Take it that you can hear an infinite bandwidth, infinite dynamic range and an infinite temporal resolution. You can hear light moving across the room. You can hear the Earth turning on its axis. You can hear the reverberations of the concert you attended last week in perfect fidelity (and greater spaciousness). Etc. Etc. At some point introducing limits becomes relevant. So how are these things to be determined, what is really happening? Dynamic range is disturbances in barometric pressure, bandwidth is sensitivity to those disturbances by frequency and reverberation by the decay of those disturbances over time. Perhaps all of this stuff feels nebulous and the language too jargonish, but the question of limits is important. You can chop out a whole load of things pretty quickly, and then the details start mattering.
Chomsky said once that everyone at MIT knows the classical laws and the names behind them (Newton...) but no one actually reads them. They just memorize the formulas and learn the fundamental relationships and move on. So why not read the ancient texts on sound? Reading those books is like being witness to the evolution of knowledge, and will actually clarify the why of things, like why it became necessary to delve develop specialized apparatus for experiments, which eventually led to audio analyzers.
The early Greeks had no concept of frequency, intensity or wavelength, a confusion which persisted until the Renaissance, with the most authoritative texts having it that, the harder the impact to an object, the higher sound produced (instead of being louder, more intense), or the faster the flautist blows into the mouth of his flute, the higher the note (again, louder or more intense, but also appreciating the effects of under/overblowing techniques). Read the very astute observation by the Arab thinker Al-Jurjani around the end of the 14th century that they can define no mathematical relationship for pitch between strings of various lengths despite hearing the difference because they have
no practical means for measuring tension or accurately determining thickness. That's equivalent to saying: before we can move further with this science we have to figure out these very specific problems, problems which revolve around accurate measurement.
Back to the the topic at hand.
@PeterZui Hold yourself to your claims: if you really believe that electrical measurements are not that important, then study what, exactly, it's possible to measure and with what level of accuracy. Be precise about your criticisms. Soundstage and perception, as topics, are too broad. You could ask generally:
- How accurately a person can localize a sound on the horizontal plane, on the vertical plane, or in terms of depth: Are people equally accurate at vertical localization as horizontal? Is vertical stereo possible? Are people pinpoint accurate or are there tolerances within a range of degrees? Beyond a certain distance, does a person's accuracy begin to diminish?
- If perception of timbre is related to transient response: What happens when a signal is compressed broadband?
- If perception of muddiness, clarity or presence can be correlated to frequency response: Does an upwards spectral tilt toward the high frequencies just mean that everything sounds brighter, or does something happen to the overall perception of quality as well?
- What's louder: a moderate-level single tone at one frequency, or wide-band but low-level white noise? Is it possible to set levels so that they seem equally loud? If so, then at what levels? Does the frequency of the tone matter? Is it possible to set the single tone at one level and then adjust the bandwidth of noise until they are equally loud without changing the noise's level? Does the tone always have to be louder than the noise to be audible, or not?
- What's the smallest controllable difference you can identify consistently and easily? Are you equally good at perceiving pitch, duration, level, and sequence (as in a musical sequence, aka the strength of your auditory memory)?
Then compare your answers to what's been measured. That list of questions is nothing outlandish, even familiar. I think it's a good representation of your concerns and, importantly, every aspect can be compared and measured using very simple instrumentation (a protractor, a ruler, a computer to set levels and EQ). If you cover this stuff then maybe the APx555 graphs won't be so abstract.