Question

I’m a beginner in programming and I’m trying to build a simple application to display message box that shows what I tried to say using voice recognition. The problem is when I say “hello” for the first time, for example, no message box is displayed. If I try one more time, a correct message box is played. In the third time that I say “hello”, 2 message boxes are displayed. In the 4th time, 3 message boxes, and so on. Can anyone help with this problem?

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Speech.Recognition;

namespace Voices
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private SpeechRecognitionEngine sre;

        private void Form1_Load(object sender, EventArgs e)
        {
            sre = new SpeechRecognitionEngine();
            sre.SetInputToDefaultAudioDevice();

            Choices commands = new Choices();
            commands.Add(new string[] { "hello" });

            GrammarBuilder gb = new GrammarBuilder();
            gb.Append(commands);

            Grammar g = new Grammar(gb);
            sre.LoadGrammar(g);

            sre.RecognizeAsync(RecognizeMode.Multiple);


            sre.SpeechRecognized += (s, args) =>
            {
                foreach (RecognizedPhrase phrase in args.Result.Alternates)
                {
                    if (phrase.Confidence > 0.9f)
                        sre.SpeechRecognized += new EventHandler<SpeechRecognizedEventArgs>(sre_SpeechRecognized);
                }
            };

        }

        void sre_SpeechRecognized(object sender, SpeechRecognizedEventArgs e)
        {
            switch (e.Result.Text)
            {
                case "hello":
                    MessageBox.Show(e.Result.Text);                    
                    break;
            }
        }       
    }
}

Answer 1

Following code is the reason you get multiple message boxes:

sre.SpeechRecognized += (s, args) =>
{
    foreach (RecognizedPhrase phrase in args.Result.Alternates)
    {
        if (phrase.Confidence > 0.9f)
            sre.SpeechRecognized += new EventHandler<SpeechRecognizedEventArgs>(sre_SpeechRecognized);
    }
};

Everytime SpeechRecognized is raised, it registers to the same event with the same eventhandler.

It should register to the event only once.

I guess what you want to do is following:

if (phrase.Confidence > 0.9f)
    sre_SpeechRecognized(s, args);