Restoring the Past: A Psychoacoustic Study of Historical Audio Enhancement

Historical audio restoration differs fundamentally from modern enhancement tasks. While contemporary systems often optimise for signal fidelity and perceptual clarity, restoration of century-old recordings must additionally consider listener expectation and perceived authenticity. Early recordings are characterised by severe, non-stationary noise and extreme bandwidth limitations, making conventional objective evaluation challenging.

In denoising tasks, many standard metrics rely on the availability of a clean ground truth, which does not exist for archival material. Elevated and dynamic noise floors further complicate reliable quantitative assessment. In bandwidth enhancement, objective measures typically evaluate spectral reconstruction accuracy, yet such metrics do not fully capture how listeners perceive timbral balance, naturalness, or historical plausibility.

To address these limitations, this study combines objective analysis with structured listening tests to evaluate denoised and bandwidth-extended speech and musical recordings from the early 20th century. Both blind and open listening tests were employed. Blind tests aimed to minimise contextual bias and assess perceived audio quality across restoration stages. Open tests provided guided evaluation criteria, allowing participants to reflect on clarity, naturalness, and authenticity.

The results highlight a measurable gap between statistical signal fidelity and human perceptual judgement. In extreme restoration scenarios, improvements indicated by objective metrics do not always correspond to listener preference or perceived authenticity. These findings underscore the importance of human-centred evaluation in archival audio restoration and suggest that perceptual and contextual factors must be considered alongside quantitative measures.

The talk will be followed by a short Q&A session.

As usual, we will be heading to the pub after the talk to catch up and continue the conversation. It would be great to see as many people in person as possible.

Those planning to attend in person MUST register for security access. The link to register for in person attendance can be found below:

https://www.cpdtag.com/app.php?event=BF787092E50B9587194EAD465EF953A

Registration for in person attendance closes on Monday 7^th September at 17:00.

Please arrive at 5.45pm for prompt 6pm start. The nearest Tube stations are Aldgate East and Aldgate.