Question: As described in several books, the process of recognition of isolated words consists of the following:

1. For a given set of signals(templates), determine feature vector for
each template – matrix M×N, where M is number of
features(MFCC,ZCR,…) and N is number of frames.
2. Train the templates with some algorithm, such as ANN, HMM, GMM, SVM.
3. Recognize test signal by trained model.

Because speech signals have different duration, their lengths are aligned by Dynamic Time Warping (DTW) technique, so that N is same for all templates. It can be done during training.

My question is: How to change length of test signal? I can not use DTW on it, since I do not know to which class it belongs. Should I use "time stretching" algorithms, preserving pitch and if I should, how this will affect recognition accuracy?

Answer: 
I think you can't see the back button because you don't push page to the stack.

For this you need to add an ons-navigator directive and use its "pushPage()" methode.

Check the documentation, specialy the live exemple: <http://onsen.io/reference/ons-back-button.html>
If you need ons-back-button behavior in a page load from ons-sliding-menu add the ons-navigator directive in index.html and use in menu.html the pushPage() method and menu.closeMenu()

index.html:

```
<body>
  <ons-navigator animation="slide" var="myVar">  
    <ons-page>
      <ons-sliding-menu menu-page="menu.html" main-page="home.html" side="left" var="menu" type="reveal" max-slide-distance="260px" swipable="true" swipe-target-width="50">
      </ons-sliding-menu>
    </ons-page>
  </ons-navigator>
</body>  

```

menu.html:

```
<ons-list class="menu-list">
  <ons-list-item class="menu-item" ng-click="myVar.pushPage('about.html'); menu.closeMenu()">
    <ons-icon icon="fa-info-circle" fixed-width="true"></ons-icon> About
   </ons-list-item>
</ons-list>

```

home.html:

```
<ons-page>
    <ons-toolbar modifier="opacity">
      <div class="left">
        <ons-toolbar-button ng-click="menu.toggle()">
           <ons-icon icon="ion-navicon-round" fixed-width="false"></ons-icon>
        </ons-toolbar-button>
      </div>
      <div class="center">Title 1</div>
    </ons-toolbar>
    <div class="app-page">
      <ons-list>
        <ons-list-item modifier="chevron" class="list-item-container" ng-click="myVar.pushPage('mypage.html');">
          <ons-row>...

```