I noticed as a young kid that fish seem to respond or react to the sounds things make when they hit the water just as much as they seem to react to their appearance. Clear water and many, many repetitions convinced me that the sound of the "plop" made almost as much of a difference in fish's reactions as the item's looks. Dad used to find himself out of beer, and one of his favorite Sunday afternoon activities was to dispose of a good cold one at a leisurely pace. Only problem was the beer stores were closed on Sunday, so he'd go to a local bootlegger he knew that ran from a big mill pond, and while he took care of his business there, I'd catch and throw grasshoppers, crickets, or anything I could find in the water, and it being clear and my being almost directly above them in the millhouse, I got a good view of them at rest and how they responded to the many various offerings I'd catch. The flightless pea green (chartreuse or green chartreuse) grasshoppers were always the hands down winner for fastest reaction and least degree of caution shown by the fish. It seemed they didn't have to be facing the "plop" to be able to tell what was hitting the water. That's when I began to realize that the sound made such a difference. I then observed that those chartreuse hoppers seemed to be built a little denser than the crickets, and most other colors of grasshoppers. I've reverified this many times through the years. That changes the character and degree of the sound light wt. insects make when hitting the water, and fish seem to respond to those variations in sound. I also know that water is a MUCH better conductor of sound, and that it travels 4 times as fast through water than it does in air. This, I reason, should be a help to fish's hearing, and what allows them to sense sounds so well through their lateral lines, or maybe other mediums that help them sense sounds/pressure waves of whatever kind. That makes me think that the subtleties of the sounds a lure or fly make on entry into the water is more of a factor than we often give it credit for being.
I've tried often through the years to recreate the density, weight, etc. of various flies and lures to test my theory, but have not been able to have consistent success doing it, probably because I'm usually more at ease when I'm tying and don't really "bear down" in my efforts to recreate some "plops" that I sort'a half-way am trying to duplicate, but what successes I HAVE had have been kind'a interesting. Just adding some epoxy glue to foam spiders or other flies can have an impact, I think, though it's not all that great, usually. However, we've all probably had experience with a single particular fly we've tied producing better than others that look essentially the same. I can't help but wonder if the "plop factor" isn't at least sometimes a factor in this?
Have any of you observed anything like what I have, and what have you done or been able to do with the observation? I've found simple eyes made from plastic bead headed straight pins can make a difference, but whether it's the look or the slightly altered "plop" that makes the difference, I can't tack down, so have to resort to surmising what the difference really is. Anybody got some comments on all this? Observations? Ideas to input?