A structure having a hole, including a substrate, a first layer including an alumina hole, and a second layer disposed between the substrate and the fist layer, wherein the second layer contains silicon, and has a smaller hole than the alumina hole. The catheter structure includes an elongated tube structure having distal and proximal ends. For each of the periodic intervals, at least one impairment factor is measured, an estimated effect of each of the impairment factors is determined using at least one value, and an estimated subjective quality of the signal is determined using the estimated effect of each of the impairment factors. The probe is moved to make an arrangement of the contact styli matching the pattern of the measurement points.