Abstract:
The present invention relates to a hearing protection method, includes steps of: obtaining digital audio signals from an audio signal source; sampling the digital audio signals and obtaining a plurality of amplitude values; calculating an audio energy within a predetermined time period according to the amplitude values sampled in the predetermined time period; determining whether the audio energy reaches a predetermined value; and generating a hearing protect signal when the audio energy reaches the predetermined value, thereby protecting users&#39; hearing. The present invention also provides a corresponding sound output device for hearing protection.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is related to commonly-assigned copending application entitled, “SOUND OUTPUT DEVICE AND METHOD FOR HEARING PROTECTION”, filed on Dec. 5, 2006. Disclosure of the above identified application is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a sound output device and a method for hearing protection, and particularly, to a sound output device and method for automatically reducing a current gain value or enables an alarm, when an audio energy level of digital audio signals received from an audio signal source reaches a predetermined value. 
         [0004]    2. Description of Related Art 
         [0005]    Developments in the digital data technology have made portable audio devices (such as MP3 players) become popular among people. When environmental noise external of the portable audio device is loud or when a favorite song is played, a user commonly increases a volume of a portable device. However users all have a physiological hearing threshold, i.e., loudness discomfort level (LDL). If the user is directly exposed to a noise volume level that is larger than the user&#39;s LDL for a long time, hearing of the user may be impaired. 
         [0006]    In order to solve the problems mentioned, there is a common gain control system available in the market. The gain control system and method provide a gain value limit, and prevent the user from adjusting the gain value beyond the gain value limit. However, the system and method is rigid and not user friendly. 
         [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 output device and method for hearing protection. The sound output device and method are for receiving digital audio signals from an audio signal source, computing an audio energy level within a predetermined time period, and automatically changing a current gain value or outputting prompt sounds when the audio energy level reaches a predetermined value. 
         [0009]    The sound output device includes an interface, a DAC and a processing unit. The interface is configured for attaching to an audio signal source. The DAC is configured for receiving digital audio signals from the audio signal source via the interface, and converting the digital audio signals to analog audio signals. The processing unit receives the digital audio signals from the audio signal source via the interface. The processing unit includes an amplitude sampling module, an energy computing module and a hearing protection module. The amplitude sampling module samples the digital audio signals at a predetermined frequency, and obtains a plurality of amplitude values of the sampled digital audio signals. The energy computing module periodically computes an audio energy within a predetermined time period according to the amplitude values sampled in the predetermined time period. The hearing protection module determines whether the audio energy reaches a predetermined value, and generates a hearing protect signal when the audio energy reaches the predetermined value. 
         [0010]    The hearing protect method includes the steps of: receiving digital audio signals from an audio signal source; converting the analog audio signals to digital audio signals; sampling the digital audio signals to obtain a plurality of amplitude values; computing an audio energy within a predetermined time period according to the amplitude values sampled in the predetermined time period; determining whether the audio energy reaches a predetermined value; and generating a hearing protect signal when the audio energy reaches the predetermined value. 
         [0011]    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 
         [0012]      FIG. 1  is a schematic diagram of a sound output device for hearing protection in accordance with a preferred embodiment of the present invention; 
           [0013]      FIG. 2  is a block diagram of a hardware infrastructure of the sound output device for hearing protection of  FIG. 1 ; 
           [0014]      FIG. 3  is a schematic diagram of main function modules of a gain managing unit of  FIG. 2 ; 
           [0015]      FIG. 4  is a flowchart of a preferred method for hearing protection by utilizing the sound output device of  FIG. 2 ; 
           [0016]      FIG. 5  is a schematic diagram of a hardware infrastructure of a sound output device for hearing protection in accordance with an alternative embodiment of the present invention; and 
           [0017]      FIG. 6  is a schematic diagram of main function modules of a gain managing unit of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    In the following embodiments, for simplicity, a hearing protection function incorporated in a sound output device, such as an earphone, is depicted. The following detailed description of the embodiments is made with reference to the attached drawings. 
         [0019]      FIG. 1  is a schematic diagram of a hardware infrastructure of a sound output device for hearing protection in accordance with a preferred embodiment of the present invention. The sound output device  10  includes an interface  12 , a hearing protection unit  13 , a digital-to-analog converter (DAC)  15 , and a sound transducer  14 . The sound output device  10  receives digital audio signals from an audio signal source  11  via the interface  12 , and sends the digital audio signals to the hearing protection unit  13  and the DAC  15  respectively. The audio signal source  11  can be a music player, a radio player, a TV set, and so on. 
         [0020]    The DAC  15  converts the digital audio signals to analog audio signals, and sends the analog audio signals to the hearing protection unit  13 . 
         [0021]    The hearing protection unit  13  calculates an audio energy of the digital audio signals within a predetermined time period. If the audio energy reaches a predetermined value, the hearing protection unit  13  may automatically change a current gain value to a reduced gain value, or outputs prompt signals to the sound transducer  14  to reproduce prompt sounds corresponding to the prompt signals. The prompt sounds alerts a user to manually change the current gain value to the reduced gain value, thus, preventing hearing impairment of the user. 
         [0022]    The sound transducer  14  further reproduces sounds corresponding to the analog audio signals converted by the DAC  15 . 
         [0023]      FIG. 2  is a block diagram of a hardware infrastructure of the sound output device for hearing protection of  FIG. 1 . The hearing protection unit  13  includes a processing unit  17  and a gain amplifier  18 . The processing unit  17  includes a gain managing unit  16  and a storage unit  19 . The storage unit  19  stores a default gain value. The storage unit  19  may be a flash storage, a hard disk driver, and the like. The processing unit  17  controls elements of the hearing protection unit  13 , i.e., the gain managing unit  16 , the gain amplifier  18  and the storage unit  19 . 
