Abstract:
The present invention relates to a method for hearing protection in an ambient environment of a sound reproduction device, includes steps of: receiving analog audio signals from an audio signal source via a connector; converting the analog audio signals to digital audio signals; sampling the digital audio signals to obtain a plurality of sampled amplitude values; computing an actual audio energy of the digital audio signals within a predetermined time period setting the sampled amplitude values sampled within the predetermined time period as parameters; collecting ambient noises to compute a noise level; obtaining an audio reference energy according to the noise level; comparing the actual audio energy with the audio reference energy; generating a hearing protect signal if the actual audio energy reaches the audio reference energy; and changing a current gain value or emitting reminding information, thus, protecting listeners&#39; hearing. The present invention further provides a corresponding sound reproduction device.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a sound reproduction device and method for hearing protection in an ambient environment, especially to a sound reproduction device and method for evaluating noise level, and automatically adjusting a default gain value or emitting prompt information according to the noise level. 
         [0003]    2. Description of Related Art 
         [0004]    The continuous development of new digital technologies has made portable audio devices (such as MP3 player) popular. When environmental noise external of the portable audio device is loud or when a favorite song is played, a listener commonly increases a gain value of the portable audio device. However listeners all have a physiological hearing threshold, i.e., loudness discomfort level (LDL). If the listener is exposed to a noise level that is larger than the listener&#39;s LDL for a long time, the listener&#39;s hearing may be impaired. 
         [0005]    In order to solve the problems mentioned, there is a common gain control apparatus and method available in the market. The gain control apparatus provides a noise level-gain value index. The noise level-gain value index lists a plurality of gain values corresponding to noise level ranges. The gain control apparatus collects ambient noise, and computes a noise level of the ambient noise in a predetermined time field; obtaining a predetermined gain value corresponding to the noise level from the noise level-gain value index; adjusts a gain value to the predetermined gain value. Whereby the gain value of the gain control apparatus is changeable along with the noise level. 
         [0006]    However, if a listener is in an environment where the noise level changes frequently, the gain control apparatus will frequently change the gain value accordingly. As a result, the listener will be uncomfortable. Furthermore, audio signals with different amplitudes will have different loudness at a same gain value. 
         [0007]    Therefore, a heretofore unaddressed need exists in the industry to overcome the aforementioned deficiencies and inadequacies. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides a sound reproduction device and method for hearing protection while reproducing sounds in an ambient environment. The sound reproduction device and method evaluates noise level, and automatically changes a current gain value, or emitting prompt information according to the noise level. 
         [0009]    In a first aspect of the invention, the sound reproduction device includes a connector, an audio ADC, a gain amplifier, and an electro-acoustic transducer. The connector is configured for attaching to an audio signal source. The gain amplifier receives analog audio signals from the audio signal source via the connector, and amplifying the analog audio signals. The electro-acoustic transducer reproduces prompt sounds corresponding to the amplified analog audio signals. The audio ADC receives the analog audio signals from the audio signal source via the connector, and converts the analog audio signals to digital audio signals. The sound reproduction device further includes a storage unit, a processing unit, a microphone, and a noise ADC. The microphone collects ambient noises to generate analog noise signals. The noise ADC converts the analog noise signals to digital noise signals. The storage unit stores a default gain value. The processing unit includes an amplitude sampling module, a gain obtaining module, an energy computing module, and a noise processing module. The amplitude sampling module receives the digital audio signals from the audio ADC, samples the digital audio signals to obtain a plurality of sampled amplitude values. The gain obtaining module obtains the default gain value from the storage unit. The energy computing module computes an actual audio energy of the digital audio signals within a predetermined time period according to the default gain value and the sampled amplitude values sampled within the predetermined time period. The noise processing module computes a noise level according to the digital noise signals generated by the noise ADC, obtaining an audio reference energy according to the noise level, comparing the actual audio energy with the audio reference energy, and generating a hearing protect signal if the actual audio energy reaches the audio reference energy. 
         [0010]    In a second aspect of the invention, the sound reproduction device includes a connector, an audio ADC, and an electro-acoustic transducer. The connector is configured for attaching to an audio signal source. The electro-acoustic transducer receives analog audio signals from the audio signal source via the connector, and reproduces sounds corresponding to the amplified analog audio signals. The audio ADC receives the analog audio signals from the audio signal source via the connector, and converts the analog audio signals to digital audio signals. The sound reproduction device further includes a processing unit, a microphone, and a noise ADC. The microphone collects ambient noises to generate analog noise signals. The noise ADC converts the analog noise signals to digital noise signals. The processing unit includes an amplitude sampling module, an energy computing module and a noise processing module. The amplitude sampling module receives the digital audio signals from the audio ADC, samples the digital audio signals to obtain a plurality of sampled amplitude values. The energy computing module computes an actual audio energy of the digital audio signals within a predetermined time period according to the sampled amplitude values sampled within the predetermined time period. The noise processing module computes a noise level according to the digital noise signals generated by the noise ADC, obtaining an audio reference energy according to the noise level, comparing the actual audio energy with the audio reference energy, and generating a hearing protect signal if the actual audio energy reaches the audio reference energy. 
