On 8/26/16 4:39 PM, Richard L. Hess wrote:

> I listened to the clip and then read all the following comments. I had 
> exactly the same thought as Ted. Most of the burbles start with an 
> increase in pitch which indicates a slowing down during recording. My 
> thought was an overly wide tape catching in the guides, but reel 
> flanges or other annoyances could cause it. 

The warbles show up quite clearly in a spectrogram (I'm using Izotope 
RX5).  Each warble starts with a sudden upward change in pitch, followed 
by a damped sinusoidal pitch oscillation with a period of about 40 
milliseconds.  Immediately following the initial pitch change, there 
appears to be a slight loss of tape to head contact for about 10 
milliseconds (there's a brief dropout which affects only frequencies 
above about 2 kHz).  Sure does look like the tape was jamming in the 
recorder.  If this was happening during playback, a) the initial pitch 
jump would be down, not up, and b) I think you'd see a very obvious 
mechanical disturbance of the tape break arm.

-- John Chester