When connected to a phone, the phone notifications take precedence over hearing amplifications. This is so that you don’t miss any important phone calls. Therefore, we recommend changing the phone settings to turn off key tones such as touch sounds, keyboard taps, and some notifications according to your preferences. Phone calls will still take precedence, but this will greatly reduce the number of times the hearing is "interrupted".
Settings for phone notifications behavior is usually accessed through the smartphone’s "Settings" menu, in a section called “Sounds and Notifications”.