For example, the word 弟弟 dìdi which means “little brother” has the first character pronounced as 弟 dì and the second character pronounced as 弟 di .
When a character within a word has a fifth tone instead of its usual tone, the mnemonic will mention “silence” or “quietness”. We can see this on the word page for 弟弟 younger brother
That key word will additionally be highlighted with a light teal color that matches the usual color of a sound within the application. When you see this, you will know that a character has a fifth tone instead of its usual tone.