High frequency, in the headphone and audio field, typically refers to the sound band ranging from 2000 Hz (2 kHz) to 20000 Hz (20 kHz). It corresponds to overtones, sibilance, cymbals, triangles, and high-position harmonics of string instruments in music, and is the key region that determines the "airiness" and "brightness" of sound. Simply put, high frequency determines the clarity, detail retrieval, and spatial sense of sound; if it is lacking, the overall listening experience will feel dull and muffled, as if listening through a layer of cloth.
In terms of listening experience, the tuning of high frequency directly influences the stylistic direction of a headphone. Excessive and sharp high frequencies can produce a "harsh" or "overly sibilant" sound, causing fatigue during prolonged listening; while smooth, naturally extended high frequencies deliver a transparent, brilliant, and layered sound, enhancing instrument separation and soundstage performance. When purchasing, high-frequency performance is an important indicator of a headphone's quality, especially suitable for fans of classical music, strings, or vocals, but attention should be paid to whether its transition with the mid and low frequencies is seamless, avoiding a "disconnected" or "dry and cold" listening experience.
Practical advice: during auditions, choose high-quality recordings with plenty of cymbals or triangles, and appropriately lower the volume. If you can still clearly capture delicate overtones without harshness at low volume, then the headphone's high-frequency handling is quite excellent.