To cut audio from a big audio file we can use ffmpeg.
In following example I am trying to cut audio from input.mp3 file. Here I am cutting audio from 30th second to 50 seconds.
ffmpeg -ss 00:00:30.0 -t 00:00:20.0 -i input.mp3 -acodec copy -vcodec copy -async 1 output.mp3
-ss to starting time
-t to number seconds/minutes/hours after starting time.
-acodec copy will make output.mp3 with same properties (bitrate) as input.mp3