         [0011]    The hearing protection method includes the steps of: receiving analog audio signals from an audio signal source via a connector; converting the analog audio signals to digital audio signals; sampling the digital audio signals to obtain a plurality of sampled amplitude values of the digital audio signals; computing an actual audio energy of the digital audio signals within a predetermined time period setting the sampled amplitude values sampled within the predetermined time period as parameters; collecting ambient noises to compute a noise level; obtaining an audio reference energy according to the noise level; comparing the actual audio energy with the audio reference energy; and generating a hearing protect signal if the actual audio energy reaches the audio reference energy. 
         [0012]    Other systems, methods, features, and advantages will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a schematic diagram of a hardware infrastructure of a sound reproduction device for hearing protection in an ambient environment in accordance with a first preferred embodiment of the present invention; 
           [0014]      FIG. 2  is a block diagram of a hardware infrastructure of the sound reproduction device of  FIG. 1  in accordance with the first preferred embodiment of the present invention; 
           [0015]      FIG. 3  is a schematic diagram of main function modules of a processing unit of  FIG. 2 ; 
           [0016]      FIG. 4  is a flowchart of a preferred hearing protection method in the ambient environment by utilizing the sound reproduction device of  FIG. 2 ; 
           [0017]      FIG. 5  is a schematic diagram of a hardware infrastructure of a sound reproduction device for hearing protection in the ambient environment in accordance with a second preferred embodiment of the present invention; 
           [0018]      FIG. 6  is a block diagram of a hardware infrastructure of the sound reproduction device of  FIG. 5  in accordance with the second preferred embodiment of the present invention; 
           [0019]      FIG. 7  is a schematic diagram of main function modules of a processing unit of  FIG. 6 ; and 
           [0020]      FIG. 8  is a block diagram of a hardware infrastructure of the sound reproduction device in accordance with a third preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    In the following embodiments, for simplicity, a hearing protection function incorporated in a sound reproduction device, such as an earphone, is depicted. The sound reproduction device of the present invention allows hearing protection while reproducing sounds in an ambient environment. The following detailed description of the embodiments is made with reference to the attached drawings. 
         [0022]      FIG. 1  is a schematic diagram of a hardware infrastructure of the sound reproduction device for hearing protection in accordance with a first preferred embodiment of the present invention. The sound reproduction device  10  includes a connector  12 , a hearing protection unit  13 , and an electro-acoustic transducer  14 . The audio signal source  11  may be a music player, a radio player, a TV set, and so on. The sound reproduction device  10  receives analog audio signals from an audio signal source  11  via the connector  12 , and sends the analog audio signals to the hearing protection unit  13 . 
         [0023]    The hearing protection unit  13  is configured for converting the analog audio signals to digital audio signals, computes an audio energy of the digital audio signals within a predetermined time period, and when the audio energy reaches a predetermined value, automatically changes a default gain value to a reduced gain value. 
         [0024]    The electro-acoustic transducer  14  receives the analog audio signal sent from the audio signal source  11 , and reproduces sounds corresponding to the analog audio signals. The electro-acoustic transducer  14  may be an earphone or a speaker. 
         [0025]      FIG. 2  is a block diagram of a hardware infrastructure of the sound reproduction device of  FIG. 1  in accordance with the second preferred embodiment. The hearing protection unit  13  includes an audio analog-to-digital converter (ADC)  15 , a processing unit  16 , a storage unit  17 , and a gain amplifier  18 . The storage unit  17  stores a default gain value. The storage unit  17  may be a flash storage, a hard disk driver, and the like. 
         [0026]    The gain amplifier  18  is configured for receiving and amplifying the analog audio signals from the audio signal source  11  via the connector  12 , thereby yielding amplified analog audio signals that is sent to the electro-acoustic transducer  14 . The audio ADC  15  receives the analog audio signals from the audio signal source  11  via the connector  12 , converts the analog audio signals to digital audio signals, and sends the digital audio signals to the processing unit  16 . 
         [0027]    Referring to  FIG. 3 , the processing unit  16  includes an amplitude sampling module  160 , a gain obtaining module  161 , an energy computing module  162 , a noise processing module  163 , and a hearing protection module  164 . 
         [0028]    The amplitude sampling module  160  receives the digital audio signals from the audio ADC  15 , and samples the digital audio signals to obtain a plurality of sampled amplitude values of the digital audio signals. The gain obtaining module  161  obtains the default gain value from the storage unit  17 . 
