On October 27th, heritage organisations across the world will join in celebration of World Day for Audiovisual Heritage. Founded by UNESCO in 2005, World Day for Audiovisual Heritage (WDAVH) is an international day with the aim of celebrating audiovisual heritage documents and raising awareness of current risks that jeopardise their long-term preservation.
What is audio visual heritage?
Audiovisual documents include moving image, such as films and television programmes, and recorded sound, such as radio programmes, music, oral history interviews, and recordings of nature. Norfolk Record Office safeguards many forms of audiovisual heritage documents and is home to both the East Anglian Film Archives, and a substantial sound archive.
Norfolk Record Office is the East of England hub for the national audio preservation project Unlocking Our Sound Heritage, one of ten UK wide heritage organisations working alongside the British Library to digitise the UK’s rare and at-risk audio archives.
Why are audio archives at risk?
Audio archives may include a wide range of formats, such as reel-to-reel magnetic audiotape, compact cassette tape, MiniDisc, CD, vinyl, or shellac discs. These formats vary not only in the materials that they are made from, but also in the playback equipment that they each require.
One of the main risks for audio archives is technical obsolescence. Technology is continually progressing and developing, and as formats become outdated the playback equipment that they require ceases to be manufactured. Each format therefore has a finite window of time in which it will be able to be played, as the playback equipment becomes increasingly more difficult to obtain, maintain, or repair. Across the world, heritage organisations have been carefully stockpiling equipment, spare parts, service manuals and other accessories that have been or shortly will be discontinued, and ensuring the retention of maintenance and operational skills.
It is estimated that there is a ten to fifteen-year window for safeguarding at risk sound recordings before irremediable loss occurs due to the obsolescence of playback equipment. The challenge for heritage organisations is to digitise as much existing material as possible without compromising quality or meaning, to ensure that audio archives are preserved for future generations
Another risk that threatens audiovisual documents is the physical decay of the carrier. Unlike printed or handwritten text which may remain fully human-readable even when damaged, damage to audio recordings will result in a loss of information such as a glitch or skipped track, or in a worst case scenario the recording being totally unreadable by playback equipment. The protection of the carrier (e.g. a disc or magnetic audio tape) is paramount to the preservation of the recording, and poor handling, poorly maintained equipment or poor storage can result in irreversible damage.
Many audiovisual carriers, such as magnetic recordings, have relatively short life expectancies due to their physical composition, and are prone to natural deterioration and decay over time. Preventative conservation measures must be put in place to monitor and delay the decomposition of the original carrier, and the most high-risk cases must be prioritised for digital preservation to ensure that the audiovisual content is transferred from the jeopardised carrier.
The sound archives at Norfolk Record Office are preserved within a designated tape store in the Record Office strong rooms. Audio formats such as magnetic audio tape require different optimum conditions for long term preservation to that of paper or parchment, and so having a separate store allows for the relative temperature and humidity levels to be maintained at a different level to those of the main strong rooms.
The audio archive holdings are checked for any signs of natural decay, and occasionally specialist treatment must be carried out to stabilise at-risk sound carriers. For example, magnetic audiotape is prone to a natural deterioration of the binders (the glue) that holds the magnetisable oxide particles to the tape. Over time the binders absorb moisture from the air, causing them to breakdown and rendering the tape unplayable, a condition referred to as ‘Sticky Shed Syndrome’. This can be temporarily reversed by a process called ‘baking’ the tape, a temperature controlled process of removing the moisture from the binder to allow for the tape to temporarily be returned to a playable state in which it is necessary to create a copy of the threatened audio.
Another reason why it is necessary to digitally preserve sound archives is accessibility. Today, the most practical means of making a sound recording available to members of the public is via a digital copy of the original, listened to either in-situ at a heritage organisation or online. It is likely that future viewers and listeners will access audio heritage in a purely digital environment, and so it is important that audio archives are digitised for both preservation purposes as well as for ensuring that they are compatible with modern technology to allow for public access.
To discover collections that have been digitally preserved at Norfolk Record Office, follow the Norfolk Record Office social media channels for sound clips and behind the scenes footage.
YouTube: Norfolk Record Office
In this video, Cataloguing Manager Helen Busby shares extracts from one of her favourite collections, the audio archives of the British Antarctic Survey:
So far, Unlocking Our Sound Heritage nationwide has digitally preserved over 200,000 rare and at-risk sound recordings. To find out more information about what is happening in Unlocking Our Sound Heritage hubs around the country, visit the British Library Sound Heritage Twitter page: @BLSoundHeritage
I would be interested to know in what format you keep the digitised recordings and how you plan for the time when that format becomes obsolete.
Hello Roger. We digitise all recordings using WAV file format at 24 Bit and 96 khz. When planning the Unlocking Our Sound Heritage, a UK wide survey was issued to determine where audio archives were held, the contents of the recordings, and the vulnerability of the formats. By surveying collections, we were able to decide which recordings to prioritise based on their level of vulnerability and the uniqueness of the content. This process included looking at the availability of play-back equipment and spare parts, and assessing the fragility of the physical carriers (e.g. magnetic audio tape, or disc), prioritising those that were in the worst physical condition.