KR101067595B1 - Apparatus for compensating low frequency band audio signal based on listenr's characteristics - Google Patents

Abstract

The present invention relates to a multimedia service, and more particularly, to improve a reproduction quality of an audio signal.

According to the present invention, a frequency band dividing unit for dividing a frequency band of an audio signal into a plurality of sub frequency bands, includes a minimum perceived volume information of an audio signal of each sub frequency band of a listener, and an audible frequency range information of the listener. And a low band compensator for controlling the volume of the audio signal within the audible frequency range above the minimum perceived volume information based on the auditory characteristic information storage unit storing the auditory characteristic information. An audio compensation device is provided.

Low frequency, hearing characteristics, loudness

Description

An audio signal reproducing device that compensates for low-band audio signals based on the listener's listening characteristics {APPARATUS FOR COMPENSATING LOW FREQUENCY BAND AUDIO SIGNAL BASED ON LISTENR'S CHARACTERISTICS}

The present invention relates to a multimedia service, and more particularly, to improve a reproduction quality of an audio signal. The present invention is derived from a study performed as part of the IT source technology development project of the Ministry of Knowledge Economy [Task management number: 2008-F-011-01, Task name: Next-generation DTV core technology development project]

The present invention provides more high-quality audio to each individual when listening to multimedia with headphones or earphones generally used when playing multimedia on a portable multimedia playback device such as an MP3 player, a PMP, a DMB playback device, a mobile phone, or a PC. It is a technology that can be done.

Recently, many people use multimedia devices such as MP3 Player, PMP, mobile phone, DMB Player, etc. to watch multimedia, and listeners listen to audio through small speakers belonging to the terminal or headphones / earphones. Doing. The small speakers included in such portable terminals and headphones / earphones do not have the ability to properly reproduce low frequency sounds, and as a result, the sound output from the system using the small speakers does not output high quality audio.

In order to solve this problem, existing low frequency enhancement systems have used a method of compensating for low frequency sound by emphasizing or amplifying arbitrary low frequency signals before sending a signal to a speaker. Highly amplifying low frequency signals, however, must deliver tremendous amounts of energy to the loudspeakers and therefore drive the speakers with greater power. However, this method results in overdriving the speakers, which results in increased background noise, distortion, and damage to the speakers.

Therefore, when sound is reproduced by a small speaker used in a mobile terminal and a headphone / earphone, there is a limit to sufficiently reproduce low sound, and thus a low frequency reproduction band extension technology has been developed to solve this problem. This technique is based on the 'Missing Fundamental' theory, in order to produce psychoacoustically low frequencies, a band above the cutoff frequency with respect to the fundamental frequency of the low band component that is below the cutoff frequency of the small speaker. Is a technique to add a compensating audio signal to a. Thus, the listener can feel low frequency components (present in the band below the cutoff frequency) that cannot be reproduced in the small speaker by the added compensation audio signal.

Typical commercialization products for low frequency reproduction band extension technologies include US Waves MaxxBass and SRS SRS TruBass. However, since the low band perception ability of each listener is different and the performances of the portable terminal and the reproduction band of the headphone / earphone are different, the situation is that they do not provide effective performance.

It is an object of the present invention to reproduce high quality audio signals based on the personal listening characteristics of the listeners listening to the audio signals.

In order to achieve the above object and solve the problems of the prior art, the present invention provides a frequency band dividing unit for dividing a frequency band of an audio signal into a plurality of sub-frequency bands, the minimum recognition of the audio signal of each sub-frequency band of the listener. Based on the auditory characteristic information storage unit for storing auditory characteristic information including volume information and audible frequency range information of the listener and the auditory characteristic information, the volume of the audio signal within the audible frequency range is controlled above the minimum perceived volume information. It provides a low-band audio compensation device comprising a low band compensation unit.

According to an aspect of the present invention, an audible frequency range determination unit for determining an audible frequency range of a listener for an input audio signal, including in the audible frequency band of the hearing loss audio signal of a frequency band lower than the audible frequency band of the input audio signal A low-band audio, comprising: a compensation audio signal generator for generating a compensated audio signal; an audio combiner for combining the input audio signal and the compensated audio signal; and an audio signal reproducing unit for reproducing the combined audio signal A signal compensation device is provided.

According to the present invention, high quality audio can be reproduced in consideration of the personal listening characteristics of the audio signal listener.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing the structure of a low-band audio compensation apparatus according to an embodiment of the present invention. Hereinafter, an operation of a low band audio compensation device according to the present invention will be described in detail with reference to FIG. 1. The low-band audio compensation device 100 according to the present invention includes a frequency band divider 110, a reference audio signal generator 120, an auditory characteristic information update unit 130, an auditory characteristic information storage unit 140, and a low band. Compensation unit 150 is included.

