Speech To Text Method

        private static async Task<Stream> Upload(string modelString, byte[] audioFile)
        {
            HttpContent modelContent = new StringContent(modelString);
            HttpContent partContent = new StringContent("audio/wav");
            HttpContent continuousContent = new StringContent("true");
            HttpContent audioContent = new ByteArrayContent(audioFile);
            string actionUrl = "https://stream.watsonplatform.net/speech-to-text/api/v1/recognize";

            using (var client = new HttpClient())
            {
                var byteArray = new UTF8Encoding().GetBytes("<username>:<password>");
                client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", Convert.ToBase64String(byteArray));

                using (var formData = new MultipartFormDataContent())
                {
                    formData.Add(modelContent, "model");
                    formData.Add(partContent, "audio/wav");
                    formData.Add(continuousContent, "continuous");
                    formData.Add(audioContent, "file1", "file1.wav");

                    var response = await client.PostAsync(actionUrl, formData);
                    if (!response.IsSuccessStatusCode)
                    {
                        return null;
                    }
                    return await response.Content.ReadAsStreamAsync();
                }
            }
        }