As we age, our ability to hear high frequencies gradually decreases. This process typically begins in our 20s and progresses throughout life. By our 40s or 50s, many people have significantly reduced sensitivity above 12-14 kHz. Interestingly, as we lose high-frequency sensitivity, our ears can become relatively more sensitive to mid-range frequencies (1-3 kHz), sometimes leading to a perception of increased harshness in this range.