This need for a new generation of ‘green’ microphones leads to embedding the capability for waking up the rest of the system as soon as a voice activity is detected, possibly once a keyword has been spotted, while enhancing the recording quality with high sensitivity in far field and near field environments.
The combination of a complete analogue-to-digital converter (ADC) with a voice processing DSP has, Dolphin asserts, reached its limits for lowering power consumption. Voice detection by a DSP in always-listening mode is proving to be unsatisfactory for IoT applications powered by small batteries or even on a smartphone. Green microphones fill the low-power gap by reducing by a ratio of at least five, the power consumption in always-listening mode.
To increase battery life far beyond any current solution, and to improve the sound recording quality, such green microphones require a new generation of ultra-low power voice triggers and fast response ADC modulators. The DSP can then be embedded in the same SoC as the sound signal buffer and perform the ADC decimation and filtering functions.