Audio reproduction method and apparatus with auto volume control function

Abstract

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.

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.