Alan Dove <alan.dove@gmail.com> writes:

> In my work, I often take notes at a meeting while simultaneously
> taping it.

Same here.  In addition to what Adam sent, i see two solutions:

1. Use org-clock-in, org-clock-out and org-clock-report. 
   
   Put the time report (C-c C-x C-r) at the beginning of the first level
   of your writing, then clock (out and) in each time you insert a new
   sublevel. Make sure clock-out is not a member of `org-log-done' so
   that you won't be prompted for a log entry each time you clock out.

2. Use an `Elapsed_time' property. Here is a quick hack that could help: