LanguageModel

Hotword Detection is as cool as it sounds. What exactly is hotword detection? Hotword detection is a feature in which a device gets activated when it listens to a specific word or a phrase. You must have said “OK Google” or “Hey Cortana” or “Siri” or “Alexa” at least once in your lifetime. These all are hotwords which trigger the specific action attached to them. That specific action can be anything. Implementing hotword detection from scratch in SUSI Android is not an easy task. You have to define language model, train the model and do various other processes before implementing it in Android. In short, not feasible to implement that along with the code of our Android app. There are many open source projects on hotword detection and speech recognition. They already have done what we need and we can make use of it. One such project is Snowboy. According to Snowboy GitHub repo “Snowboy is a DNN based hotword and wake word detection toolkit.” Img src: https://snowboy.kitt.ai/ In SUSI Android App, we have used Snowboy for hotword detection with hotword as “susi” (pronounced as ‘suzi’). In this blog, I will tell you how Hotword detection is implemented in SUSI Android app. So, you can just follow the steps and you will be able to implement it in your application too or if you want to contribute in SUSI android app, it may help you a little in knowing the codebase better. Pre Processing before Implementation 1. Generating Hotword Model The start of implementation of hotword detection begins with creating a hotword model from snowboy website https://snowboy.kitt.ai/dashboard . Just log in and search for susi and then train it by saying “susi” thrice and download the susi.pmdl file. There are two types of models: .pmdl : Personal Model .umdl : Universal Model The personal model is specifically trained for you and is instantly available for you to download once you train the hotword by your voice. On the other hand, the Universal model is trained by minimum 500 hundred people and is only available once it is trained. So, we are going to use personal model for now since training of universal model is not yet completed. Img src: https://snowboy.kitt.ai/ 2. Adding some predefined native binary files in your app. Once you have downloaded the susi.pmdl file and you need to copy some already written native binary file in your app. In your assets folder, make a directory named snowboy and add your downloaded susi.pmdl file along with this file in it. Copy this folder and add it in your  /app/src/main/java folder as it is. These are autogenerated swig files. So, don’t change it unless you know what you are doing. Also, create a new folder in your /app/src/main folder called jniLibs and add these files to it. Implementation in SUSI Android App Check out the implementation of Hotword detection in SUSI Android App here You now have everything ready. Now you just need to implement some code in your…