change bit duration via UI

index.html

@@ -9,6 +9,7 @@
     <h1>Data Over Audio</h1>
     <div class="panels">
       <div>
+        Bit Duration: <input id="bit-duration-text" type="number" min="0" max="1000" value="180">ms<br>
         <input type="text" id="text-to-send">
         <button id="send-button">Send</button>
         <h2>Sent</h2>