Tomás Ó Máille Wax Cylinders - Guide to Digital Audio Improvement

The Library is in the process of publishing digitised versions of Tomás Ó Máille's wax cylinder recordings. Ó Máille (1880-1938) was the inaugural chair of Irish at UCG, appointed in 1909. The collection consists of roughly 33 hours of content that dates from 1929 onwards and contains audio recordings of Irish speech, singing, and storytelling. The contributors to these recordings were from Achill and Aran Islands, and all over Connacht and county Clare.

This work is part of a wider collaborative effort to enable research by digitally and openly publishing the audio of the Tomás Ó Máille wax cylinders. Work is also underway to create a Tomás Ó Máille exhibition. Dr Deirdre Ní Chonghaile is the curator of the exhibition. Lillis Ó Laoire, Professor of Irish in the School of Languages, Literatures, and Cultures, NUI Galway is the academic lead for the programme of work on Tomás Ó Máille. Dr Cillian Joy, NUI Galway Library, provides project management and technical direction.

With great thanks to Roinn na Gaeltachta who provided capital grant funding for the wax cylinder digitisation.

Benefits of improving the digital access version

• Easier to listen to the audio
• Researchers find it easier to understand the content and put it into context
• Researchers are able to more easily explore the research potential of the collection
• Potential increase in the ability of technology to interpret the audio.

It was fascinating to hear and listen to these voices from the past, however some of the voice recordings were more inaudible than others. This is what started our conversation around how we could improve the audio, and make it more listenable for users. We believed it would be worth the effort to go through each wax cylinder and attempt to decrease the background noise and distortions. Some of the cylinders also featured multiple recordings on them, so these were then divided into their separate tracks, which makes it simpler for navigation and listening in general.

The collection of 398 wax cylinders is very susceptible to degradation from mould and cracking. Because of the fragile nature of the wax cylinders, some of the digitised audio files are not as clear as others. To address this, we are working on improving the audio quality of the access copy of these recordings using digital audio workstations. The imperfections heard in these recordings can also be due to the grooves in the cylinders being dirty or worn, like how a vinyl record can sound fuzzy after many years.

Below, you will find the process and workflow that is used to make these improvements and to make the audio more listenable. This is what we found worked best for these wax cylinder recordings, but this process can apply to all types of audio, and these techniques could be used to remove background noises from an interview recording for example. 

Step 1: Preparation

Fig. 1

The first step of this process is getting the WAV audio file into the Adobe Audition workstation. You can simply drag an audio file into Audition, and it will appear in the workstation.

In figure 1, we can see an example of a WAV file, that is a digitized version of one of Ó Máille's wax cylinders. Towards the top of the screen will be a waveform of the audio (in green) and also displayed is the spectral frequency display (orange and purple spikes), which shows us the noise in the tracks.

This file contains 3 separate tracks, the slight gaps which are highlighted by the white circle show us the gaps between these tracks.

Fig. 2

To work on these files separately, it is useful to open a new audio file for each separate track. This can be done by pressing File > New > Audio File.

It should then be titled by adding an underscore and 01. Any files after this should be titled with an underscore and 02, 03, 04 etc.

This is to make the organising of files easier and is a clear way of showing numerous tracks that were recorded from a single wax cylinder.

Step 2: Identifying Noise / Imperfection

Fig. 3

This track is now ready to be worked on and improved. Every track will be different, and will require a slightly different process, but the same principles should apply to majority of audio.

The track in Figure 3 has been zoomed in on to the point where individual sounds and imperfections can be seen in the frequency display (orange/purple spikes).

The Ó Máille cylinder recordings were consistent in their defects, and could always be identified by similar spikes in the spectral display seen in Figure 3.

Zooming in and out can be done using the controls at the bottom of the display (Fig. 4).

Fig. 4

Fig. 5

The spike is representative of an imperfection or noise in the audio, and the idea here is to give the software a sample of the noise you want removed, and it will then attempt to remove that noise from the whole track.

To highlight a section of the audio like this, use the letter I on your keyboard to mark the ‘In’ point and the letter O on your keyboard to mark the ‘Out’ point.

As shown in Fig. 5, the sliver of audio that is highlighted is the noise that we want to sample, and then have removed from the track as much as possible.

Once the noise for removal is highlighted, we click on Effects > Noise Reduction/Restoration > Capture Noise Print (Figure 6).

Fig. 6

Step 3: Removing the Noise

Fig. 7

To begin the process of removing this noise from the track, we then highlight the entire track. This could be done by choosing the ‘In’ and ‘Out’ points at the beginning and end of the entire track or use a highlight all shortcut (Cmnd + A when using Mac, Ctrl + A on Windows).

Click on Effects > Noise Reduction/Restoration > Noise Reduction (Process).

This will open a window that shows the controls of this process, and where the noise reduction effects can be fine-tuned. This is the aspect of the workflow that will change for every track being improved, and some audio tracks will require more use of effects than others, and because of this it can require some trial and error. The settings shown in Fig. 8 are a good place to start off for audio files with very high distortion like these wax cylinders.

Once satisfied with the results of the effects, click Apply and the changes will be made to the track, removing the undesired noise.

Fig. 8

Step 4: Boost Volume and De-Clipping

The next step is to then boost the audio to a desirable level. The amount the volume is boosted will depend on each individual case, and it must be kept in mind that boosting the volume will also boost the sound of imperfections or noise that may remain in the track.

Volume can be tuned with the dial shown in Fig. 9.

Fig. 9

Once the audio is boosted this can create spikes in the volume that need to be clipped.

To open the De-Clipping tool, click on Window > Diagnostics. Then select De-clipper from the drop-down menu like in Fig. 10.

Highlight the entire track, click Scan in the De-clipper window, and click Repair for these clipped sections to be reduced to usable levels.

You may need to listen over to the track again and keep adjusting volume and de-clipping until you are satisfied with the state of the audio.

Fig. 10

Step 5: Export

As shown in Fig. 11, the next step is to click File > Export > File. The file can then be named and a location for the file chosen.

Fig. 11

Examples

Below are some examples of audio before and after this process has been performed on them.

This blog was written by Eimhin Joyce, who works on the Digital Scholarship team in the NUI Galway library. If you need help on a similar project or have any questions related to this work, feel free to contact him at eimhin.joyce@nuigalway.ie.