INTRODUCTION
As our cultural heritage continues to be made up of more and more audiovisual forms of expression, our archives are becoming filled with historic audio recordings that we, as archivist, must preserve and make accessible. Recordings of our musical artists, poets, writers, news, speeches & spoken words of our politicians and great thinkers, radio broadcasts and field recordings of many cultures, private and public dictation, intelligence recordings and all commercial record releases make up just some of the major categories of our historical recordings.
The Recording Preservation Act of 2000 made sound preservation a matter of
national policy to “maintain and preserve sound recordings and collections of
sound recordings that are culturally, historically, or aesthetically
significant… " (Public Law 106-474; H.R.4846). A new advancement in the preservation of audio has emerged called
Sound Imaging, which tackles the preservation of audio carries that are made
from grooved audio media such as cylinders and discs and the first 70 years of
our audio heritage. This advancement employs the use of photosensitive sensors
in optical probe cameras to acquire data images of audio carriers, which can be
translated into sound.
A BRIEF HISTORY OF SOUND IMAGING
The first instance of sound imaging is credited to Édouard-Léon
Scott de Martinville or Leon Scott, a French printer and bookseller from Paris who
patented the first known sound recording device in 1857. He called his machine
the Phonautograph and the result created
a visual image of sound on paper. Sound traveled through the horn of a cylinder that
vibrated a diaphragm at one end of the horn. A stiff brush attached to the diaphragm
would move across a rotating cylinder covered with lampblack or blackened paper
from the sound vibration. This
created an image of the sound. He also used flat discs to trace the lateral
motions of the stiff brush. However, there was no way to playback these
“recordings” be they disc or papers.
Thomas Edison was the first
inventor to create the “Phonograph” machine
that actually played back sound in 1877. He used a tinfoil rather than paper to
emboss the audio signal and a stylus to playback or retrace the waveform. Charles
Summer Tainter and Alexander Graham Bell developed the “Graphophone” from 1881-1886, which used a wax like cylinder as its
audio carrier. Emile Berliner invented the “Gramophone”, in1887 using non-wax “metal plates” or discs as the carrier
which was photoengraved with lateral grooves. The race to invent better
mechanical recording devices and their audio carriers had begun.
The “metal plates” became playable
discs or records that we can listen to over and over again. The audio recording and playback
industry is now over 130 years old.
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| Scott’s Phonautograph |
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| Audio tracing on embossed on paper |
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| Edison’s Phonograph |
The audio cylinder continued to
evolve utilizing different sizes and physical properties. Eventually 78rpm
records became the standard for commercial audio carriers followed by the “micro
grooved“ LP records we are still listening today- despite the advancements of
optical media such as audio CDs or digital file media such as audio wav and mp3
files.
The problem for archivist is how to
play back these grooved audio recordings without damaging them and how to play back
recordings that are damaged and sometimes broken. Thousands of recordings were
unavailable because of these kinds of conditions, prompting Congress to stress
the need to develop new methods of preserving audio.
Sound imaging is a new method to hear the “sound”
embedded in a grooved sound carrier.
No stylus or needle is used in this method and thus no damage or
“playback wear” is done to the existing audio carrier by the stylus. The
grooved surface of the sound carrier is imaged and then translated into audio
through the use of specialized camera and that can take very small images or
photos of the grooves. A high intensity laser beam is shown on the surface of
the audio carrier. Those images are then translated into a digital audio wav
that can be played back for humans to listen to. In the case where the audio
carriers are damaged or in pieces, sound imaging can image the parts and knit
them back together in software to again be heard.
Although still in its infancy, sound imaging had its’
early roots in the 1960’s when reflected light patterns began to be used to
characterize test records and researchers studied grooves with infrared
photo-metry in the early development of the compact disc or audio CD. Laser light
improvements developed throughout the 1970s with the first laser made CD player
coming out in 1980. In the 1990’s a laser turntable was developed in Japan and
throughout the 2000’s laser reflection was tested to replace the traditional
styli with light.
VisualAudio is the first optical audio signal retrieval
system based on analog high-resolution photography and subsequent fill scanning
and was developed by Dr. Stefan Cavaglieri at the College of Engineering and
Architecture of Fribourg, Switzerland.
