A referring tone falls and rises, or just rises. It can be compared to a proclaiming tone, which shows that the speaker is giving new information.
Example
In the sentence ‘That guy we met at the party is my new teacher', there is a referring tone on ‘That guy we met at the party' because it is not new information.
In the classroom
Learners can analyse dialogue for shared and new information and then practise suitable intonation. They can also prepare their own dialogue, for example using the model ‘You remember...? Well, he ...', ‘No, really?' etc.
See also:
https://www.teachingenglish.org.uk/article/proclaiming-tone
Further links:
https://www.teachingenglish.org.uk/article/intonation
https://www.teachingenglish.org.uk/article/teaching-speaking-unit-4-stress-intonation
https://www.teachingenglish.org.uk/article/gobbledygook