sub volume control unit to control a volume of each of the split audio signals according to the volume control value determined for each of the frequency bands by the volume processing unit, and a band synthesis unit to synthesize the split audio signals corresponding to the frequency bands whose volumes are controlled by the sub volume control unit.
The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing an audio volume control apparatus to reproduce a reproduction audio signal from an input audio signal, the audio volume control apparatus including a volume control unit to control a plurality of frequency bands of the input audio signal according to corresponding ones of characteristics of the respective frequency bands of the reproduction audio signal.
The characteristics of the respective frequency bands may include at least one of an audio reproduction time counted according to each sample value of the frequency bands and a threshold, and audio volume value generated according to each volume value of the frequency bands and a user input volume value.
The volume control unit may reproduce the reproduction audio signal from a previous input audio signal.
The volume control unit may control a volume of each of the plurality of frequency bands of the input audio signal according to a user input volume control signal and a corresponding one of characteristics of the respective frequency bands of the reproduction audio signal.
The user input volume control signal may include a signal to control an overall volume of the reproduction audio signal.
The user input volume control signal may include a signal to control a volume of each of the plurality of frequency bands of the reproduction audio signal.
The user input volume control signal may be compared to each of the corresponding one of characteristics of the respective frequency bands of the reproduction audio signal to generate a volume control signal to control each volume of the frequency bands of the input audio signal.
The characteristics of the respective frequency bands of the reproduction audio signal may include a reproduction time of each of frequency bands of the reproduction audio signal with respect to a reference.
The reproduction time may include the number of times counted when a level of each of the frequency bands of the reproduction audio signal is greater than a reference, for a predetermined period of time.
The characteristics of the respective frequency bands of the reproduction audio signal may include an audio energy of each of the frequency bands of the reproduction audio signal with respect to a reference.
The characteristics of the respective frequency bands of the reproduction audio signal may include a reproduction time and an audio energy of each of the frequency bands of the reproduction audio signal with respect to a reference
The audio volume control apparatus may further include a band splitting unit to split the production audio signal into the plurality of frequency bands and to split the input audio signal into the plurality of frequency bands.
The volume control unit may include sub-volume control units to correspond to the respective frequency bands.
Each of the sub-volume control units may measure a gain value of each of the frequency bands of the input audio signal, and compares the gain value of each of the frequency bands of the input audio signal with a corresponding volume control value to calculate a final gain value to be applied to the input audio signal
Each of the sub-volume control units may comprise a level measurement unit to measure a gain value of each of the frequency bands of the input audio signal, a level comparison unit to compare the gain value of each of the frequency bands of the input audio signal with a corresponding volume control value to generate a comparison result, and a level calculation unit to calculate a final gain value according to the comparison result, so that the final gain value is applied to the input audio signal.
The volume control unit may control a plurality of frequency bands of the input audio signal according to an equal loudness curve and the characteristics of the respective frequency bands of the reproduction audio signal.
The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing an audio volume control apparatus, including a volume control unit to reproduce a reproduction audio signal from an input audio signal and to control a plurality of frequency bands of a second input audio signal according to a reference volume signal and corresponding ones of characteristics of the respective frequency bands of the reproduction audio signal.
The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing a computer-readable medium containing computer-readable codes as a program to execute a method of an audio volume control apparatus, the method including reproducing a reproduction audio signal from an input audio signal, and controlling a plurality of frequency bands of a second input audio signal according to a reference volume signal and corresponding ones of characteristics of the respective frequency bands of the reproduction audio signal.
These and/or other aspects and utilities of the present general inventive concept will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
Reference will now be made in detail to the embodiments of the present general inventive concept, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present general inventive concept by referring to the figures.
Referring to
The frequency band splitting unit 110 splits a reproduction (or output) audio signal into audio signals corresponding to a plurality of frequency bands using a Frequency band pass filter or a quadrature mirror filter (QMF).
The audio monitoring unit 120 calculates the energy of an audio signal corresponding to each of the frequency bands based on a user input volume value and audio reproduction information corresponding to a predetermined period of time, compares the calculated energy with a predetermined threshold, and generates volume control information for a corresponding frequency band if the energy for the frequency band exceeds the threshold. At this time, the volume control information includes a volume control value and an alarm signal of a predetermined pattern.
The volume control unit 130 divides an input audio signal into audio signals corresponding to a plurality of frequency bands using a Frequency bandpass filter or a QMF and controls amplitude of the audio signal corresponding to each of the frequency bands differently according to a volume control value generated by the audio monitoring unit 120.
Referring to
The volume counting unit 220 calculates the average of reproduced audio samples for each of the frequency bands at predetermined time intervals and extracts the calculated average as an audio volume value for the frequency band.
In another exemplary embodiment of the present invention, the volume counting unit 220 compares a user input volume value with a reproduced audio volume value for each of the frequency bands and extracts an audio volume value (or loudness) for the frequency band.
The audio energy calculation unit 230 calculates audio energy for each of the frequency bands based on the counted audio reproduction time stored in the reproduction time counting unit 210 and/or the extracted audio volume value extracted by the volume counting unit 220. For example, audio energy E can be expressed by an integral equation as follows:
E=∫(T×V)dt (1)
where T indicates an audio reproduction time and V indicates an audio volume value.
The auditory threshold storage unit 240 stores a threshold value for each of the frequency bands in order to prevent hearing damage based on human auditory characteristics. Generally, the human auditory characteristics can be expressed as an equal loudness curve as illustrated in
The volume control processing unit 250 compares the threshold for each of the frequency bands, which is stored in the auditory threshold storage unit 240, with the audio energy for each of the frequency bands, which is calculated by the audio energy calculation unit 230, and generates volume control information, for example, an alarm signal of a particular pattern and a volume control signal indicating an excessive amount of the audio energy if the audio energy exceeds the threshold.
The alarm signal generation unit 260 generates an audio signal of the particular pattern every time it receives the alarm signal of the particular pattern from the volume control processing unit 250.
A frequency band splitting unit 310 splits the input audio signal into audio signals corresponding to a plurality of frequency bands using the frequency band pass filter and the QMF. A sub volume control unit 320 controls the volume of the audio signal split by the frequency band splitting unit 310 according to the volume control signal generated by the audio monitoring unit 120. For example, when the frequency band splitting unit 310 generates an audio signal corresponding to a first sub-frequency band, an audio signal corresponding to a second sub-frequency band, . . . , and an audio signal corresponding to an nth sub-frequency band, and the audio monitoring unit 120 generates a first volume control signal for the first sub-frequency band, a second volume control signal for the second sub-frequency band, . . . , and an nth volume control signal for the nth sub-frequency band. A first sub volume control unit 322 then increases or reduces an audio volume value for the first sub-frequency band according to the first volume control signal and the user input volume value, a second sub volume control unit 324 increases or reduces an audio volume value for the second sub-frequency band according to the second volume control signal and the user input volume value, and an nth sub volume control unit 326 increases or reduces an audio volume value for the nth sub-frequency band according to the nth volume control signal and the user input volume value. Thus, it is possible that when a user increases an audio volume, the volume of a low-frequency sound is maintained as is and the volume of an intermediate/high-frequency sound is increased. In addition, the volume of a frequency band in which much energy is accumulated is gradually reduced.
Adders 370 and 380 synthesize the audio signals for the frequency bands whose volumes are controlled by the sub volume control unit 320, thereby reconstructing the original audio signal.
Referring to
The frequency band splitting unit 410 splits an input audio signal into audio signals corresponding to one or more frequency bands using a frequency band pass filter or a QMF.
The equal loudness curve data storage unit 430 stores an audio volume control value for each frequency band according to a volume step by referring to an equal loudness curve. The audio volume control value is information about an audio volume value that has to be maintained for each frequency band.
The volume processing unit 420 reads the audio volume control value corresponding to a user input volume step from the equal loudness curve data storage unit 430.
The sub volume control unit 440 performs a dynamic range control on a volume of the audio signal corresponding to each frequency band split by the frequency band splitting unit 410 according to the audio volume control value for each frequency band that is read by the volume processing unit 420. In other words, the first sub dynamic range control unit 442 controls the volume of an audio signal corresponding to a first sub frequency band according to a volume control value for the first sub frequency band read by the volume processing unit 420. The second sub dynamic range control unit 444 controls the volume of an audio signal corresponding to a second sub frequency band according to a volume control value for the second sub frequency band read by the volume processing unit 420. The nth sub dynamic range control unit 446 controls the volume of an audio signal corresponding to an nth sub frequency band according to a volume control value for the nth sub frequency band read by the volume processing unit 420.
The frequency band synthesis unit 450 synthesizes the audio signals corresponding to the frequency bands whose volumes are controlled by the sub volume control unit 440 using an inverse QMF synthesis technique.
Referring to
Referring to
Physically measured sound pressure (or sound intensity) is not equal to volume that is actually perceived by the human auditory system. The human ears have irregular response property with respect to audible frequency sound. For example, the sensitivity of the human ears to sound of 1-5 kHz is very high, whereas the sensitivity of human ears to sound below or over 1-5 kHz is very low.
A graph showing the human auditory characteristics is called an equal loudness curve.
Referring to
Referring to
A level comparison unit 920 compares the volume control value for each frequency band read by the volume processing unit 420 with the gain value for the frequency band measured by the level measurement unit 910, so that a gain value g(n) is output according to the comparison result. For example, a gain value of an input audio signal X(n) is compared with a volume control value. When the gain value is less than the volume control value, the gain value is increased by the volume control value. When the gain value is greater than the volume control value, the gain value is reduced by the volume control value.
A gain calculation unit 930 calculates the gain value g(n) to be applied to the input audio signal X(n) using the gain value determined by the level comparison unit 920 and a previous gain value.
A delay unit 940 delays the input audio signal X(n) until the gain value g(n) to be applied to the input audio signal X(n) is calculated.
A multiplier 950 multiplies the input audio signal X(n) by the gain value g(n) calculated by the gain calculation unit 930, thereby generating an output audio signal Y(n).
Referring to
As described above, according to the present general inventive concept, a signal having components as shown in the equal loudness curve is the loudest sound that can be perceived by the human ears. Thus, an audio volume can be adjusted for each frequency band based on a user input volume value and the equal loudness curve. Moreover, an alarm signal can be generated for each frequency band when audio energy approximates a threshold. At the same time, unnecessary audio energy reproduction is prevented, thereby preventing hearing damage. Therefore, by automatically controlling the audio volume using audio energy accumulated for each frequency band, safe and reliable hearing protection can be achieved. Furthermore, by controlling the audio volume for each frequency band according to the equal loudness curve, an optimized equalizer can be implemented.
The present invention can also be embodied as computer readable code on a computer readable medium. The computer-readable medium may include a computer-readable recording medium and a computer-readable transmission medium. The computer readable recording medium is any data storage device that can store data which can be thereafter read by a computer system. Examples of the computer readable recording medium include read-only memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, and carrier waves. The computer readable transmission medium can also be distributed over network coupled computer systems, for example, a wired or wireless network or the Internet, so that the computer readable code is stored and executed in a distributed fashion.
Although a few embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the appended claims and their equivalents.
Claims
1. An audio reproduction method comprising:
- splitting a reproduction audio signal into audio signals corresponding to a plurality of frequency bands;
- extracting audio energy for each of the frequency bands; and
- comparing the audio energy for each of the frequency bands with a predetermined threshold to control a volume of an input audio signal corresponding to each of the frequency bands.
2. The audio reproduction method of claim 1, wherein the threshold comprises preset auditory characteristic data.
3. The audio reproduction method of claim 1, wherein the extraction of the audio energy comprises:
- counting a reproduction time of each audio signal having a higher level than a second predetermined threshold for a predetermined period of time and storing the counted reproduction time;
- extracting an audio volume value for each of the frequency bands; and
- calculating the audio energy based on the stored reproduction time and the extracted audio volume value.
