Is it possible to measure timbral accuracy?
While frequency response measurements can tell us a lot, they don't fully convey how accurately an audio system reproduces the unique textures and colors of different voices and instruments—the timbral quality that makes a piano sound distinct from a violin, for example.
And to further increase the difficulty in this challenge, what happens when you modify the parameters you can measure? Does a piano still sound like a piano if you boost the treble control?
Imagine a group of people listening to a recording of a solo male singer. How might we measure the timbral accuracy of that recording? At what point do we find it hard to identify the quality of the man's voice?
You and I, listening to our high-end systems, have all experienced improvements and degradations in timbral accuracy. Right? The piano's harmonic overtones are more richly produced on this amplifier than that amplifier. Is there a measurable difference between amplifiers? Of course there is.
Is there a measurement that might tell us what to expect in timbral accuracy? Maybe, but to my knowledge, no one has yet definitively stated that a change in frequency, phase, or amplitude has any measurable impact on our ability to recognize timbral accuracy in instruments or voices.
And this is the problem. We think something is true—heck, we know something is true—but proving it?
Take a philosophical argument as an example. Does the outside world exist? It is challenging to prove the objective existence of an external world that exists independently of your perception. Philosophers have debated whether our sensory experiences accurately represent reality or if they are mere perceptions constructed by our minds. Go in one direction and it's pretty easy: a needle poke in the finger will draw blood. Go in the other direction, imagining the results of a physical action, and things get a lot more difficult.
We cannot really measure timbral accuracy by any reliable means other than our ears.
Tomorrow, the ultimate test.