One of my favorites for a solo trumpet was to back the volume down and add a little brilliance. It wasn't any louder, just seemed more present and was easy to focus on.
Just thought of something else, ever seen the Fletcher Munson curve.
Maybe we could talk about the masking effect.
How about the new problems. Crosstalk and print thru. lol
Did you know with a non headphone situation tones below 250 hz become omnidirectional?
When using headphone sometimes rolling the highs off around 6k at 12db per octave helps avoiding ear fatigue on some instruments.
Did you know you can pan images by delaying one side or the other.
Ducking filters are used for many things. Do you know why?
What areas on the frequency response are the most sensitive to the human ear?
Why use rumble filters?
Why do mics mounted on manikins sound so natural?
Is it good to have a variety of microphones around?
What is the polar response all about?
Did you know line array speakers drop 3 db instead of 6 when you double your distance from the speakers?
Why are there different tunings other than the equal temperament? Where can they be used?
What is the ideal listening volume?