The frequency band dividing unit 110 divides a frequency band of an input audio signal input to the low band audio compensation device 110 into a plurality of sub frequency bands.

The auditory characteristic information storage unit 130 stores auditory characteristic information including minimum perceived volume information of the audio signal of each sub-frequency band of the listener who listens to the input audio signal and audible frequency range information of the listener.

Since a small audio device is usually equipped with a small speaker, audio signals below a certain frequency cannot be reproduced. In addition, the frequency range of the audio signal that can be heard for each listener is different. Therefore, the auditory characteristic information storage unit 130 stores a different audio frequency range according to each listener. Hereinafter, a frequency range of an audio signal that a specific listener can hear is called an audible frequency band, and a frequency range of an audio signal that a listener cannot hear is called a hearing loss frequency band.

If the audio signal is in a frequency band that both listeners can hear, the two listeners do not recognize the audio signal with the same magnitude. The first listener can recognize the barely audible audio signal and the second listener can perceive the loud audio signal. Therefore, the auditory characteristic information storage unit 130 stores different minimum perceived volume information according to each listener.

Hereinafter, the listening characteristics of the listener will be described in detail with reference to FIG. 2.

The reference audio signal generator 120 generates a plurality of reference audio signals at predetermined frequency intervals in each sub frequency band.

The reference audio signal generator 120 may generate a plurality of reference audio signals at predetermined frequency intervals in a sub frequency band of at least the lowest audible frequency. According to an embodiment of the present invention, each audio signal may be a sinusoidal file corresponding to the center frequency of each sub frequency band.

The auditory characteristic information updating unit 130 may update the audible frequency range information according to whether the listener has listened to the reference audio signal. The patent auditory characteristic information updating unit 130 may store the lowest frequency of the audio signal that the listener can hear as the lowest audible frequency.

According to an embodiment of the present invention, the reference audio signal generator 120 may generate a reference audio signal having a predetermined volume for a sub frequency band of at least the lowest audible frequency.

Also, the auditory characteristic information updating unit 130 may update the minimum perceived volume information for each sub frequency band according to whether the listener has listened to the reference audio signal for each sub frequency band.

The low band compensator 150 controls the volume of the audio signal in the audio frequency range above the listener's minimum perceived volume based on the auditory characteristic information of each listener. According to an embodiment of the present invention, the low band compensation unit 150 is an integer multiple of the frequency of the hearing loss audio signal with respect to the hearing loss audio signal of a lower frequency band than the audio frequency band, and compensates for the audio signal included in the audio frequency band Can be generated. The low band compensation unit 150 may increase the volume of a specific frequency by combining the compensation audio signal with the input audio signal.

According to an embodiment of the present invention, the low band compensation unit 150 may control the volume of the compensation audio signal in consideration of the loudness level according to the frequency of the compensation audio signal. The loudness level represents the degree of volume recognition of the listener according to the frequency. That is, if the loudness levels are the same, the listener recognizes audio signals of different volumes at different frequencies as the same volume.

The low band compensator 150 may determine a difference of the listener's minimum perceived volume information and the loudness level value for a specific frequency band as the volume of the compensated audio signal. The listener can recognize the audio signal by adding a compensating audio signal to the volume of the audio signal that the listener could not recognize.

In the present invention, the volume of the compensated audio signal is determined in consideration of the listening characteristics of each listener. Therefore, the audio signal of sound quality optimized for each listener can be reproduced.

2 is a diagram illustrating a concept of controlling a volume of a compensation audio signal in consideration of a loudness level according to an embodiment of the present invention. Hereinafter, the concept of controlling the volume of the compensated audio signal according to the present invention will be described in detail with reference to FIG. 2.

Human ears respond to sounds of the same sound pressure level differently depending on their frequency. In other words, the human ear responds most sensitively around 2-3 kHz and less sensitively in the areas of high and low frequencies. Considering these effects, the loudness curve is obtained by measuring the sound pressure level for each frequency heard with the same loudness. The unit representing the loudness of this sound is called Phon. A pawn refers to a sound pressure level of 1 kHz pure sound, which is felt to have the same loudness as an ear. For example, a 100-phone sound means a sound pressure level corresponding to that of a 1 kHz pure sound having a sound pressure level of 100 dB.

Referring to the loudness diagram shown in FIG. 2, the sound pressure level is lowest in the vicinity of 4 KHz, and the sound pressure level increases as the frequency increases. This means that the listener is very sensitive to audio signals around 4KHz, so even small sounds can be perceived as '0 phone', but they are rather insensitive to low frequency bands, such as 100Hz, and perceive a relatively loud sound as '0 phone'. to be.

The loudness level can be different for each listener. That is, the second listener may not be able to listen to the audio signal that can be heard by the first listener.

