A workflow and novel digital filters for compensating speed and equalization errors on digitized audio open-reel tapes

This paper presents a workflow and novel digital filters for compensating speed and equalization errors that can impact digitized audio open-reel tapes. We examine three frequent cases of mismatch between recording and reproducing standards: NAB 3.75 ips - CCIR 7.5 ips; NAB 3.75 ips - CCIR 15 ips; NAB 7.5 ips - CCIR 15 ips. Three MUSHRA-inspired tests (”sets”) containing ≥ 21 participants were used to perceptually assess the workflow and digital filters, using excerpts of music and voice. The results indicated that the digital correction filters performed well, although the electroacoustic stimuli in Set C provided mixed results, suggesting that the style of the music used in perception tests should not be overlooked.