         [0029]    The energy computing module  162  computes an actual audio energy of the digital audio signals within the predetermined time period by: Q=[Σ(mi*V) 2 /N] 1/2 , wherein Q represents the actual audio energy, V presents the default gain value, mi presents the sampled amplitude values sampled within the predetermined time period, N represents a count of the sampled amplitude values sampled within the predetermined time period, and i denotes an identifier of the sampled amplitude value. 
         [0030]    The hearing protection unit  13  further includes a microphone  19  and a noise ADC  20 . The microphone  19  is configured for collecting ambient noises, and for generating analog noise signals. The noise ADC  20  is configured for converting the analog noise signals to digital noise signals. 
         [0031]    The noise processing module  163  computes a noise level according to the digital noise signals, and computes an audio reference energy according to the noise level. In a first preferred method, the noise processing module  163  subtracts a predetermined noise level from the noise level to obtain a margin, divides the margin by the predetermined noise level to obtain the changed ratio, i.e., changed ratio=(noise level−predetermined noise level)/predetermined noise level, and multiplies the changed ratio with a predetermined audio energy to obtain the audio reference energy. 
         [0032]    In an alternative preferred method, the storage unit  17  further stores a noise level-audio energy index. The noise level-audio energy index is a table that lists the audio reference energys according to noise level ranges. The noise processing module  163  searches the noise level-audio energy index with the noise level to obtain the audio reference energy correspondingly. 
         [0033]    The noise processing module  163  compares the actual audio energy with the audio reference energy, and generates a hearing protect signal if the actual audio energy reaches the audio reference energy. The reference audio energy is an upper threshold value (loudest sound intensity) appropriate for a listener. 
         [0034]    When the hearing protection module  164  receives the hearing protect signal, the hearing protection module  164  automatically changes the default gain value to the reduced gain value, signals the gain amplifier  18  to amplify the analog audio signals received from the audio signal source  11  with the reduced gain value, and updates the default gain value in the storage unit  17  with the reduced gain value. 
         [0035]    In an alternative preferred embodiment, when the hearing protection module  164  receives the hearing protect signal the hearing protection module  164  sends prompt signals to the gain amplifier  18 . The gain amplifier  18  is configured for receiving and amplifying the prompt signals with the default gain value, thereby yielding amplified prompt signals that is then sent to the electro-acoustic transducer  14 . The electro-acoustic transducer  14  receives the amplified prompt signals, and reproduces prompt sounds according to the amplified prompt signals. The prompt sounds are used for alerting the listener to manually reduce a current gain value of the audio signal source  11 . 
         [0036]      FIG. 4  is a flowchart of a first preferred method for hearing protection in the ambient environment by utilizing the sound reproduction device of  FIG. 2 . In step S 40 , the amplitude sampling module  160  receives the digital audio signals from the audio ADC  15 , and samples the digital audio signals to obtain the plurality of sampled amplitude values of the digital audio signals. 
         [0037]    In step S 41 , the gain obtaining module  161  obtains the default gain value from the storage unit  17 . 
         [0038]    In step S 42 , the energy computing module  162  computes the actual audio energy of the digital audio signals within the predetermined time period according to the default gain value and the sampled amplitude values sampled within the predetermined time period. 
         [0039]    Simultaneously with step S 42 , in step S 43 , the microphone  19  collects the ambient noises from the ambient environment, and generate the analog noise signals. 
         [0040]    In step S 44 , the noise ADC  20  converts the analog noise signals to the digital ambient noises. 
         [0041]    In step S 45 , the noise processing module  163  computes the noise level according to the digital noise signals converted by the noise ADC  20 . 
         [0042]    In step S 46 , the noise processing module  163  reads the audio reference energy corresponding to the noise level from the noise level-audio energy index, or alternatively computes the audio reference energy. 
         [0043]    In step S 47 , the noise processing module  163  compares the actual audio energy with the audio reference energy, detects whether the actual audio energy reaches the audio reference energy. If the actual audio energy does not reach the audio reference energy, the procedure turns to start. 
         [0044]    When the actual audio energy reaches the audio reference energy, in step S 48 , the noise processing module  163  generates the hearing protect signal. 
         [0045]    In step S 49 , when the hearing protection module  164  receives the hearing protect signal, the hearing protection module  164  automatically changes the default gain value to the reduced gain value, signals the gain amplifier  18  to amplify the analog audio signals received from the audio signal source  11  by the reduced gain value, and updates the default gain value stored in the storage unit  17  with the reduced gain value, then the procedure turns to start. 
         [0046]      FIG. 5  is a schematic diagram of a hardware infrastructure of the sound reproduction device for hearing protection in accordance with a second preferred embodiment of the present invention. The sound reproduction device  50  includes a connector  52 , a hearing protection unit  53 , and an electro-acoustic transducer  54 . The sound reproduction device  50  receives the analog audio signals from the audio signal source  11  via the connector  52 , and sends the analog audio signals to the hearing protection unit  53  and the electro-acoustic transducer  54  respectively. 
