High quality, super-cardiod and hyper-cardiod mics have a very short range. And, as such, they usually cannot pick up any sounds more than a few inches from the mic head, and those sounds must be fired directly into the face of the mid. Sound such as echoes from within the room would not be picked up, mainly because they would be primarily coming from the sides of the mic. The face of the mic is blocked by the singer's head.
The test is very simple. Place a high quality mic on a mic stand, point the mic directly at your mouth, sing directly into the mic's face, then using the same vocal volume, sing into the side of the mic--what a diffence. The fall-off is astronomical with a top-quality mic. If you're using an inexpensive mic, the fall-off is not nearly as significant.
Good luck on whatever decission you make,
Gary
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Travlin' Easy