how to preload audio files for in-time use?

I am using — public AudioClip soundA; … audio.PlayOneShot(soundA); in my scripts.
But it sounds quite late. Makes the app in poor quality.
I think there is a way to preload audio clips.

Can anyone give me some advice on this?
Thanks in advance for any help.

Never mind. I fixed it. It seems my audio files have some problems.