Listen only to new blocks in the chain

Would it be possible to add check boxes such that only newly generated blocks are heard, not all transactions?

This is an amazing project, by the way -- great idea, great realisation, I love to have a tab open in the background :)

The issue names no files, tests, or entry points. Start by locating the transaction and block-handling code and the audio-selection UI; the work is done when checkbox controls allow newly generated blocks to be heard without playing all transactions.

Written by the indexing model from the issue text.