Target size is tough with the Tiger, but larger targets, like cans, will still give a strong signal when you lift your coil about 6" off the bottom, whereas a coin will fade quicker, or sound smaller. Some times its difficult to tell big targets.
The noise you experience might be the falsing that occurs when your cable to control box connector goes in and out of water. Because of the removable connector some machines false when the connector hits the water, and then falses again when connector leaves the water. If you are hunting at a depth where wave action is alternating this action, you will hear falsing. Try experimenting next time out to see if this scenario matches what you are hearing. The first runs of Tigers have this problem and I dont think it can be corrected at the factory. I have one of the first ever built and mine reacts that way, so I simply crouch or "tippy toe" to get past that water level. On later production models they made a modification and newer machines should not have this problem. If your machine is less than 2 years old and falses from the water line, you should send it back in with a description of the problem, and they will probably be able to fix it. If you have an older Tiger, you may have learn to live with it.
