Sound from old film is unlike any other audio media, and it exhibits different defects than what other audio will exhibit. Those thin strips of magnetic audio, or that potentially faded optical track can only hold so much information. There is, however, room to make improvements.
We use proprietary methods to get higher gain - meaning we're able to increase the amount of signal we can get on the initial capture. The more signal, the more room we have to make improvements.
We do that by using custom-made audio filters based on the sound characteristics of 8mm and 16mm films. With these filters, we're able to reduce the unwanted high-frequency noise (hiss) and low-frequency noise (rumble).
When you eliminate the hiss and rumble, you're able to improve overall volume without amplifying any of the junk noise on the high and low end. All of this is done to improve the intelligibility of the track.