Thanks to @Mark_Chambers great suggestion about driving, road noise, relative hearing aid and radio volumes, I’ve been able to apply the same approach to the use of over-the-ear noise-cancelling headphones in the gym and other noisy places.
The principle is effectively the same. Just imagine your streaming headphones are the radio and anything you don’t want to hear is like the road noise in a car. Turn up the volume of streaming in your headphones via your podcast player (but don’t overdo it) and turn down the volume of your hearing aids. The relative volume of what you want to hear will be enhanced, the relative volume of what you don’t want to hear will be relatively much less. And if the headphones are noise-cancelling, it works even better.
My Surface Headphones don’t block out loud noise, especially sudden noises, completely. Depending on one’s point of view, one could look at it as an advantage or disadvantage that one still has some awareness of sudden loud noises in one’s surroundings. For instance, at the gym, I still hear relative soft whfft, whftt, whfft-whfft! of someone hitting a punching bag, or plop,plop,plops, much more faintly of someone running very flat-footed on a treadmill. But by adjusting the relative volume of a streaming podcast in the headphones vs. a soft volume for the hearing aids themselves, speech from the podcast comes in loud and clear over the very muted sounds of running or boxing, same for whirring of machinery. The active and passive noise cancellation of the headphones do a major job of sweeping unwanted noises under the rug. If I were just wearing my ReSound Quattro HA’s with open domes, without hurting my ears, turning up the volume on streaming focus setting, where I hear nothing from my HA mic’s, isn’t going to do the job because of my open domes and relatively good low frequency hearing are still getting overwhelmed by loud noises in the gym going right to my ear drums.
I haven’t thoroughly tested it but the noise-cancellation features of the headphones do seem superior to anything built-into the ReSound HA’s. There does seem to be a slight quaver introduced in voices with the headphone volume up, the HA volume down - don’t know whether it’s the headphone noise-cancellation or HA distortion for the relative loud headphone volume used, e.g. - but I only notice the slight distortion if I focus on it and for having a talk show that’s easy to understand in the din of the gym with boxing, running, stair-stepping, weight clanging, people nearby trying to talk to each other loudly above the din (and add in overhead “Muzak”), I don’t mind the result at all for being able, finally, to listen clearly and easily to podcasts in very noisy environments. Also, with these relative settings, if the podcast is stopped, I hear a slight bit of hissing/fizzing noise from the ramped up headphone drivers/speakers if nothing else is coming through the headphones-and it goes away if I go back to more normal settings.