Here's why:
* The 'wh' sound: The initial 'wh' sound in "whisper" suggests a soft, breathy quality, similar to how a whisper is produced.
* The 's' sound: The 's' sound in "whisper" is also associated with softness and quietness.
* The 'per' sound: The 'per' sound, while not directly mimicking a sound, adds to the feeling of a quiet, hushed utterance.
Therefore, even though "whisper" doesn't perfectly replicate the actual sound of whispering, it evokes the feeling and impression of a whisper through its sound symbolism. This is a characteristic of onomatopoeia, where words imitate or evoke the sounds they represent.