In addition, the loudness level may vary depending on the reproduction capability of the audio signal reproducing apparatus. In other words, the expensive audio system provided in the living room can reproduce the audio signal of very low frequency according to the volume intended by the recorder. However, low-cost earphones connected to mobile phones, mp3 players, etc. may not play low-frequency audio signals or may play at a volume lower than the volume intended by the recorder.

Therefore, the listener may not be able to listen to an audio signal that can be heard using an expensive audio system using a mobile phone, an mp3 player, or the like.

The low-band audio compensation device according to the present invention can reproduce an optimal audio signal based on the individual characteristics of the listener and the characteristics of the audio signal reproducing apparatus.

3 is a block diagram illustrating a structure of a low band audio compensation apparatus according to another embodiment of the present invention. Hereinafter, an operation of the low band audio compensation apparatus according to the present invention will be described in detail with reference to FIG. 3. The low-band audio compensator 300 according to the present invention includes a frequency band divider 310, an audible frequency range determiner 320, a compensating audio signal generator 330, an audio combiner 340, and an audio signal reproducer. And 350.

The frequency band dividing unit 310 divides the frequency band of the input audio signal into a plurality of sub frequency bands.

The audible frequency range determiner 320 may determine an audible frequency range of the listener for the input audio.

According to an embodiment of the present invention, the compensation audio signal generator 330 may generate a compensation audio signal for each sub frequency band. The audio signal reproducing unit 350 reproduces the compensated audio signal for each sub frequency band, and the audible frequency range determiner 320 determines the audio frequency according to whether the listener reproduces the compensated audio signal for each sub frequency band. The range can be determined.

That is, when the listener does not hear the compensated audio signal for a particular sub frequency band, the audible frequency range determiner 320 may determine the sub frequency band including the compensated audio signal that the listener did not hear as the hearing loss frequency band. have.

The audio combiner 340 combines the input audio signal and the compensated audio signal. The volume of the input audio signal is increased as the compensation audio signal is added.

The audio signal reproducing unit 350 reproduces the audio signal in which the input audio signal and the compensation audio signal are combined.

The listener hears the compensating audio signal included in the audible frequency range and recognizes that the audio signal in the hearing loss frequency range is reproduced. Since the hearing loss audio signal that is not reproduced in the speaker or is reproduced at a very small volume is recognized as the volume amplified by the compensating audio signal, the listener recognizes that the audio signal is of good quality.

According to an embodiment of the present invention, the compensating audio signal generator 330 may generate a reference audio signal of a specific sub-frequency band in order to determine a listening characteristic of the listener. In this case, the reference audio signal may be a sine file whose frequency is the center frequency of the sub frequency band.

In addition, according to an embodiment of the present invention, the frequency of the reference audio signal may be an integer multiple of the frequency of the hearing loss audio signal.

According to an embodiment of the present invention, the audio signal reproducing unit 350 reproduces a reference audio signal of a specific sub-frequency band at a first volume, and the compensating audio signal reproducing unit 330 allows a listener to make a reference audio of the first volume. The volume of the reference audio signal may be controlled according to whether or not the signal is listened to. If the listener does not hear the reference audio signal reproduced at the first volume, the compensating audio signal reproducing unit 330 may determine that the listener's minimum perceived volume for the specific sub-frequency band is greater than or equal to the first volume.

According to an embodiment of the present invention, when the listener does not listen to the reference audio signal reproduced at the first volume, the audio signal reproducing unit 350 may reproduce the reference audio signal at a second volume greater than the first volume. have.

If the listener has listened to the reference audio signal reproduced at the second volume, the compensating audio signal generator 330 determines that the listener's minimum perceived volume for the particular sub frequency band is greater than the first volume and less than the second volume. can do.

According to an embodiment of the present invention, the compensating audio signal generator 330 may determine the minimum perceived volume of the listener for all sub-frequency bands included in the audible frequency range.

According to an embodiment of the present invention, the compensation audio signal generator 330 may control the volume of the compensation audio signal in consideration of the loudness level according to the frequency of the compensation audio signal. The loudness level indicates how loud the audio signal of a particular frequency is perceived by the listener. The compensation audio signal generator 330 may determine the volume of the compensation audio signal as much as the difference between the specific loudness level and the minimum perceived volume.

The listener may recognize the audio signal of the hearing loss frequency band as a compensation audio signal included in the audio frequency range is added to the audio signal of the hearing loss frequency band other than the audio frequency range. The listener can recognize the audio signal of the hearing loss frequency band at a specific loudness level.

The listener may recognize the audio signal reproduced by the audio signal reproducing unit 350 or less than the minimum perceived volume of the listener.

