I found this online test (https://hearingtest.online/)to provide me helpful information, and I believe that its use over time by me for differential testing to monitor hearing in between visits to a professional setting will be of value. Perhaps it’d be a resource for you. It was created by audio engineer and sound designer; does not ask for email or any personal information. I found that its method for calibrating the playback volume to be interesting/effective and checked the results via and old sound level meter I had from Radio Shack from a few decades ago.
I know that online sound/tone generators and HA mfg hearing tests are also readily available. For the above I used both high quality desktop speakers and Sennheiser headphones each with good and fairly flat frequency response. When I have the opportunity to have someone else present the test sounds to me (rather than clicking things myself), I will do so. This would eliminate any tendency to “claim” that I am hearing something because I know that a sound is being presented.
As I understand standard tone threshold testing procedures scoring of the test and determination of threshold would be at least two out of three correct answers at any freq and volume setting; meaning correctly indicating hearing sound very close to the onset of it and indicating it stopping very close to its termination. As the above website suggests for retesting one must duplicate all characteristics of the environment especially making sure that fan noise from computer or HVAC is not present. I don’t know for sure but if one has the option to use above not via a smartphone it probably would be more accurate. Personally I did find that results from above matched those of recent professionally determined audiogram.
The above test might be of particular value (to get ball park handle on extent of their hearing loss) to those who are new to HAs and have not yet had a professional hearing test in sound proof booth, etc.
Disclaimer: I have no affiliation with the developer or the website, and am not offering medical advice to anyone who might read this.