Web Audio

var context=  new (window.AudioContext || window.webkitAudioContext)();
var oscillator = context.createOscillator();
oscillator.frequency.value = 5000;
oscillator.start();
oscillator.connect(context.destination);

This starts with a tone with a frequency of 5000 which most people with hearing should be able to notice it.

If you create a tone with a frequency greater than 15000 only those under 40 will be able to hear it and a frequency above 17500 can be heard by only by those 18 and younger.

oscillator.frequency.value = 15000;
oscillator.frequency.value = 17500;

This festive season why not turn your speakers up high and use this method (starting at 17500 and then reducing by 1000 at a time) to figure out who is the youngest in your office.

If you want the sound to stop simple run this:

oscillator.stop();

The following demo shows how you could record and visualise audio coming from a Microphone:

Test Drive Recoder

The following demo shows how you can build a simple tuner:

A simple tuner example with code talk through

Published by thebeebs

Martin has been a web developer since 2000 and now work for Microsoft as a technical evangelist.