To add speech on Air Tap gesture, we can instantiate the TextToSpeechManager and call the SpeakText() method. To integrate speech while doing Air Tap on the Lenses, navigate to the LensGestureHandler class and add the following code snippet while tapped is true.

if (isTapped)
{
     ....
    var soundManager= GameObject.FindWithTag("SoundManager"); 

    TextToSpeechManager tt = 
         soundManager.GetComponent<TextToSpeechManager>();
    tt.SpeakText("The HoloLens display is basically a set of 
         transparent lenses placed just in front of the eyes.");
}