4. The audio reproduction method of claim 1, wherein the controlling of the volume of the audio signal comprises:
- comparing the audio energy for each of the frequency bands with the predetermined threshold;
- generating a volume control signal every time the audio energy exceeds the predetermined threshold; and
- controlling the volume of the audio signal corresponding to each of the frequency bands according to the volume control signal.
5. The audio reproduction method of claim 1, further comprising:
- generating a predetermined alarm signal for a corresponding frequency band if the audio energy for the frequency band exceeds the predetermined threshold.
6. An audio reproduction apparatus comprising:
- a band splitting unit to split a reproduction audio signal into audio signals corresponding to a plurality of frequency bands;
- an audio monitoring unit to accumulate reproduced audio energy for each of the frequency bands, comparing the audio energy for each of the frequency bands with a predetermined threshold, and to generate volume control information; and
- a volume control unit to control a volume of an input audio signal corresponding to each of the frequency bands according to the volume control information generated by the audio monitoring unit.
7. The audio reproduction apparatus of claim 6, wherein the audio monitoring unit comprises:
- a reproduction time counting unit to count the reproduction time of an audio signal having a higher level than a predetermined threshold for a predetermined period of time;
- a volume counting unit to extract an audio volume value for each of the frequency bands;
- an audio energy calculation unit to calculate the audio energy for each of the frequency bands based on the stored reproduction time and the extracted audio volume value;
- a threshold storage unit to store auditory thresholds for the frequency bands based on human auditory characteristics; and
- a volume control processing unit to compare the audio energy for each of the frequency bands, calculated by the audio energy calculation unit, with the threshold for each of the frequency bands, stored in the threshold storage unit, and generating an alarm signal of a particular pattern and generating a volume control signal indicating an excessive amount of the audio energy from the threshold if the audio energy exceeds the threshold.
8. The audio reproduction apparatus of claim 7, wherein the volume control unit comprises:
- a second band splitting unit to split the input audio signal into second audio signals corresponding to the plurality of frequency bands; and
- a sub volume control unit to control the volume of each of the second audio signals split by the band splitting unit according to the volume control signal for each of the frequency bands.
9. An audio volume control method comprising:
- presetting a volume step and a volume control value for each frequency band based on human auditory characteristics;
- splitting an audio signal into audio signals corresponding to a plurality of frequency bands;
- determining the volume control value preset for each frequency band according to an input volume value;
- controlling the audio volume for each of the frequency bands split according to the volume control value determined for each of the frequency bands; and
- synthesizing the split audio signals corresponding to the frequency bands.
10. The audio volume control method of claim 9, wherein the controlling of the audio volume for each of the frequency bands split according to the volume control value comprises comparing the volume control value determined for each frequency band with a gain value of an audio signal corresponding to the frequency band, outputting a gain value corresponding to the comparison result, and applying a gain value obtained based on the output gain value and a previous gain value to an input audio signal, to generate an output audio signal.
11. An audio volume control apparatus comprising:
- a storage unit to store a volume control value for each frequency band corresponding to a volume step based on human auditory characteristics;
- a band splitting unit to split an audio signal into audio signals corresponding to a plurality of frequency bands;
- a volume processing unit to determine the volume control value for each frequency band, stored in the storage unit, according to an input volume value;
- a sub volume control unit to control the volume of each of the split audio signals according to the volume control value determined for each of the frequency bands by the volume processing unit; and
- a band synthesis unit to synthesize the split audio signals corresponding to the frequency bands whose volumes are controlled by the sub volume control unit.
12. The audio volume control apparatus of claim 11, wherein the band splitter may include band pass filters or quadrature mirror filters (QMFs).
13. The audio volume control apparatus of claim 11, wherein the volume control unit comprises:
- a level measurement unit to measure a gain value of the audio signals corresponding to each of the frequency bands;
- a level comparison unit to compare the volume control value determined for a frequency band with a gain value of an audio signal corresponding to the frequency band and outputting a gain value corresponding to the comparison result;
- a gain calculation unit to calculate a gain value to be applied to an input audio signal corresponding to the frequency band based on the output gain value and a previous gain value;
- a multiplier to multiply the input audio signal corresponding to the frequency band by the gain value calculated by the gain calculation unit, to generate an output audio signal.