Beginning in 2001, their aim has been to archive discs that are
deteriorating by storing their scanned sound images on photographic film that
support a long life span.
Dr. Carl Haber of University of California Berkley
Lawrence Livermore Labs heard a piece on public broadcasting about the loss of
historic recordings and thought his work with precision optical
metrology systems for the ATLAS experiment in Cern, (which observed the
particle called the Higgs Boson) could become the basis for inventing a system
to scan grooved audio carriers. Optical metrology uses “electronic
imaging, image processing and precision motion control to derive quantitative
information about the size and shape of physical objects”. [i]
The basic research for this work was carried out in 2002-2004. Dr. Haber called his imaging system IRENE (Image Record Erase Noise, etc) and with
Dr. Earl Cornell has developed the IRENE imaging process.
In 2005 the National Endowment for
the Humanities funded further development of disc imaging for use at the
Library of Congress and the first disc imaging system was installed at the LOC
in 2006. The Institute of Museum and Library Services funded a 3D imaging
system for audio cylinders that was installed in the Library of Congress in
2009. Follow up grant funding by
IMLS from 2009-2012 helped create more systems for imaging more collections,
notably one in India for disc imaging, and carried out a series of special
projects on small collections that let us hear audio from the earliest days of
recorded sound, creating significant access to the research community in
particular. Many other institutions supported this research including the
National Archives, The Department of Energy, The Mellon Foundation, the
Smithsonian Institution, etc. See index listing for some of these special
historical audio projects. The first imaging system that made this system
available to the public began serving the preservation community at Northeast
Document Conservation Center in 2014.
A recent Sound Imaging Conference in July of 2015 at
the Library of Congress highlighted the advancements in imaging currently
underway in Britain headed up by Dr. John McBride and by Sweden’s Dr. Ottar
Johnson, among others.
HOW IT WORKS
Sound Imaging is a general term used for profiling the
surface of grooved mechanical sound carriers through the use of high-resolution
digital microphotography to capture a representation of the grooved disc
surface. Called optical surface profiling, microphotography captures or “maps”
the sound carrier surface, creating 2 dimensional or 3 dimensional data images.
HOW IT WORKS
The IRENE has two methods of doing this for two
different grooved audio carriers. Two-dimension microphotography mapping is typically
used for laterally cut sound carriers such as disc or records. The imaging is based upon high-resolution
digital microphotography and captures a two-dimensional (2D) representation of
the disc surface. The aim is to address the high-speed capture of the revolving
disc. A light source is needed on the surface to illuminate the grooves for the
camera and a laser sensor measures the distances of the audio carrier’s grooved
surface.
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| The camera takes image of record as it turns, imaging the grooves |
Three-dimensional mapping is used for vertically cut
sound carriers such as cylinders. A confocal micro photographic camera, as used in microscopy,
takes 180 points of the depths on the audio carrier’s grooves. A laser beam measures the distances of the audio
carrier’s grooved surface in order for the camera to focus correctly on the microscopic
surface.
The camera
takes multiple points of the cylinder’s surface, resulting in black and white
data file of cylinder’s surface.
Once high-resolution mapping is made of these 2 kinds
of grooved sound carriers, computer-processing methods are applied. The edges of each groove are
found by focusing on areas of high-contrast between light and dark in the
image. The flat bottoms of the grooves and the spaces between tracks appeared
white on the data images, while the sloped sides of the grooves, scratches, and
dirt look black. The data image is analyzed to create a digital audio wav form for listening. The preservation master is the data file
of the image; the access master is the audio file.
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| View of Grooved disc or ‘record’ |
A numerical or mathematical algorithm, executed on
this mapped image of the sound carrier, reconstructs the recorded sound with no
contact of the actual sound carrier. This maintains the original sound
carrier’s physical properties without anything actually touching the recording
medium, (and possibly degrading it) creating a new method of preservation for
these sound carriers. Additionally by mapping the damaged or broken parts of
these sound carriers it is possible to actually “hear” what is on them again.
Librarians, archivist, museum curators and cultural historians have been
waiting for an opportunity to be able to recover these damaged and “unplayable
“ recordings. With sound imaging, we now have the possibility of doing just
that.
