Some interesting "Equal Loudness Curve" experimements at hearing threshold levels, can be performed online:
1. Calibrate http://mynoise.net/calibration.php
2. Play back any noise (such as the rain noise here http://mynoise.net/NoiseMachines/rainNoiseGenerator.php)
3. Load your personal calibration curve, by clicking the "Personal Curve" setting (and see the sliders move to your hearing thresholds)
Although I agree one shouldn't use the Equal Loudness Curve to equalize your audio equipment - it is still a nice trick to compensate for your ageing hearing loss...