Audio is one of the most difficult types of materials to care for, because of playback obsolescence and fragility of original format. Most audio formats are also easily damaged and once they are damaged they are very difficult to recover. Many audio archives specialize in restoring audio materials as well as preserving and transferring them, since without restoration the transfer will not reflect the complete recording. Be very careful with your audio, and since it is extremely susceptible to environmental damage, try to keep it in a space that has good temperature and humidity control.
One of the major challenges with audio materials are their ubiquity, particularly the fact that audio was often used for original and unique materials like recording oral histories, live concerts, or meetings. These materials have incredible cultural value, but are often in very low-quality formats that were meant for home use with no expectation of longevity. With an enormous number of tapes, it is difficult to assess the preservation status of each, much less transfer them to a more sustainable medium. If you prioritize creating an inventory, that can provide some guidelines for how to decide which items should be addressed first. It can also be very hard to identify what format you have, this article from the library at Yale University gives a good timeline and brief description of many types of formats and the Library of Congress has a good overview of identification here, as well as this detailed format guide from the Preservation Self-Assessment program at University of Illinois (this also gives a good overview of video formats).
Grooved audio discs are one of the earliest audio formats likely to be found in personal and small institutional collections. Some examples of grooved audio discs are lacquer discs, LPs, aluminum discs, and cylinder recordings. They have very few inherent preservation issues, although they still benefit from good storage and handling practices. They can be easily damaged by scratches, and some discs have glass substrates that are easily broken if a disc is dropped or roughly handled.
Magnetic tape is one of the most common materials for tape, including reel to reel and cassette tapes, and without any preservation issues at all, its maximum life-span is 50 years. Most of the tapes created in the 1960’s have therefore probably already reached the end of their lives. If a tape has been duplicated numerous times, it has lost quality in that process as well.
Some particular problems associated with magnetic tape are sticky-shed syndrome where tape will squeak and shed powdery material. This can be easily fixed, but will require professional preservation intervention. Magnetic tape is very easily ripped or crushed, so it should be handled very carefully, and with gloves to prevent damage. Magnetic media is also quite susceptible to magnets, so it is important to store them away from magnetic or electrical fields. Many of the problems of magnetic audiotape also affect videotape, so make sure that you look at both of these types of collections.
CDs, particularly CD-RW is an extremely unstable format, as optical media was not created with any attention to long-term longevity. They are extremely easy to scratch and break. CDs that are pressed instead of copied are slightly more reliable, but these should always been seen as a temporary option for storage, particularly of unique information.
Playback obsolescence is an even more pressing problem in audio preservation. Because machines are necessary to play audio, it can be difficult to obtain a machine at all, much less one in good working condition. It is also important to keep the machines in impeccable order and extremely clean, otherwise they can damage the reels, tapes or discs. Many of the necessary machines can be purchased used, but it is likely they will need to be serviced. Local libraries and archives may also have these machines that you could request access to use for your collections. Record players in particular need to be properly calibrated, and you should confirm that you have the proper player for the type of record. Many modern players can play 78s, 33s and 45s, but before you attempt to play a record on a machine confirm that it is 1 speed, 2 speed or 3 speed.
Audio is a format that requires immediate attention from any collection holders, and will likely require professional assistance, but has incredible value if it is preserved.
For more information:
WNYC Archive and Preservation Process
University of Alberta Preservation FAQ
Library of Congress- Care, Handling and Storage of Audio Visual Materials
National Archives – Preserving Audio Recordings