Some of the issues surrounding the advancement of sound imaging are speed in transfer time for this process, lack of trained audio personnel to utilize this system, and lack of further development money to make the system more standardized for audio engineers or “user friendly”. Multiple-cylinder scanning, now 3 cylinders at a time, is currently under way and NEDCC is training multiple users on the system in 2016. Although in its infancy, sound imaging is an audio preservation development that will be advanced and utilized in the future in ways that may be difficult to imagine.
Some of the issues surrounding the advancement of sound imaging are speed in transfer time for this process, lack of trained audio personnel to utilize this system, and lack of further development money to make the system more standardized for audio engineers or “user friendly”. Multiple-cylinder scanning, now 3 cylinders at a time, is currently under way and NEDCC is training multiple users on the system in 2016. Although in its infancy, sound imaging is an audio preservation development that will be advanced and utilized in the future in ways that may be difficult to imagine.
Works being done at MIT with microscopic cameras, even
regular cell phone cameras, are imaging and reproducing sound recorded in
objects, giving way to the idea of embedded audio in the all grooved objects in our
collections. It is hoped that soon we will be able to start retrieving audio
embedded in our collection’s objects- giving way an even greater audio
collection and cultural heritage. For instance we could listen to a ceramic pot
that had Latin being spoken when it was made and hear this “dead” language, as
it was spoken thousands of years ago. I urge everyone to watch the 4 minute
video explaining some of MIT’s sound imaging current work.
CONCLUSION
We have steadily gone from the evolution of sound recording
and photography as separate entities to a blend of both technologies that
document our cultures. It is up to archivist to preserve and to create access these artifacts from the evolving sound
imaging pathways that allow us to do so.
Bibliography
Cornell, E.W. ,.Fadeyev,V., Golden,M. .Haber,,C.,Nordmeyer,
R.(2009). “3D Optical Scanning of Mechanical Sound Carriers
Technical Description Revised” Retrieved from http://irene.lbl.gov/IRENE_2D_3D_Examples.html
Davis, A. (2014). The Visual Microphone: Passive Recovery of Sound from Video
Retrieved from: http://people.csail.mit.edu/mrub/VisualMic/
Watch: https://www.youtube.com/watch?v=FKXOucXB4a8&feature=youtu.be
Haber,C. (2014). “New Technologies to Preserve and Access Historical Recorded Sound
Hardesty, L. (2014) “Extracting Audio from Visual Information
Algorithm recovers speech from the vibrations of a potato-chip bag
filmed through soundproof glass.”. Retrieved from:http://news.mit.edu/2014/algorithm-recovers-speech-from-vibrations-0804
Holton, Conard C. (10-01-2007). “Rescuing
recorded sound from silence”. Retrieved from http://www.vision-systems.com/articles/2007/10/rescuing-recorded-sound-from-silence.html
IRENE Sound Reproduction R&D Home Page Irene.lbl.gov
General information
General information
Johnson, O.,
Sotozer, S.. Bapst, F., Ingold, R. (2007). “Detection of the Groove Position in Phonographic Images”. Fribourg
Univ., Fribourg Conference: Image Processing, 2007. ICIP 2007. IEEE
International Conference on, Volume: 6 Retrieved from https://www.researchgate.net/publication/4289187_Detection_of_the_Groove_Position_in_Phonographic_ImagesDOI
Krotz, Dan (2004). “From Top Quarks to the Blues:Berkeley Lab physicists develop way to
digitally restore and preserve audio recordings” Retrieved from
http://www2.lbl.gov/Science-Articles/Archive/Phys-quarks-to-blues.html
Schoenherr. S.E. (2004). “Leon Scott and the
Phonautograph”. Retrieved from http://www.aes.org/aeshc/docs/recording.technology.history/scott.html
Reference:
To listen to recovered archival
sound check out: “Examples from the Berkeley Lab
Recorded Sound Restoration Project” Last Update
23-September-2013. Retrieved from:
http://bio16p.lbl.gov/2013-examples.html
Footnotes:
[i] Haber,C.
(2014 )“New
Technologies to Preserve and Access Historical Recorded Sound
June 2013”. Retrieved from:
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