14. An audio volume control apparatus to reproduce a reproduction audio signal from an input audio signal, comprising:
- a volume control unit to control a plurality of frequency bands of the input audio signal according to corresponding ones of characteristics of the respective frequency bands of the reproduction audio signal.
15. The audio volume control apparatus of claim 14, wherein the characteristics of the respective frequency bands comprise at least one of an audio reproduction time counted according to each sample value of the frequency bands and a threshold, and audio volume value generated according to each volume value of the frequency bands and a user input volume value.
16. The audio volume control apparatus of claim 14, wherein the volume control unit reproduces the reproduction audio signal from a previous input audio signal.
17. The audio volume control apparatus of claim 14, wherein the volume control unit controls a volume of each of the plurality of frequency bands of the input audio signal according to a user input volume control signal and a corresponding one of characteristics of the respective frequency bands of the reproduction audio signal.
18. The audio volume control apparatus of claim 17, wherein the user input volume control signal comprises a signal to control an overall volume of the reproduction audio signal.
19. The audio volume control apparatus of claim 17, wherein the user input volume control signal comprises a signal to control a volume of each of the plurality of frequency bands of the reproduction audio signal.
20. The audio volume control apparatus of claim 17, wherein the user input volume control signal is compared to each of the corresponding one of characteristics of the respective frequency bands of the reproduction audio signal to generate a volume control signal to control each volume of the frequency bands of the input audio signal.
21. The audio volume control apparatus of claim 14, wherein the characteristics of the respective frequency bands of the reproduction audio signal comprise a reproduction time of each of frequency bands of the reproduction audio signal with respect to a reference.
22. The audio volume control apparatus of claim 21, wherein the reproduction time comprises the number of times counted when a level of each of the frequency bands of the reproduction audio signal is greater than a reference, for a predetermined period of time.
23. The audio volume control apparatus of claim 14, wherein the characteristics of the respective frequency bands of the reproduction audio signal comprise an audio energy of each of the frequency bands of the reproduction audio signal with respect to a reference.
24. The audio volume control apparatus of claim 14, wherein the characteristics of the respective frequency bands of the reproduction audio signal comprise a reproduction time and an audio energy of each of the frequency bands of the reproduction audio signal with respect to a reference
25. The audio volume control apparatus of claim 14, further comprising:
- a band splitting unit to split the production audio signal into the plurality of frequency bands and to split the input audio signal into the plurality of frequency bands.
26. The audio volume control apparatus of claim 14, wherein the volume control unit comprises sub-volume control units to correspond to the respective frequency bands.
27. The audio volume control apparatus of claim 26, wherein each of the sub-volume control units measures a gain value of each of the frequency bands of the input audio signal, and compares the gain value of each of the frequency bands of the input audio signal with a corresponding volume control value to calculate a final gain value to be applied to the input audio signal
28. The audio volume control apparatus of claim 26, wherein each of the sub-volume control units comprises:
- a level measurement unit to measure a gain value of each of the frequency bands of the input audio signal;
- a level comparison unit to compare the gain value of each of the frequency bands of the input audio signal with a corresponding volume control value to generate a comparison result; and
- a level calculation unit to calculate a final gain value according to the comparison result, so that the final gain value is applied to the input audio signal.
29. The audio volume control apparatus of claim 26, wherein the volume control unit controls a plurality of frequency bands of the input audio signal according to an equal loudness curve and the characteristics of the respective frequency bands of the reproduction audio signal.
Type: Application
Filed: Aug 28, 2007
Publication Date: Aug 7, 2008
Applicant: Samsung Electronics Co., Ltd. (Suwon-si)
Inventor: Chi-ho Jung (Seoul)
Application Number: 11/845,815
International Classification: A61F 11/06 (20060101);