KWS: Labelling a 'None' Class?

Hello,

First of all, thank you so much for providing the SpeechBrain toolkit!

A little bit of context:

I have a collection of speech data from users with speech impediments and I wanted to train the data on SpeechBrain. The data ranges from single words to sentences and I need to identify a single word (keyword) from the audio data. The problem is that the majority of my data samples do not have any keyword (from what I’ve defined a keyword to be).

My Question:

I noticed in the SpeakerIDfromScratch tutorial that we can add labels for tasks such as keyword spotting, but I’m not sure how to add a label if the audio data has no matching keyword.

How can I create a class to label the data preparation script for samples which have no match?

Any guidance is greatly appreciated.