Fletcher-Munson Hearing Test

If you play two sine waves with the same amplitude but different frequencies, one may sound louder than the other. This is because our ear does not hear very low or very high frequencies as well as it hears frequencies that are in the middle.

In this applet, we play a reference tone that is at a frequency around the middle of our range of hearing. Then we play a test tone at increasing frequencies. The test tone will always be at full amplitude, but it may not sound very loud depending on its frequency.

To do:

Start by hearing the low tone. (You may not be able to hear the lowest note if you are listening to the speakers on a laptop computer. Try using headphones or external speakers.)
Adjust the fader until you hear a higher tone at the same apparent loudness as the low tone. There is no "correct" level. Just adjust the level until the tones "seem" to have the same loudness to your ear.
When you get the two tones to have the same amplitude, hit the Next Frequency button. The amplitude and frequency of the reference tone will be plotted on the chart.
Continue adjusting the level and hitting the Next Frequency button until you complete the chart.
Notice the shape of the curve.

Note that this is not only a test of your ears, but also a test of your stereo sound system and the acoustics of the room you are in. All of these can affect how loud you hear a specific frequency.