A complete set of sound files for the speed-building tests (and a desire to add a feature to the program — put codes in the text to change speed within text — it might have been faster than piecing together bits from several ssml files).
The zip file is about 18MB.
If you find a mistake, let me know. I haven’t confirmed the calibration for super-low speeds. Let me know if it’s off by enough to cause a problem.