Hi, I was thinking if we can make custom police scanner audio. There are tons and tons of audio files in Police Scanner but some of them are no use to me. If anybody knows how to make custom police scanner audio can tell please tell me!! Thank you! 

You can record them yourself, or use a text-to-speech application. But they won't sound like the GTA V dispatcher voice.

You can also splice parts of the GTA V scanner files and combine them to make new clips with Audacity.

How do I create Police scanner files 

I did make a WAV files

You just place the wave-file in the folder with the soundfiles inside your plugins-sub-domain like myPlugin.
Lets say you have the sound-file backMeUp.wav
Then where you want this sound to be played you write:

Functions.PlayScannerAudioUsingPosition("GTAV\lspdfr\audio\scanner/myPlugin/sounds/backMeUp.wav");

 

If you on the other hand want to replace sounds from lspdfr with your own, then you substitute a file from ..GTA5\GTAV\GTAV\lspdfr\audio\scanner with your own file.