Numerous other studies have contradicted the portion of the results relating to the subjective reaction to high-frequency audio, finding that people who have "good ears"[8] listening to Super Audio CDs and high resolution DVD-Audio recordings[9] on high fidelity systems capable of reproducing sounds up to 30 kHz[10] cannot tell the difference between high resolution audio and the normal CD sampling rate of 44.1 kHz.[8][11][5][13]