Headphone device, audio device, and method for operating a headphone device

1. A headphone device, comprising:

an electric input terminal for receiving an electric audio signal;

an electric energy storage device;

a charging device coupled to the electric input terminal and the electric energy storage device and configured to charge the electric energy storage device with electric energy from the electric audio signal;

an audio processing device configured to receive the electric audio signal and to generate an electric audio output signal based on the received electric audio signal; and

an electroacoustic transducer coupled to the audio processing device for outputting an acoustic signal based on the generated electric audio output signal; and

wherein the audio processing device is powered by electric energy from the electric energy storage device; and

wherein the audio processing device is configured to control a volume of the electric audio output signal at a constant level depending on a charging level of the electric energy storage device to compensate for variations in volume output of the headphone device due to a varying amount of energy derived from the received electric audio signal for charging the electric energy storage device.

2. The headphone device according to claim 1 , comprising:

a microphone providing an electric audio input signal based on an acoustic signal received by the microphone; and

wherein the audio processing device is coupled to the microphone and configured to generate the electric audio output signal based on the electric audio input signal from the microphone such that ambient noise is at least partially compensated by the acoustic signal at an output of the electroacoustic transducer.

3. The headphone device according to claim 1 , comprising at least one of:

a high pass filtering device coupled between the electric input terminal and the charging device and having a first cutoff frequency; and

a low pass filtering device coupled between the electric input terminal and the charging device and having a second cutoff frequency.

4. The headphone device according to claim 3 , wherein the first cutoff frequency is in a range from 16 kHz to 22 kHz, and the second cutoff frequency is in a range from 16 Hz to 40 Hz.

5. The headphone device according to claim 4 , wherein the first cutoff frequency is 20 kHz.

6. The headphone device according to claim 4 , wherein the second cutoff frequency is 20 Hz.

7. The headphone device according to claim 1 , comprising:

an electric illumination device powered by electric energy from the electric energy storage device.

8. The headphone device according to claim 1 , wherein:

the electric audio signal is received via an electric output terminal of an audio device; and

the electric audio signal comprises a first component from an audio source of the audio device and a second component from an audio energy supply device of the audio device, the second component having at least one of a frequency above a first frequency value or a frequency below a second frequency value.

9. A method for operating a headphone device, comprising:

receiving an electric audio signal at the headphone device;

charging an electric energy storage device of the headphone device with electric energy from the electric audio signal;

powering an audio processing device with electric energy from the electric energy storage device;

generating, with the audio processing device, an electric audio output signal based on the received electric audio signal;

outputting, with an electroacoustic transducer, an acoustic signal based on the generated electric audio output signal; and

controlling a volume of the electric audio output signal at a constant level depending on a charging level of the electric energy storage device to compensate for variations in volume output of the headphone device due to a varying amount of energy derived from the received electric audio signal for charging the electric energy storage device.

10. The method according to claim 9 , comprising:

generating the electric audio output signal based on an electric audio input signal from a microphone such that ambient noise is at least partially compensated by the acoustic signal at an output of the electroacoustic transducer.

11. The method according to claim 9 , comprising:

charging the electric energy storage device only with components of the electric audio signal having a frequency above a first frequency value or components of the electric audio signal having a frequency below a second frequency value.

12. The method according to claim 9 , comprising:

powering an electric illumination device of the headphone device by electric energy from the electric energy storage device.