         [0024]    The DAC  15  receives the digital audio signals from the audio signal source  11  via the interface  12 , converts the digital audio signals to analog audio signals, and sends the analog audio signals to the gain amplifier  18 . 
         [0025]    Referring to  FIG. 3 , the gain managing unit  16  includes an amplitude sampling module  160 , a gain obtaining module  161 , an energy computing module  162 , a hearing protection module  163 , and a gain adjusting module  164 . The amplitude sampling module  160  samples the digital audio signals received from the audio signal source  11  at a predetermined frequency continuously, and obtains a plurality of amplitude values of the sampled digital audio signals. 
         [0026]    The gain obtaining module  161  reads the default gain value from the storage unit  19 . The energy computing module  162  periodically calculates an audio energy within a predetermined time period by: Q=[Σ(mi*V) 2 /N] 1/2 *T, where V represents the default gain value, T represents the predetermined time period, Q represents the audio energy of the digital audio signals within the predetermined time period, N represents a count of the amplitude values sampled in the predetermined time period, i is any natural number from 1 to N, and mi represents the amplitude values sampled in the predetermined time period. 
         [0027]    The hearing protection module  163  determines whether the audio energy reaches the predetermined value, and if the audio energy reaches the predetermined value, generates a hearing protect signal, and sends the hearing protect signal to the gain adjusting module  164 . 
         [0028]    The gain adjusting module  164  is configured for receiving the hearing protect signal from the hearing protection module  163 . After receiving the hearing protect signal, the gain adjusting module  164  automatically changes the default gain value to reduced gain value, and signals the gain amplifier  18  to amplify the analog audio signals received from the DAC  15  according to the reduced gain value, thereby yielding amplified analog audio signals. The gain adjusting module  164  updates the default gain value stored in the storage unit  19  with the reduced gain value, and sends the amplified analog audio signals to the sound transducer  14 . 
         [0029]      FIG. 4  is a flowchart of a preferred method for hearing protection by utilizing the sound output device of  FIG. 2 . In step S 40 , the gain managing unit  16  receives the digital audio signals from the audio signal source  11  via the interface  12 . 
         [0030]    In step S 41 , the amplitude sampling module  160  samples the digital audio signals, and obtains a plurality of amplitude values of the sampled digital audio signals. 
         [0031]    In step S 42 , the gain obtaining module  161  reads the default gain value from the storage unit  19 . 
         [0032]    In step S 43 , the energy computing module  161  computes the audio energy within the predetermined time period according to the default gain value and the plurality of amplitude values sampled in the predetermined time period. 
         [0033]    In step S 44 , the hearing protection module  163  determines whether the audio energy reaches the predetermined value. 
         [0034]    If the audio energy does not reach the predetermined value, the procedure turns to step S 41 ; if the audio energy reaches the predetermined value, in step S 45 , the hearing protection module  163  generates the hearing protect signal, and sends the hearing protect signal to the gain adjusting module  164 . 
         [0035]    In step S 46 , after receiving the hearing protect signal, the gain adjusting module  164  automatically changes the default gain value to the reduced gain value, and updates the default gain value stored in the storage unit  19  with the reduced gain value. 
         [0036]    In step S 47 , the gain adjusting module  164  signals the gain amplifier  18  to amplify the analog audio signals received from the DAC  15  according to the reduced gain value, thereby yielding amplified analog audio signals; the gain amplifier  18  sends the amplified analog audio signals to the sound transducer  14 . 
         [0037]    In step S 48 , the sound transducer  14  receives the amplified analog audio signals, and reproduces sounds corresponding to the amplified analog audio signals. 
         [0038]      FIG. 5  is a block diagram of a hardware infrastructure of the sound output device for hearing protection in accordance with an alternative embodiment of the present invention. The sound output device  50  includes an interface  52 , a hearing protection unit  53 , a DAC  55 , and a sound transducer  54 . The hearing protection unit  53  includes a processing unit  57  and an alarm unit  58 . The alarm unit  58  may be an acoustical alarm unit such as a buzzer, or a visual alarm unit such as an LED (light-emitting diode). 
         [0039]    The DAC  55  receives the digital audio signals from the audio signal source  11  via the interface  52 , converts the digital audio signals to analog audio signals, and sends the analog audio signals to the sound transducer  54 . The sound transducer  54  reproduces sounds corresponding to the analog audio signals. 
         [0040]    The processing unit  57  receives the digital audio signals from the audio signal source  11  via the interface  52 . Referring to  FIG. 6 , the processing unit  57  includes an amplitude sampling module  570 , an energy computing module  571  and a hearing protection module  572 . 
         [0041]    The amplitude sampling module  570  samples the digital audio signals at a predetermined frequency, and obtains a plurality of amplitude values of the sampled digital audio signals. 
         [0042]    The energy computing module  571  periodically calculates an audio energy within the predetermined time period by: Q=[Σ(mi) 2 /N] 1/2 *T, wherein T represents the predetermined time period, Q represents the audio energy of the digital audio signals within the predetermined time period, N represents a count of the amplitude values sampled within the predetermined time period, i is any natural number from 1 to N, and mi represents the amplitude values sampled within the predetermined time period. 
         [0043]    The hearing protection module  572  determines whether the audio energy reaches the predetermined value, and if the audio energy reaches the predetermined value, generates a hearing protect signal, and sends the hearing protect signal to the alarm unit  58 . 
         [0044]    After receiving the hearing protect signal, the alarm unit  58  outputs prompt sounds for alerting the user to change the current gain value. The prompt sounds may be acoustical reminding signals or visual alarm signals. 
         [0045]    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.