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Surface Profiling Technologies Applied to Recorded Sound Preservation and Access

Surface Profiling Technologies Applied to Recorded Sound Preservation and Access. Lawrence Berkeley National Lab. The basic approach is to use optical measuring and image processing methods to create a digital representation of the complete record

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Surface Profiling Technologies Applied to Recorded Sound Preservation and Access

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  1. Surface Profiling Technologies Applied to Recorded Sound Preservation and Access Lawrence Berkeley National Lab

  2. The basic approach is to use optical measuring and image processing methods to create a digital representation of the complete record surface, on the computer, and then “play” it with a virtual needle.

  3. Non-Contact Digital Imaging • Preservation • Protects samples from further damage • Repair existing damage and debris through digital “touch-up” • Access • Offload many aspects of transfer to automated software • Handle diverse formats A “smart” copying machine for records Micro-photograph of shellac disc: A two dimensional image “2D” can measure lateral grooves. Surface profile of a wax cylinder: A three dimensional image “3D” is required for vertical cut grooves or to extract maximal information.

  4. Cylinder surface ridge 127-254 microns d e valley 400 mm 150 mm Disc surface

  5. 3D Scan of an Edison Cylinder cylinder 3D optical probe rotating stage translating stage Reconstruction of groove profile in highlighted region. Data shown is measured with the STIL probe. Measured data Supported by the Library of Congress and the Mellon Foundation

  6. 1) Sample at 96KHz to minimize effect of aliasing 2) Acquire sequential axial scans 3) Overall cylinder shape is due to off-center, deformation, heard as low freq rumble 4) Subtract valleys from ridges to correct for overall shape d/dt 5) Numerical differentiation to Calculate stylus velocity (Ridges provide (approx), geometrical reference)

  7. Sound Comparison • The Holy City, composed by Stephen Adams, The Edison and Skedden Mixed Quartet, Amberol 1601 • Stylus* • Optical (flat EQ) • Optical + filter + re-EQ** *Stylus version is from a modern “Archeophone” electrical cylinder player, flat EQ ** Low frequency boost to compensate for acoustic horn performance

  8. Damaged Wax Cylinders • The recovery and restoration of damaged recordings is of great interest to the archives. • Examples: • Cracked or broken: reassemble digitally • Surface mold (fungus) growth: pick good regions • Overall deformations: global shape fits • Study of damaged media is a research priority for our project. • Current activity is to study wax dictation cylinders from the estate of American author Jack London 1876-1916

  9. Damaged Wax Cylinders 1st of 12 cylinders from JL house with mold growth visible JL’s Dictaphone machines from the JL State Park Jack and Charmian London ..soon after the affair, very tragically between England and America… …the Lusitania… I wish I had time to go and read your letters…..that it opens up…but I simply cannot.…After the war is over I am intent upon going to England. And then making sure that we shall get together (period) 1st Cylinder on 3D scanner Extracted audio waveform, (preliminary analysis) Voice of Charmian London 1915?

  10. 3D Scanning as a General Tool • A preservation tool for 3D scans of cylinders, discs, and dictation belts. • With present technology this will not be fast but will provide the highest resolution digitizations available and extract the maximum information from the media Plastic dictation belt Wax cylinder with mold Shellac disc Sample data scans on various media

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