The restoration of audio materials, unlike other applications, such as photography or printed matter, should be understood and is performed entirely at the level of content, that is to say of the sound itself, and not of the physical object that contains it.
The Swiss National Sound Archives has two restoration studios equipped with all the devices necessary for the various types of restoration (see below). However, it does not spontaneously make any changes that alter the original timbre of an audio document.
Two qualified technicians perform every single restoration operation in compliance with the "Principles of Copying and Restoration" published on this website. To optimize the operations, the Swiss National Sound Archives uses, at least in part, automated systems.
The restoration operations can be classified into two main categories: technical and artistic.
Technical restoration means, above all, the reduction or elimination of technical interference (rustle, clicks, pops, etc.) due largely to the wear or degradation of the original audio carrier, but without altering the sound spectrum, that is to say maintaining the quality and sound characteristics of the original recording.
Artistic restoration means, instead, a more selective operation, with different aims, to be established by the user at the beginning of the work. The reasons for opting for a restoration of this type may be commercial, scientific or for other considerations.