Low power detection of a voice control activation phrase
View Patent ↗Methods of low power detection of an activation phrase are described. A microphone system comprises dedicated hardware logic for detecting a pre-defined activation phrase in an audio stream received via a microphone. If the pre-defined activation phrase is detected, the hardware logic sends a trigger signal to activate a module, such as a main speech detection module, which is external to the microphone system and which may be in a low power standby state.
1. A microphone system comprising a microphone and hardware logic configured to compare an audio stream received via the microphone with a pre-defined phrase and in response to partially detecting the pre-defined phrase in a first portion of the audio stream, to:
determine if a previous portion of the audio stream comprising a partially detected pre-defined phrase was stored;
in response to determining that the previous portion of the audio stream comprising a partially detected pre-defined phrase was not stored, to store the first portion of the audio stream;
in response to determining that the previous portion of the audio stream comprising a partially detected pre-defined phrase was stored, to compare the first portion of the audio stream and the stored previous portion of the audio stream; and
in response to detecting a match between the first portion of the audio stream and the stored previous portion of the audio stream, to send a trigger signal to activate a module external to the microphone system.
2. A microphone system according to claim 1 , further comprising an audio buffer arranged to store a second portion of the audio stream received via the microphone after a first portion of the audio stream comprising the pre-defined phrase.
3. A microphone system according to claim 1 , wherein the hardware logic is configured to divide a portion of detected audio into one or more component parts and to compare the component parts to one or more stored component parts of the pre-defined phrase.
4. A microphone system according to claim 1 , further comprising an amplifier configured to amplify the audio stream received via the microphone according to a gain parameter and to output the amplified audio stream to the hardware logic which is configured to detect the pre-defined phrase, and wherein the hardware logic is further configured, in response to detecting the pre-defined phrase, to send a signal to the amplifier to increase a value of the gain parameter.
5. A microphone system according to claim 4 , wherein the hardware logic is further configured to send a signal to the amplifier to reduce the value of the gain parameter in response to the module external to the microphone system entering a low power mode.
6. A microphone system according to claim 1 , further comprising an analogue to digital converter configured to convert the audio stream received via the microphone into a digital audio stream by sampling the received audio stream at a sample rate and a sample resolution and to output the digital audio stream to the hardware logic which is configured to detect the pre-defined phrase and wherein the hardware logic is further configured, in response to detecting the pre-defined phrase, to send a signal to increase the sample rate and/or sample resolution.
7. A microphone system according to claim 6 , wherein the hardware logic is further configured to send a signal to reduce the sample rate and/or sample resolution in response to the module external to the microphone system entering a low power mode.
8. A microphone system according to claim 1 , further comprising a memory arranged to store the pre-defined phrase, wherein the pre-defined phrase is an activation phrase for activating a module external to the microphone system.
9. A microphone system according to claim 8 , wherein the hardware logic is further configured, in response to detecting the pre-defined phrase, to update the stored pre-defined phrase using the detected pre-defined phrase.
10. A microphone system according to claim 1 , wherein the hardware logic is further configured, in response to partially detecting the pre-defined phrase, to send a portion of the audio stream comprising the partially detected pre-defined phrase to the module external to the microphone system.
11. A microphone system according to claim 1 , wherein the pre-defined phrase is a sample of a contextual sound.
12. A microphone system according to claim 1 , wherein the pre-defined phrase comprises one or more spoken words.
13. A microphone system according to claim 12 , wherein the pre-defined phrase is an activation phrase for a voice controlled computing device.
14. A microphone system according to claim 13 , wherein the module external to the microphone system is a main speech detection module and the main speech detection module is implemented by a processor in the voice controlled computing device.
15. A microphone system according to claim 12 , wherein the microphone system comprises two modes of operation and wherein
in a first mode of operation, the hardware logic is configured to detect a pre-defined phrase in an audio stream received via the microphone by dividing a portion of detected audio into one or more component parts and comparing the component parts to one or more stored component parts of the pre-defined phrase and in response to detecting the pre-defined phrase, to send a trigger signal to activate a first module external to the microphone system; and
in a second mode of operation, the hardware logic is configured to divide a portion of detected audio into one or more component parts and to provide the component parts to a second module external to the microphone system.
16. A microphone system according to claim 15 , wherein the first module external to the microphone system and the second module external to the microphone system are the same and the module is a main speech detection module.
17. A microphone system according to claim 15 , wherein the first module external to the microphone system is a main speech detection module and the second module external to the microphone system is a communications interface arranged to transmit the component parts to a remote phrase detection and recognition system.
18. A microphone system according to claim 1 , wherein the hardware logic is configured to continuously analyse the audio stream received via the microphone to detect the pre-defined phrase.
19. A method of operating a microphone system comprising:
detecting an audio stream from a microphone in the microphone system;
comparing the detected audio stream with a pre-defined phrase stored in dedicated hardware in the microphone system; and
in response to partially detecting the pre-defined phrase in a first portion of the audio stream;
determining if a previous portion of the audio stream comprising a partially detected pre-defined phrase was stored;
in response to determining that the previous portion of the audio stream comprising a partially detected pre-defined phrase was not stored, storing the first portion of the audio stream;
in response to determining that the previous portion of the audio stream comprising a partially detected pre-defined phrase was stored, comparing the first portion of the audio stream and the stored previous portion of the audio stream; and
in response to detecting a match between the first portion of the audio stream and the stored previous portion of the audio stream, sending a trigger signal to activate a module external to the microphone system.