The point is that objectivity is established by multiple observations, especially by unbiased observers, and by controlled experiments.
Scientific instruments extend our senses through telescopes and microscopes, and x-rays, and magnetic imaging, etc., making the invisible measurable. But it is still ultimately us, interpreting what we see.
Multiple observations by unbiased observers aren't nearly enough to establish control of elements in experiment. The aspects of the object being specified for test must be be materially established. By material establishment the object must be described in more fundamental reductionist terms already established as part of the body of science such as mass, extent, dimension, temperature, velocity, elemental configuration etc. Its what I've been calling materiality.
That you are providing a well defined acoustics signals to the ear isn't enough to raise the results of observations to psychometrics. The specifications must at a minimum also include randomization of conditions, temporal and procedural order of experimental process bringing the signals to the ears and responses from the fingers of the observers. As well as accounting for time and extent of test sessions along with controls for specific verified repeatable operations. then there is the review and commentary prior to publication then there is editorial acceptance and publication to specific communities.
Each sense tells us something different. Is this "really" an apple? It looks like an apple, but when I pick it up it is much lighter, and if I thump it with my knuckle it feels hard, but it sounds hollow. Hmm. It is an artificial apple, put in this bowl of artificial fruit for decoration.
Since each sense uses differing aspects associated with reality their relationships to one another need be refined to specific material dimensional and material concomitants. Even then experiments need be conducted verifying the onto nature of such relationships.
Right. We presume the "existence" of a wall when we bump into it. Bumping into the wall is a "measure" of its solidity, its hardness, and its realness.
Our abilities to verify it's attributes are still indirect and do not qualify as evidence realness by kind.
You have miles and miles go before you begin to understand materiality and experiment. And you certainly don't understand what is meant by scientific experiment. What you talk to is causal study or investigation. Nothing material nor scientific can be properly reported from such.
I think you'll find
https://plato.stanford.edu/entries/operationalism/ and Wiki's article addressing Percy Bridgman's
Operationalism enlightening. I'm a an Acoustical psychophysicist by early doctoral training and practice who was confused by SS Stevens and BF Skinner's interpretations.
So I went to the source which is much more adequate and useful. And as he concludes "The scientific method, as far as it is a method, is nothing more than doing one’s damnedest with one’s mind, no holds barred.” My added thought is "The mind always suspect need be as far removed from evidence as methodologically possible." ... and by all accounts he plotted a pretty good path because establishment of materiality is proof positive that mind is a contaminant.