Method and apparatus for automatically compensating sound volume

An apparatus for automatically compensating a sound volume in a sound playback device which plays back sound with a provision of an external audio signal or an aerial audio signal, comprising:

• a low-pass filter and amplifier for removing high frequency noise elements included in an input audio signal and amplifying the resultant signal to a predetermined level, wherein the frequency characteristic of the low-pass filter is an inverse function of a loudness curve;
• an energy detecting unit for calculating an energy of the audio signal amplified in the low-pass filter and amplifier;
• a microcomputer for adding up an energy value of the audio signal obtained by the energy detecting unit for a predetermined time period, comparing the audio signal energy value with one obtained at a previous step thereof, and outputting a volume-compensated control signal corresponding to the compared resultant value;
• and
• a volume control unit for compensating an amplification rate of the input audio signal in accordance with the volume-compensated control signal;
• wherein the energy detecting unit comprises
• a trigger unit for converting the input audio signal to a square wave signal;
• a multiplier for multiplying a clock signal to the spherical wave signal and generating a clock-loaded modulation wave signal only for the voiced internal;
• an asynchronous counter for counting an output signal of the multiplier;
• a D/A (digital/analog) converter for converting an output value of the asynchronous counter to an analog signal;
• and
• a signal interpreter for analyzing the input audio signal applied for a predetermined time period on ground of an energy value of an audio signal outputted from the D/A converter, and resetting the asynchronous counter at respective intervals thereof.

A method for automatically compensating a sound volume, comprising:

• an input determination step for confirming whether an input mode of an audio signal is modified or a channel is modified;
• a signal processing step for low-pass filtering and amplifying the input audio signal, wherein a frequency characteristic of the low-pass filtering is an inverse function of a loudness curve;
• an energy production step for calculating an energy value of the input audio signal by predetermined cycles, and obtaining an average energy value of the calculated energy value and an energy value obtained at a previous step thereof;
• an audio mode determination step for separating the input audio signaling to voiced intervals and voiceless intervals, counting the voiced intervals and the voiceless intervals in accumulation, and determining whether the input audio signal is in a music mode or in a voice mode on the ground of the accumulated counted voice intervals and voiceless intervals;
• and
• a mode volume compensation step for calculating a compensated amount of the audio signal in consideration of an energy value produced in the energy production step and the audio mode, and carrying out a volume compensation in accordance with the calculated value.

An apparatus for automatically compensating a sound volume in an audio device which amplifies and outputs a sound volume of an input audio signal in accordance with a user's requirement, comprising:

• a switching unit for transferring an input audio signal to an A/D converter when the input audio signal mode is converted or a broadcasting channel is switched;
• an energy detecting unit for receiving a digital audio signal outputted from the A/D converter, and obtaining and accumulating therein an energy value of respective intervals by predetermined cycles;
• an audio mode determining unit for comparing energy values of the obtained respective intervals with a reference energy value, counting in accumulation the intervals determined as voiced and unvoiced in accordance with the compared resultant value, and determining an input audio signal mode on the ground of the accumulated count value;
• a compensated amount calculating unit for obtaining an entire energy of the input audio signal on the ground of the number of the voiced intervals counted during the predetermined frame period, obtaining a difference of the obtained entire energy and the reference energy value, and calculating a volume-compensated value in accordance with the difference value and the determined audio mode;
• and
• a digital signal processing unit including a multiplier for multiplying a volume of the audio signal outputted from the A/D converter by use of the volume-compensated value.