Sequence Discriminative Training for Deep Learning based Acoustic Keyword Spotting
TABLE III: Performances of the Sub-word Level CTC with or without the wb Unit.
['Keyword Length', 'wb', 'EER']
Those keywords which contain less than 6 phones are considered as short keywords, otherwise the keywords are long. Thus, the keyword set is divided into two parts to show the modeling effect clearly. Both short keywords and long keywords yield performance improvements, namely 50% relative EER reduction for short keywords and 42% EER reduction for long keywords. Besides, the performance of long keywords consistently beats that of short keywords. This is because the phone sequences of short keywords are more likely being substrings of other words or phrases, which will cause a higher false alarm rate. By introduction of wb, the problem is alleviated.