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Voice-Driven Native Mobile Apps with IBM Watson & IBM MobileFirst

Create an application to transcribe speech to text using IBM Watson's service, along with help from Bluemix and MobileFirst.

· Mobile Zone

Using your voice to drive interactions within your app is a powerful concept. It is the primary interaction driving Apple’s Siri, Microsoft’s Cortana, and Google’s Voice Actions. By analyzing spoken words, voice commands allow you to complete possibly complex actions with minimal interaction with the device. Or, they enable entirely different forms of interaction, for example, interacting with a remote system through the telephone.

Voice driven interactions are essentially a two part process:

  • Transcribe audible signal to text transcript
  • Perform a system action by parsing text transcript

If you think that voice-driven apps are too complicated, or out of your reach, then I have great news for you: They are not! Last week, IBM elevated several IBM Watson voice services from Beta to General Availability – that means you can use them reliably in your own systems too!

Let’s examine the two parts of the system, and see what solutions IBM has available right now for you to take advantage of…

Transcribe audible signal to text transcript

Part one of this equation is converting the audible signal into text that can be parsed and acted upon. The IBM Speech to Text service fits this bill perfectly, and can be called from any app platform that supports REST services… which means just about anything. It could be from the browser, it could be from the desktop, and it could be from a native mobile app. The Watson STT service is very easy to use, you simply post a request to the REST API containing an audio file, and the service will return to you a text transcript based upon what it is able to analyze from the audio file. With this API you don’t have to worry about any of the transcription actions on your own – no concern for accents, etc… Let Watson do the heavy lifting for you.

Perform a system action by parsing text transcript

This one is perhaps not quite as simple because it is entirely subjective, and depends upon what you/your app is trying to do. You can parse the text transcript on your own, searching for actionable keywords, or you can leverage something like the IBM Watson Q&A service, which enables natural language search queries to Watson data corpora.

Riding on the heels of the Watson language services promotion, I put together a sample application that enables a voice-driven app experience on the iPhone, powered by both the Speech To Text and Watson Question & Answer services, and have made the mobile app and Node.js middleware source code available on github.

Watson Speech QA for iOS

This native iOS app, which I’m calling “Watson Speech QA for iOS” allows you to ask Watson questions in natural, spoken language, and receive textual responses based on the Watson QA Healthcare data set.

Check out the video below to see it in action:


Bluemix Services Used

This app uses three services available through IBM Bluemix:

  1. Speech to Text – Convert spoken audio into text
  2. Question & Answer – Natural language search
  3. Advanced Mobile Access – Capture analytics and logs from mobile apps running on devices

IBM Watson Speech QA for iOS App Architecture

The app communicates to the Speech to Text and Question & Answer services through the Node.js middelware tier, and connects directly to the Advanced Mobile Access service to provide operational analytics (usage, devices, network utilization) and remote log collection from the client app on the mobile devices.

For the Speech To Text service, the app records audio from the local device, and sends a WAV file to the Node.js in a HTTP post request. The Node.js tier then delegates to the Speech To Text service to provide transcription capabilities. The Node.js tier then formats the respons JSON object and returns the query to the mobile app.

For the QA service, the app makes an HTTP GET request (containing the query string) to the Node.js server, which delegates to the Watson QA natural language processing service to return search results. The Node.js tier then formats the respons JSON object and returns the query to the mobile app.

The general flow between these systems is shown in the graphic below:

Image title

IBM Watson Speech QA for iOS – Logic Flow

Code Explained

Mobile app and Node.js middleware source code and setup instructions are available at: https://github.com/triceam/IBM-Watson-Speech-QA-iOS

The code for this example is really in 2 main areas: The client side integration in the mobile app (Objective-C, but could also be done in Swift), and the application server/middleware implemented in Node.js.

Node.js Middleware

The server side JavaScript code uses the Watson Node.js Wrapper, which enables you to easily instantiate Watson services in just a few short lines of code

var watson = require('watson-developer-cloud');
var question_and_answer_healthcare = watson.question_and_answer(QA_CREDENTIALS);
var speechToText = watson.speech_to_text(STT_CREDENTIALS);

The credentials come from your Bluemix environment configuration, then you just create instances of whichever services that you want to consume.

