Use new earcons in ChromeVox Next.

chrome/browser/resources/chromeos/chromevox/cvox2/background/earcon_engine.js

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @fileoverview This is the low-level class that generates ChromeVox's
  * earcons. It's designed to be self-contained and not depend on the
  * rest of the code.
  */
 
 goog.provide('EarconEngine');
 
 /**
  * EarconEngine generates ChromeVox's earcons using the web audio API.
  * @constructor
  */
 EarconEngine = function() {
   // Public control parameters. All of these are meant to be adjustable.
 
   /** @type {number} The master volume, as an amplification factor. */
-  this.masterVolume = 0.2;
+  this.masterVolume = 1.0;
 
   /** @type {number} The base relative pitch adjustment, in half-steps. */
   this.masterPitch = -4;
 
   /** @type {number} The click volume, as an amplification factor. */
   this.clickVolume = 0.4;
 
   /**
    * @type {number} The volume of the static sound, as an
    * amplification factor.
@@ skipping 670 matching lines @@
   }
 
   for (var i = 0; i < this.progressSources_.length; i++) {
     this.progressSources_[i][1].stop();
   }
   this.progressSources_ = [];
 
   window.clearInterval(this.progressIntervalID_);
   this.progressIntervalID_ = null;
 };