The sound component has a built in limit to how long a sound can last.
(Check its help.)
http://ai2.appinventor.mit.edu/reference/components/media.html#Sound
Properties
MinimumInterval
Specifies the minimum interval required between calls to Play , in milliseconds. Once the sound starts playing, all further Play calls will be ignored until the interval has elapsed.
The Player component has a longer time limit.
It also has an event that can fire at the end of what is playing.
http://ai2.appinventor.mit.edu/reference/components/media.html#Player
For exactly one minute intervals, bring in a Clock from the Sensors drawer, and use its Timer event to start the next sound. (Assuming they are shorter than a minute.)