Audio reactive visualisation

HTML

<!DOCTYPE html>
<html>
    <head>
        <meta name="description" content="HTML5 Audio Spectrum Visualizer">
        <title>HTML5 Audio Spectrum Visualizer - Alexandre Juca</title>
        <link href='http://fonts.googleapis.com/css?family=Oswald:700' rel='stylesheet' type='text/css'>
        <link type="text/css" rel="stylesheet" href="style/style.css">
    </head>
    <body>
        <div id="wrapper">
            <div id="fileWrapper" class="file_wrapper">
            <input type="file" id="uploadedFile"></input>
            </div>
            <div id="visualizer_wrapper">

                 <canvas id='mono-L' width="600" height="650"></canvas>
                <canvas id='mono-R' width="600" height="300"></canvas>
            </div>

        </div>
        
        <script type="text/javascript" src="js/visualizer.js"></script>
    </body>
</html>