I'm pretty sure those pure-tone tests are always taken at absolute levels; i.e., they don't change. But I think I'll try to contact my audiologist to ask her about this.
Follow-up: I asked my audiologist, and she confirmed my understanding was correct. The presentation levels for pure-tone tests are always the same. By law, they are calibrated to a specific reference level (0 dB SPL). In other words, even though your audiograms may be administered years apart from one another, the pure tones are produced at exactly the same levels so that an apples-to-apples comparison can be made and long-term trends in your hearing can be determined.
The presentation level for the speech-discrimination portion of an audiogram, on the other hand, is arbitrary. Some people's hearing distorts when the volume is too high in their headphones, while others experience actual pain if the pre-recorded voice is too loud. It's up to the audiologist to set the level they feel is both valid and most comfortable for each test subject.
In looking over my past test results, I have determined that 80 or 90 dB is the best presentation level for my "speech-discrim" tests. Any louder hurts my ears and causes the sound to distort on my AN side. Any lower, I have trouble hearing most of the words. (To make a point through hyperbole, if they lowered the presentation level 1000 dB, I -- or anyone else, for that matter -- wouldn't be able to hear
any of the words, resulting in a speech-discrim score of 0%. So below a certain level, the presentation level does matter!) I'm not going to leave the presentation level solely up to the audiologist in future speech- discrim tests. I plan to suggest they use an 80 or 90dB presentation level for optimal comfort and most-valid results.
Best wishes,
TW