When we got our hands on these sirens, they had to be trimmed down to make a clean loop. The source video used to trim to this loop sounded like there was a very slight pause in the first siren
As for the quiet one, we tried to address this as well by simply raising the audio, but raising it higher than it is set to distorted the audio severely and made it insufferable to listen to, we can't do much about it without a new, clean audio file which is louder to work with.