Hey, Baz. This might be a tape for the TI99/4A but I'm not sure. The cassette itself is branded Texas Instruments. The ASCII Burn In Test may not. I'll ask around my TI friends, see if they recognise something.
As you say, without loading it we're all a bit in the dark.
I know what Speccy, ZX81, Beeb, Atari and Oric tape loading sounds/bleeps and screeches sound like so what I might do is listen to this - see if it's familiar - and if it isn't - RECORD it and upload it here...
One of you guys might then recognise the series of whistles, screeches, beeps and howls and say - YAY! I know that sound - it is a program for the "XYZ 999" and then, perhaps, we are a little nearer in solving our mysterious tape conundrum...?
ABOVE: What could be on the mysterious Baz T.I. ASCII burn in tape - Top of The Pops or sweet F.A.?