I implemented two methods in the Node.js application tier. The first accepts the audio input from the mobile client as an attachment to a HTTP POST request and returns a transcript from the Speech To Text service:

// Handle the form POST containing an audio file and return transcript (from mobile)
app.post('/transcribe', function(req, res){

  //grab the audio WAV file attachment and prepare to send to Watson
  var file = req.files.audio;
  var readStream = fs.createReadStream(file.path);
  console.log("opened stream for " + file.path);

  var params = {
    content_type:'audio/l16; rate=16000; channels=1',

  //send the audio WAV file to the watson.recognize service
  speechToText.recognize(params, function(err, response) {

    if (err) {
      return res.status(err.code || 500).json(err);
    } else {
      //parse the results and return them to the client
      var result = {};
      if (response.results.length > 0) {
        var finalResults = response.results.filter( isFinalResult );
        if ( finalResults.length > 0 ) {
          result = finalResults[0].alternatives[0];
      return res.send( result );

Once you have the text transcript on the client, you could do whatever you want with it. You could parse it to invoke local actions, or delegate to a natural language query service

The second method does exactly this: it accepts a URL query parameter from a HTTP GET request and uses that parameter in a Watson QA natural language search:

//handle QA query and return json result (for mobile)
app.get('/ask', function(req, res){

  //get a copy of the search query text from the req.query object
  var query = req.query.query;

  if ( query != undefined ) {
    //perform a search using the QA "ask" method
    question_and_answer_healthcare.ask({ text: query}, function (err, response) {
      if (err){
        return res.status(err.code || 500).json(response);
      } else {
        //format the results and return them to the mobile client
        if (response.length > 0) {
          var answers = [];

          for (var x=0; x<response[0].question.evidencelist.length; x++) {
            var item = {};
            item.text = response[0].question.evidencelist[x].text;
            item.value = response[0].question.evidencelist[x].value;

          var result = {
          return res.send( result );
        return res.send({});
  else {
    return res.status(500).send('Bad Query');

Note: I am using the free/open Watson Healthcare data set. However the Watson QA service can handle other data sets – these require an engagement with IBM to train the Watson service to understand the desired data sets.

Native iOS – Objective C

On the mobile side we’re working with a native iOS application. My code is written in Objective C, however you could also implement this using Swift. I won’t go into complete line-by-line code here for the sake of brevity, but you can access the client side code in the ViewController.m file. In particular, this is within the postToServer and requestQA methods.

You can see the flow of the application within the image below:

Image title

App Flow: User speaks, transcript displayed, results displayed

The native mobile app first captures audio input from device’s microphone. This is then sent to the Node.js server’s /transcribe method as an attachment to a HTTP POST request (postToServer method on line 191). On the server side this delegates to the Speech To Test service as described above. Once the result is received on the client, the transcribed text is displayed in the UI and then a request is made to the QA service.

In the requestQA method, the mobile app makes a HTTP GET request to the Node.js app’s /ask method (as shown on line 257). The Node.js app delegates to the Watson QA service as shown above. Once the results are returned to the client they are displayed within a standard UITableView in the native app.

MobileFirst – Advanced Mobile Access

A few other things you may notice if you decide to peruse the native Objective-C code:

  1. Within AppDelegate.m you will see calls to IMFClient, IMFAnalytics, and OCLogger classes. These enable operational analytics and log collection within the Advanced MobileAccess service.
  2. All network requests inside of ViewController.m use the IMFResourceRequest class. Using the IMFResourceRequest class enables the collection of analytics for every request made within the application (through this class).

Together these allow for the collection of device logs, automatic crash reporting, and operational analytics that provide one of the strengths of the Advanced Mobile Access service, which is one of the mobile offerings on IBM Bluemix.

Source Code

Mobile app and Node.js middleware source code and setup instructions for this app are available at:

  • https://github.com/triceam/IBM-Watson-Speech-QA-iOS
  • Just create an account on IBM Bluemix, and you have everything that you need to get started creating your own voice-driven apps.

    mobile ,iot ,ibm watson ,ibm mobilefirst ,native apps

    Published at DZone with permission of Andrew Trice, DZone MVB. See the original article here.

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