The Thinklabs One has five filter settings from which to select, from low-pitch to high-pitch to full bandwidth. You can select any two of these five filters as "Favorites." The only difference between a Favorite and any other filter is that is is quicker to switch between the two Favorites, by simply CLICKING the Filter key. However, at ANY time, you can change one Favorite to a new setting while keeping the other Favorite.
To switch BETWEEN Favorites, simply CLICK the Filter key. It will ALTERNATE the Favorites, allowing you to rapidly switch between them.
To CHANGE a Favorite, HOLD down the Filter key. The current Favorite will then sequence to the NEXT possible filter. The "other Favorite" can still be accessed by CLICKING back and forth between the "new Favorite" and the existing Favorite.
To FURTHER change the Favorite, HOLD the Filter key AGAIN and the filter setting will sequence to the NEXT possible filter and that new setting will become the Favorite.
REPEAT this HOLD process and the filter setting will keep sequencing and go back around to the LOWEST setting and then begin increasing again, cycling through all 5 options.
Once you have ONE Favorite set, CLICK to the OTHER Favorite and do the same HOLD sequencing until the SECOND Favorite is set. Now CLICK between the two Favorites, and you have your two options set. You can change your Favorites any time by simply performing the HOLD sequencing in the future.
It is not possible to have more than two Favorites. Instead, we recommend setting one Favorite to a low pitch for heart sounds and the other to a higher pitch for lung sounds, just as you have with bell and diaphragm on a mechanical device.
The factory settings for the filters on Thinklabs One are as follows (with "o" being a lit LED and "-" being unlit):
o o - - - - = Lowest pitch for heart.
- - o o - - = Mid to higher pitch for lungs