Has anyone used windows bing speech to text in Unity for hololens?

Hi, I am trying to build a voice enabled interactive chat application on hololens. For speech to text conversion i am using Unity’s built-in class DictationRecognizer for now. But its perfomance is very poor.
When i try to use Bing REST API, i am getting error.

try
{
var token = auth.GetAccessToken();
Console.WriteLine("Token: {0}
", token);
Console.WriteLine("Request Uri: " + requestUri + Environment.NewLine);

        HttpWebRequest request = null;
        request = (HttpWebRequest)HttpWebRequest.Create(requestUri);
        request.SendChunked = true;
        request.Accept = @"application/json;text/xml";
        request.Method = "POST";
        request.ProtocolVersion = HttpVersion.Version11;
        //request.Host = host;
        request.ContentType = contentType;
        request.Headers["Authorization"] = "Bearer " + token;
        //request.UseDefaultCredentials = true;
        request.Proxy.Credentials = System.Net.CredentialCache.DefaultCredentials;

        using (fs = new FileStream(audioFile, FileMode.Open, FileAccess.Read))
        {

            /*
             * Open a request stream and write 1024 byte chunks in the stream one at a time.
             */
            byte[] buffer = null;
            int bytesRead = 0;
            using (Stream requestStream = request.GetRequestStream())
            {
                /*
                 * Read 1024 raw bytes from the input audio file.
                 */
                buffer = new Byte[checked((uint)Math.Min(1024, (int)fs.Length))];
                while ((bytesRead = fs.Read(buffer, 0, buffer.Length)) != 0)
                {
                    requestStream.Write(buffer, 0, bytesRead);
                }

                // Flush
                requestStream.Flush();
            }

            /*
             * Get the response from the service.
             */
            Console.WriteLine("Response:");
            using (WebResponse response = request.GetResponse())
            {
                Console.WriteLine(((HttpWebResponse)response).StatusCode);

                using (StreamReader sr = new StreamReader(response.GetResponseStream()))
                {
                    responseString = sr.ReadToEnd();
                }

                Console.WriteLine(responseString);
                Console.ReadLine();

                File.Delete(filePath);
            }
        }
    }
    catch (Exception ex)

    {
        Console.WriteLine(ex.ToString());
        Console.WriteLine(ex.Message);
        Console.ReadLine();
        File.Delete(filePath);
    }

i dont know what is your target
but for speech to text in hololens its better to use IBM watson it can be used for
microsoft hololens also.