The LexiconRuntime provides a few useful events that you can subscribe to:

OnSpeechStatusUpdated	Called when the speech to text status changes (e.g. silence vs sending)
OnSpeechToTextResults	Called whenever speech to text results are updated, including intermediary results
OnKeywordDetected	Called whenever speech to text recognizes a keyword
OnLexiconResults	Called when Lexicon has finished processing all the results for an utterance

To subscribe to these events, create an instance of the appropriate delegate and assign it to the event:

using System.Collections.Generic;
using UnityEngine;
using Mixspace.Lexicon;

public class LexiconRuntimeEvents : MonoBehaviour
{
    void OnEnable()
    {
        LexiconRuntime.OnSpeechStatusUpdated += OnSpeechStatusUpdated;
        LexiconRuntime.OnSpeechToTextResults += OnSpeechToTextResults;
        LexiconRuntime.OnKeywordDetected += OnKeywordDetected;
        LexiconRuntime.OnLexiconResults += OnLexiconResults;
    }

    void OnDisable()
    {
        LexiconRuntime.OnSpeechStatusUpdated -= OnSpeechStatusUpdated;
        LexiconRuntime.OnSpeechToTextResults -= OnSpeechToTextResults;
        LexiconRuntime.OnKeywordDetected -= OnKeywordDetected;
        LexiconRuntime.OnLexiconResults -= OnLexiconResults;
    }

    void OnSpeechStatusUpdated(LexiconSpeechStatus status)
    {
        Debug.Log("Speech Status: " + status);
    }

    void OnSpeechToTextResults(LexiconSpeechResult speechResult)
    {
        if (speechResult.IsFinal)
        {
            Debug.Log("Speech Transcript: " + speechResult.Transcript);
        }
    }

    void OnKeywordDetected(LexiconSpeechResult.KeywordResult keywordResult)
    {
        Debug.Log("Found Keyword: " + keywordResult.Keyword);
    }

    void OnLexiconResults(List<LexiconRuntimeResult> results)
    {
        foreach (LexiconRuntimeResult result in results)
        {
            Debug.Log("Matched Intent: " + result.Intent.ActionName + ", confidence: " + result.Confidence);
        }
    }
}