Tuesday, July 13, 2010

Transcription Mystery Disc #61

The disc here was in surprisingly good condition.  It is a 12-inch acetate starts at the outer edge and spins at 78 rpm with several tracks on each side.  It comes in two very different segments. First G.K. Paterson dubs a Spanish language lesson tape (presumably lesson 1-B) but it's not dubbed line-in. From the audio quality it's pretty clear that he just puts the mic near the speaker. But the EQ loss was pretty predictable. What it sounded like was a phone call, so I knew that the easiest way to remove noise was to chop out the audio outside that range with a bandpass filter. I chopped the frequency response to between 350 cycles and 3,500 cycles per second.  I tried it again at 500 and 2500 and found it almost indistinguishable but significantly more clear as some surface noise obviously exists above and below that frequency.
The recording of his own voice reading the lesson is much clearer. I used only one of the readings, and selected the clearest one. That portion of the audio leads as it has the best fidelity.the recording overall isn't a huge mystery compared to the other discs I've ripped. We have a last name, and a first initial, no school or lesson book name but that may be too much to ask. Date is probably mid 1940s based on the Yellow audiodisc label, but I have seen 10" discs with the same label used into the 1950s.  I'd err toward the latter based on the condition.