As we age the higher frequency hearing loss is what most people experience. No amount of training can compensate for what no longer exists. Train all you want but if you ain't got it you can't do it.Training is more important than testing.
It's my theory... (warning, hear comes another fairy tale!) Most systems I listen to at the audio shows are shifted to the bright side. Why? The buying customer is an older male and has some level of HF hearing loss. Brighter speakers sound better to them.
I had the pleasure of driving high end cars as a quality control inspection. These vehicles come with excellent stereo systems. Here's a fact... almost every car I tested the customer had the treble pushed to the higher limit. The bass not so much but the treble was always at abnormally bright levels. The customer is an older male probably with HF hearing loss. Even the younger ones prefer a 'hyper realistic' treble. It's a definite trend. This didn't need measuring to hear it.