In acoustics and audio, a transient is a high amplitude, short-duration sound at the beginning of a waveform that occurs in phenomena such as musical sounds, noises or speech.
[1][2] Transients do not necessarily directly depend on the frequency of the tone they initiate.
It contains a high degree of non-periodic components and a higher magnitude of high frequencies than the harmonic content of that sound.
[3] Transients are more difficult to encode with many audio compression algorithms, causing pre-echo.
[4]