Existing ANC headsets have active noise reduction circuitry and a power supply in the headset. Alternate ANC headsets rely on ANC circuitry in the player and have non-standard connectors meaning that they cannot be used with any other players. An audio headset ( 90 ) having an encoder ( 54 ) and active noise cancellation audio processing device ( 80 ) having a decoder ( 32 ) are described. The encoder ( 54 ) enables the audio headset to be used in enhanced (ANC) mode when connected to a compatible audio processing device and in normal mode when connected to a non-compatible audio processing device since a standard audio jack plug can be used. Similarly the decoder ( 62 ) in the active noise cancellation audio processing device ( 80 ) enables the active noise cancellation audio processing device to be used in enhanced mode when connected to a compatible audio headset and in normal mode connected to a non-compatible audio headset since a standard audio socket can be used.
1. An audio headset compatible with active noise cancelling audio processing devices and audio processing devices without active noise cancelling, the audio headset comprising:
at least one microphone for measuring noise;
an encoder for encoding a noise measurement signal received from the microphone via an input of the encoder, to produce an encoded noise measurement signal; and
a connector for connecting the audio headset to an audio processing device, the connector having a terminal for carrying a microphone signal,
wherein the audio headset is configured to detect if a device to which the audio headset is connected to is an active noise cancelling audio processing device or an audio processing device without active noise cancelling, wherein the audio headset is operable when connected to the active noise cancelling audio processing device to output the encoded noise measurement signal via the terminal and to receive a combined audio and anti-noise signal from the active noise cancelling audio processing device; and
when connected to the audio processing device without active noise cancelling:
to output one of a null signal and an unencoded signal from the at least one microphone via the terminal; and
to receive an audio signal from the audio processing device without active noise cancelling.
2. The audio headset of claim 1 , further comprising at least one switch coupled to a further input of the encoder, and wherein the audio headset is operable to output an encoded signal reflecting a state of the at least one switch and the encoded microphone signals.
3. The audio headset according to claim 1 , wherein a power supply for the encoder is supplied via the terminal.
4. The audio headset according to claim 1 , wherein the connector comprises a 3.5 mm audio plug.
5. The audio headset according to claim 1 , wherein the connector comprises
a further terminal for receiving an identifying signal for identifying a compatible active noise cancelling audio processing device, and
the encoder comprises
a further input coupled to the further terminal,
wherein the encoder is operable to receive the identifying signal via the further terminal and enable or disable encoding according to a content of the identifying signal.
6. The audio headset of claim 1 , wherein the encoder is operable to send an audio headset identifying signal via the terminal of the connector.
7. The audio headset of claim 6 wherein the audio headset identifying signal has a frequency greater than 20 KHz.
8. The audio headset of claim 6 wherein the audio headset identifying signal includes audio headset calibration parameters.
9. An active noise cancelling audio processing device comprising
a connector for connecting the audio processing device to an audio headset, the connector having a terminal for carrying a microphone signal,
an active noise cancelling processor,
a decoder having an input coupled to the terminal and an output coupled to the active noise cancelling processor; wherein the audio processing device is operable when connected to an audio headset adapted for active noise cancellation
to receive an encoded noise measurement signal from the audio headset via the terminal;
to use the decoder to decode the encoded noise measurement signal; and
to use the active noise cancelling processor to generate a combined audio and anti-noise signal; and
when connected to an audio headset not adapted for active noise cancelling:
to receive one of an unencoded microphone signal and a null signal from the audio headset via the terminal; and
to generate an audio signal not including an anti-noise signal,
wherein the audio processing device is configured to provide a notification to the audio headset to enable the audio headset to determine if the audio processing device includes the active noise cancelling processor.
10. The active noise cancelling audio processing device of claim 9 , wherein the connector comprises a 3.5 mm audio socket.
11. The active noise cancelling audio processing device of claim 9 , wherein the decoder is operable to receive an audio headset identifier signal via the terminal and to enable or disable decoding of the input signal according to a content of the audio headset identifier signal.
12. The active noise cancelling audio processing device of claim 9 , the connector comprising a further terminal for carrying a headphone signal and an identifying signal, and wherein
a further output of the decoder is coupled to the further terminal, and
the decoder is operable to transmit an identifying signal to a compatible audio headset.
13. An active noise cancellation system comprising:
the audio headset of claim 1 connectable, by their respective connectors, to an active noise cancelling audio processing device including;
a connector for connecting the audio processing device to the audio headset, the connector having a terminal for carrying a microphone signal,
an active noise cancelling processor,
a decoder having an input coupled to the terminal and an output coupled to the active noise cancelling processor; wherein the audio processing device is operable when connected to an audio headset adapted for active noise cancellation
to receive an encoded noise measurement signal from the audio headset via the terminal;
to use the decoder to decode the encoded noise measurement signal; and
to use the active noise cancelling processor to generate a combined audio and anti-noise signal; and
when connected to an audio headset not adapted for active noise cancelling:
to receive one of an unencoded microphone signal and a null signal from the audio headset via the terminal; and
to generate an audio signal not including an anti-noise signal.
14. A mobile phone comprising the active noise cancelling audio processing device of claim 9 .
15. An MP3 player comprising the active noise cancelling audio processing device of claim 9 .