4 is a flowchart illustrating a method for updating auditory characteristic information according to an embodiment of the present invention step by step. Hereinafter, a method of updating auditory characteristic information according to the present invention will be described in detail with reference to FIG. 4.

In operation S430, the low band audio compensation device 410 reproduces the reference audio signal of the specific sub frequency band. According to an embodiment of the present invention, the reference audio signal may be a sinusoidal file having a center frequency of a specific sub-frequency band as a frequency.

In step S440, the listener listens to the reference audio signal and determines whether it can recognize it. If the frequency of the reference audio signal is not included in the listener's audible frequency range, the listener does not recognize the reference audio signal.

In step S450, the low band audio compensation device 410 determines the listener's audible frequency range according to the response from the listener. According to an embodiment of the present invention, the low-band audio compensation device 410 may reproduce the reference audio signal in step S430 and wait for a response from the listener for a predetermined time. If the listener does not respond for more than a predetermined time, the low band audio compensation device 410 may determine that the listener does not recognize the reference audio signal.

In operation S460, the low band audio compensation device 410 generates a reference audio signal for each sub frequency band.

In step S470, the listener determines whether the reference audio signal can be recognized.

If the listener does not recognize the reference audio signal, the low band audio compensation device 410 may increase the volume of the reference audio signal and play back the reference audio signal. According to an embodiment of the present invention, the low-band audio compensation device 410 may increase the volume of the reference audio signal until the listener recognizes it.

In operation S480, the low band audio compensation apparatus 410 may determine the volume of the reference audio signal when the listener recognizes the reference audio signal as the minimum perceived volume information of the listener for the specific sub frequency band. The low band audio compensation device 410 may update the minimum perceived volume information as the auditory characteristic information.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

1 is a block diagram showing the structure of a low-band audio compensation apparatus according to an embodiment of the present invention.

2 is a diagram illustrating a concept of controlling a volume of a compensation audio signal in consideration of a loudness level according to an embodiment of the present invention.

3 is a block diagram illustrating a structure of a low band audio compensation apparatus according to another embodiment of the present invention.

4 is a flowchart illustrating a method for updating auditory characteristic information according to an embodiment of the present invention step by step.

Claims (10)

A frequency band dividing unit dividing a frequency band of the audio signal into a plurality of sub frequency bands; An auditory characteristic information storage unit for storing auditory characteristic information including minimum perceived volume information of the audio signal of each sub frequency band of a listener and audible frequency range information of the listener; And The audible frequency range is generated by generating a compensation audio signal that is an integer multiple of the frequency of the hearing loss audio signal and included in the audible frequency band, for a hearing loss audio signal having a frequency band lower than the audible frequency band based on the auditory characteristic information. Low band compensation unit for controlling the volume of the audio signal within the above minimum recognition volume information Low band audio compensation device comprising a. The method of claim 1, A reference audio signal generator configured to generate a reference audio signal having a predetermined volume in each sub frequency band; And An auditory characteristic information updating unit for updating the minimum perceived volume information according to whether the listener has listened to the reference audio signal The low-band audio compensation device further comprises. The method of claim 1, A reference audio signal generator configured to generate a plurality of reference audio signals at predetermined frequency intervals in the sub frequency bands; And An auditory characteristic information updating unit for updating the audible frequency range information according to whether the listener can hear the reference audio signal The low-band audio compensation device further comprises. delete The method of claim 1, wherein the low band compensation unit, And controlling the volume of the compensated audio signal in consideration of a loudness level according to the frequency of the compensated audio signal. An audible frequency range determiner for determining an audible frequency range of the listener for the input audio signal; A compensation audio signal generator configured to generate a compensation audio signal included in the audible frequency band of the input audio signal in a hearing frequency band lower than the audible frequency band, and having a frequency that is an integer multiple of the frequency of the hearing loss audio signal; An audio combiner configured to combine the input audio signal and the compensated audio signal; And An audio signal reproducing unit reproducing the combined audio signal Low band audio signal compensation device comprising a. delete The method of claim 6, A frequency band dividing unit dividing a frequency band of the input audio signal into a plurality of sub frequency bands; More, The audio signal reproducing unit reproduces a reference audio signal of a specific sub frequency band at a first volume, And the compensated audio signal generator controls the volume of the compensated audio signal according to whether the listener has listened to the reference audio signal of the first volume. The method of claim 8, The audio signal reproducing unit reproduces the reference audio signal of the specific sub frequency band at a second volume greater than the first volume when the listener does not listen to the reference audio signal of the additional specific sub frequency band. And the compensated audio signal generator controls the volume of the compensated audio signal according to whether or not the reference audio signal of the second volume is listened to. The method of claim 6, wherein the compensation audio signal generation unit, And controlling the volume of the compensated audio signal in consideration of a loudness level according to the frequency of the compensated audio signal.

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