In the new industry of smart home appliances, there is not only the problem of inconsistent standards, but also the problem of speech recognition system to filter the background noise.
According to the national mandatory standards: washing noise limit value of washing machine is 62 decibels, dehydration noise limit value is 72 decibels; Volume in the refrigerator below 250 liters, noise limit 45-47 decibels, more than 250 liters of noise limit 48-55 decibels; According to the rated cooling capacity, the noise is 40-68 decibels; The noise limit for microwave ovens is 68 decibels. The noise (sound power level) of the range hood is not more than 74dB when it is running at the highest speed under rated voltage and rated frequency.
The background noise of the use environment should be less than 50dB. The greater the background noise, the lower the speech recognition rate. At this time, it is necessary to do noise reduction and echo elimination processing for these background sounds.
The dual-MIC front-end circuit is built into the dual-MIC noise reduction and echo cancellation scheme of Light Life Technology (enhanced version of offline voice scheme). The independent DSP does the noise reduction and echo cancellation calculation, and supports the far field identification of 3-5 meters.