System.Speech.Recognition accuracy with DictationGrammar

Question

hello I'm trying to find free and useful speech recognition for C# windows application. I've tried System.Speech.Recognition; but if phrase or word is not pre-recorded and I want use DictationGrammar sometimes I have to say 20 times same phrase or word, but 20 times I have wrong recognition results. So I do not mean that it does not work well, but it doesn't work for my case. So if I can somehow to make it work better, need your help here:

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

//using System.Speech;
using System.Speech.Recognition;

public class Program
{
    public static void Main()
    {

        SpeechRecognitionEngine recognizer = new SpeechRecognitionEngine();
        Grammar dictationGrammar = new DictationGrammar();
        recognizer.LoadGrammar(dictationGrammar);

        try
        {

            recognizer.SetInputToDefaultAudioDevice();
            RecognitionResult result = recognizer.Recognize();
            Console.WriteLine (result.Text);
        }
        catch (InvalidOperationException exception)
        {
            Console.WriteLine (String.Format("Could not recognize input from default aduio device. Is a microphone or sound card available?\r\n{0} - {1}.", exception.Source, exception.Message));
        }
        finally
        {
            recognizer.UnloadAllGrammars();
        }

        Console.Read();

    }

}

I have tried before Google Speech Recognition with Python and it was 95% correct at least, more then enough to say, that for me this is enough, but apparently if I do not have a key it is not available for free:

System.Net.WebException: The remote server returned an error: (403) Forbidden.
   at System.Net.HttpWebRequest.GetResponse()
   at GoogleRequest.Program.Main(String[] args) in C:\FOLDER\02_WORKFILE\Program.cs:line 36

Says that API keys are only for Chromium development and not to ask questions on this list https://www.chromium.org/developers/how-tos/api-keys Maybe there is some other way to use it:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net;
using System.IO;

namespace GoogleRequest
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {

                FileStream fileStream = File.OpenRead("good-morning-google.flac");
                MemoryStream memoryStream = new MemoryStream();
                memoryStream.SetLength(fileStream.Length);
                fileStream.Read(memoryStream.GetBuffer(), 0, (int)fileStream.Length);
                byte[] BA_AudioFile = memoryStream.GetBuffer();
                HttpWebRequest _HWR_SpeechToText = null;
                _HWR_SpeechToText =
                            (HttpWebRequest)HttpWebRequest.Create(
                                "https://www.google.com/speech-api/v2/recognize?output=json&lang=en-us&key=YOUR_API_KEY_HERE");
                _HWR_SpeechToText.Credentials = CredentialCache.DefaultCredentials;
                _HWR_SpeechToText.Method = "POST";
                _HWR_SpeechToText.ContentType = "audio/x-flac; rate=44100";
                _HWR_SpeechToText.ContentLength = BA_AudioFile.Length;
                Stream stream = _HWR_SpeechToText.GetRequestStream();
                stream.Write(BA_AudioFile, 0, BA_AudioFile.Length);
                stream.Close();

                HttpWebResponse HWR_Response = (HttpWebResponse)_HWR_SpeechToText.GetResponse();
                if (HWR_Response.StatusCode == HttpStatusCode.OK)
                {
                    StreamReader SR_Response = new StreamReader(HWR_Response.GetResponseStream());
                    Console.WriteLine(SR_Response.ReadToEnd());
                }

            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }

            Console.ReadLine();
        }
    }
}

Also I tried to use Bing Speech API, but seems it's only for use in XAML apps here msdn.microsoft.com/en-us/library/dn434606.aspx and msdn.microsoft.com/en-us/library/dn467592.aspx

then I found this list of tools, but seems like is nothing for free http://www.dmoz.org/Computers/Speech_Technology/Toolkits/