Audio output system for a vehicle

1. An audio output system for a vehicle, comprising:

a volume setting device for setting a volume of an audio signal;

an audio input for providing an audio input signal from an audio source;

a warning tone device for providing a warning tone signal;

an audio-level measuring device for measuring an audio level at the audio input; and

a control unit,

wherein the audio-level measuring device is configured to limit a maximum audio level of the audio input signal to a predefined first threshold value as a function of a set volume, and

wherein the control unit is configured to control an audio output signal on the basis of the warning tone signal, the audio input signal and the set volume,

wherein the control unit is configured to output an audible or visual notification if the audio input signal present at the audio input has no audio level.

2. The audio output system as claimed in claim 1 , wherein the control unit is configured to reduce the maximum audio level of the audio input signal or to mute the audio input signal if the warning tone device is providing a warning tone signal.

3. The audio output system as claimed claim 2 , wherein the control unit is configured to limit a rate of change of the audio level of the audio output signal if the audio input signal has been reduced because of a warning tone signal.

4. The audio output system as claimed in claim 1 , wherein the control unit is configured to generate an audio reference signal in order to determine an audio output level required by a user.

5. The audio output system as claimed in claim 4 , wherein the first predefined threshold value is higher than a user-set audio level of the audio input signal.

6. The audio output system as claimed in claim 1 , wherein the control unit is configured to compare the audio level measured at the audio input with a standard input level set by the user, and thereby to determine the first predefined threshold value.

7. The audio output system as claimed in claim 6 , wherein the first predefined threshold value is higher than the user-set audio level of the audio input signal.

8. The audio output system as claimed in claim 1 , wherein the control unit is configured to limit the audio level of the audio output signal to a second threshold value.

9. The audio output system as claimed in claim 1 , wherein the audio source comprises a plurality of input sources.

10. A vehicle comprising an audio output system as claimed in claim 1 .

11. A method for audio output for a vehicle, comprising:

setting a volume for an audio signal;

measuring an audio level of an audio input signal at an audio input by an audio-level measuring device;

limiting by the audio-level measuring device a maximum audio level of the audio input signal to a first predefined threshold value as a function of a set volume;

controlling an audio output signal based on a warning tone signal, the audio input signal and the set volume; and

outputting an audible or visual notification if the audio input signal present at the audio input has no audio level.

12. A non-transitory computer program element which, when executed on a control unit of an audio output system, instructs the audio output system to carry out the method as claimed in claim 11 .

13. A non-transitory computer-readable storage medium on which the computer program element as claimed in claim 12 is stored.