For Receiver-in-canal (RIC) hearing aids
For Behind-the-ear (BTE) hearing aids with thin tubing
For In-the-ear (ITE) hearing aids with custom domes
For regular (non-custom) domes
For custom domes or thin tube domes
Consult your hearing care provider
Check the fit and comfort
Observe sound quality and feedback
Try different sizes
It depends on your environment and your earwax production.
In general, aim for these guidelines:
Signs you need a new filter: