# Pocketsphinx_KWS - Speech to Text

This plugin uses thresholds to listen for specific words. It is primarily meant to be used to listen for keywords or wakewords, although if you have an application with a very limited vocabulary (such as a robot that responds to "left", "right", "forward", and "stop") you can use it for the full vocabulary.

In Naomi, we will use it to listen for the wake word(s).

To activate this plugin, change your profile.yml file to set the passive listener engine like this:

keyword:
- NAOMI
- MAGICVOICE
passive_stt:
  engine: Pocketsphinx_KWS
Pocketsphinx_KWS:
    thresholds:
        naomi: -10
        magicvoice: -50

(notice that under the thresholds section, the keywords should be all lower case).

When you use this plugin, it will automatically create a vocabulary including a thresholds file called kws.thresholds. The thresholds file has a format like:

naomi   /1e-10/
magicvoice  /1e-50/

If you have defined thresholds in your profile, they will be used when creating the thresholds file. If any of your wake words are being activated accidentally too often, try increasing the threshold. If Naomi becomes too difficult to activate, try decreasing the threshold. The range of valid threshold levels is from negative eighty to eighty. I am working on a trainer called Pocketsphinx_KWS_Trainer. When it is available, you can use the recordings and verified transcripts to help select the best thresholds.

This also shares the "sphinx" acoustic model, so using the "Adapt Pocketsphinx" STT Trainer plugin is highly recommended for training Naomi to your voice.