DIY Self-Programmers use three methods for programming their HAs to fit their specific hearing loss;
- Professionally fit hearing aids use your paper audiogram (or a digital version) to enter your hearing loss into the fitting software, and then use an additional measuring system to achieve REM/Real Ear Measurement. These settings are stored in the hearing aids that you purchased.
- Self-Programmers sometimes enter their hearing loss from the paper audiogram only. For example; When you get only a hearing test without purchasing any hearing aids, and then buy used hearing aids from Ebay.
3. Self-programmers sometimes use the In situ audiogram software feature by listening for tones played in your hearing aids, and use that measurement for entering their hearing loss. - Self-programmers can also use the In situ audiogram software feature. This is accomplished by adjusting the loudness of a tone (played from your hearing aid into your ear) until that tone becomes audible. After measuring the audible tone for each frequency (and for both ears), then the new settings (based on audible tones) can be saved into your hearing aids and database to replace your previous hearing aid settings.
You can read more about that by by clicking one of the links in this thread;
Hearing Aid Fitting DIY School and Fitting Software.