Re: [ARSCLIST] 78 rpm fragments in archaeological contexts

[Eric Jacobs <EricJ@xxxxxxxxxxxxxxxxxxx>]

PS.  The 81 msec estimate would be per 4 cm groove.  If there
     were 10 grooves on the fragment, you would have 10 sound
     fragments that were 81 msec each.  Each sound fragment
     would be separated by about 700 msec.

     This would be very easy to simulate.  Get a 78 RPM disc,
     digitize it, and then place 700 msec silent sections 
     every 767 msec (leaving 67 msec of sound).  Do this for
     about 7.67 seconds (10 grooves).  This is very roughly 
     what your sound fragment would sound like.

     If you'd like, I could build a sample for you and send
     it as an MP3 file.

Eric Jacobs

The Audio Archive, Inc.
tel: 408.221.2128
fax: 408.549.9867
mailto:EricJ@xxxxxxxxxxxxxxxxxxx


-----Original Message-----
From: Eric Jacobs [mailto:EricJ@xxxxxxxxxxxxxxxxxxx]
Sent: Monday, October 15, 2007 10:18 AM
To: Association for Recorded Sound Discussion List
Subject: RE: [ARSCLIST] 78 rpm fragments in archaeological contexts



Just some quick thoughts:

1.  Examining groove width and geometry under a microscope can
    probably identify whether the disc was recorded acoustically
    or electrically.  This gives you a very rough cut-off of the
    mid-to-late 1920s as the transition from acoustic to electric
    was taking place.

2.  A 4 cm fragment taken from the center of the disc where the
    groove velocity would be slowest, would give you a 81 msec
    sound fragment.  At the edge of the disc, that 4 cm fragment
    turns into a 41 msec sound fragment.  I don't think you could
    identify much from that.

3.  No database of 78 rpm disc chemistry exists to my knowledge, 
    and it would be costly to build and operate because of the 
    instrumentation needed to analyze the fragments.  But that 
    might be another path of investigation.  I don't know if, let
    alone how, the disc composition varied by manufacturer over
    time.

4.  Groove wear as observed under a microscope would tell you 
    if the disc was popular with the listener.  The wear pattern
    would also tell you if the listener was fastidious about 
    replacing styli regularly.  In all, I think the only real
    judgment you could make is if the listener liked that 
    particular disc.  If all the discs were well worn, you might
    be able to make other judgments - like that household listened
    to music regularly.


I'll keep noodling on this question...

Eric Jacobs

The Audio Archive, Inc.
tel: 408.221.2128
fax: 408.549.9867
mailto:EricJ@xxxxxxxxxxxxxxxxxxx


-----Original Message-----
From: Association for Recorded Sound Discussion List
[mailto:ARSCLIST@xxxxxxx]On Behalf Of Oliver Mueller-Heubach
Sent: Monday, October 15, 2007 9:16 AM
To: ARSCLIST@xxxxxxxxxxxx
Subject: [ARSCLIST] 78 rpm fragments in archaeological contexts


Hello
I’m an historical archaeology Ph.D. student at the College of William and Mary 
working on a paper for a material culture class. My goal is to create a 
methodology for using the 78 rpm record fragments commonly found on early 
20th century archaeological sites to help look at issues of class, race, ethnicity, 
and gender. Since it is very rare to find fragments with portions of the label 
surviving, the paper will focus on things like material composition, thickness,
edge-type, etc. I would like to produce a typology of characteristics that might 
correlate with different economy and deluxe labels, series, and date ranges. 
Ideally, I would like to find a way to read the grooves on the fragments to help 
identify the type of music.  Unfortunately, the fragments found are generally 
only1-4 cm. in size. The analog method that occurs to me is to cut a section out 
of a poor condition, non-archaeological 78 with a Dremel-type tool and then 
patch in the fragment and play, listening for the deviation from the surrounding 
song. This would probably prove difficult in terms of aligning grooves and 
identifying such a minute section of music, but I will be giving it a try. I have 
seen some reports of digital scanning and reconstruction of broken 78s and 
cylinders, but apparently these techniques are being applied to restore mostly 
complete recordings. Is  there a way that single record fragments could be read 
digitally to interpret the style of music (or even compare it to graphs generated 
by the practice of re-mastering old recordings and thus match the actual song)? 
I realize this is probably a long shot, but if there is a chance, it would be a great 
archaeological tool. 
Thanks in advance 
Oliver Mueller-Heubach