         [0047]    The hearing protection unit  53  converts the analog audio signals to digital audio signals, computes the audio energy of the digital audio signals within the predetermined time period, and when the audio energy reaches the predetermined value, reproduces the prompt indicator to alert the listener to manually reduce the current gain value of the audio signal source, thus, preventing hearing impairment of the listener. The prompt indicator is selected from the group consisting of visual indicator and acoustical indicator. 
         [0048]    The electro-acoustic transducer  54  reproduces sounds corresponding to the analog audio signals. The electro-acoustic transducer  54  may be an earphone or a speaker. 
         [0049]      FIG. 6  is a block diagram of a hardware infrastructure of the sound reproduction device  50  of  FIG. 5  in accordance with the second preferred embodiment. The hearing protection unit  53  includes an audio ADC  65 , a processing unit  66 , a storage unit  67  and an alarm unit  68 . The alarm unit  68  may be an acoustical indicating device such as a buzzer, or a visual indicating device such as an LED (light-emitting diode). 
         [0050]    The audio ADC  65  receives the analog audio signals from the audio signal source  11  via the connector  52 , converts the analog audio signals to the digital audio signals, and sends the digital audio signals to the processing unit  66 . 
         [0051]    Referring to  FIG. 7 , the processing unit  66  includes an amplitude sampling module  660 , a gain obtaining module  661 , an energy computing module  662 , a noise processing module  663 , and a hearing protection module  664 . 
         [0052]    The amplitude sampling module  660  receives the digital audio signals from the audio ADC  65 , samples the digital audio signals at a predetermined frequency, and obtains a plurality of sampled amplitude values of the digital audio signals. 
         [0053]    The energy computing module  661  periodically computes an audio energy within the predetermined time period by applying a formula as follows: Q=[Σ(mi) 2 /N] 1/2 *T, wherein Q represents the actual audio energy, mi presents the sampled amplitude values sampled within the predetermined time period, N represents a count of the sampled amplitude values sampled within the predetermined time period, and i denotes an identifier of the sampled amplitude value. 
         [0054]    The hearing protection unit  63  further includes a microphone  60  and a noise ADC  69 . The microphone  60  is configured for collecting ambient noises, and generating analog noise signals. The noise ADC  60  is configured for converting the analog noise signals to digital noise signals. 
         [0055]    The noise processing module  663  computes the noise level according to the digital noise signals, and obtains the audio reference energy corresponding to the noise level. In a preferred method, the noise processing module  663  subtracts the predetermined noise level from the noise level to obtain the margin, divides the margin by the predetermined noise level to obtain the changed ratio i.e., changed ratio=(noise level−predetermined noise level)/predetermined noise level, and multiplies the changed ratio with the predetermined audio energy to obtain the audio reference energy. 
         [0056]    In an alternative preferred method, the hearing protection unit  63  further includes a storage unit  67  for storing the noise level-audio energy index. The noise level-audio energy index is the table that lists the audio reference energy corresponding to noise level ranges. The noise processing module  663  reads the noise level-audio energy index to obtain the audio reference energy corresponding to the noise level. 
         [0057]    The noise processing module  663  compares the actual audio energy with the audio reference energy, and generates a hearing protect signal when the actual audio energy reaches the audio reference energy. 
         [0058]    The hearing protection module  664 , when receiving the hearing protect signal, signals the alarm unit  68  to output prompt information. The prompt information is used for alerting the listener to manually reduce the current gain value of the audio signal source  11 , thus, preventing hearing impairment of the listener. 
         [0059]    In a third preferred embodiment, referring to  FIG. 8 , the difference between the third embodiment and the second embodiment is that the hearing protection unit  83  of the third embodiment does not include the alarm unit  68 , and a processing unit  86  and an electro-acoustic transducer  84  is adopted to perform the same functions of the alarm unit  68 . 
         [0060]    The processing unit  86  includes an amplitude sampling module  860 , a gain obtaining module  861 , an energy computing module  862 , and a noise processing module  863 , which respectively performs the same functions as the amplitude sampling module  160 , the gain obtaining module  161 , the energy computing module  162 , and the noise processing module  163  of the processing unit  16  in the first and second embodiment. 
         [0061]    The processing unit  86  further includes a hearing protection module  864 . The hearing protection module  864 , when receiving the hearing protect signal, sends the prompt signals to the electro-acoustic transducer  84 . The electro-acoustic transducer  84  reproduces prompt sounds corresponding to the prompt signals. 
         [0062]    It is understood that the invention may be embodied in other forms without departing from the spirit thereof. Thus, the present examples and embodiments are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.