That is assuming sentences are defined by "\n". The input line separator can however be changed early in the program, e.g.:

$/ = '.';
$snoozeTime = 10;
while( <> ) {
    print $_;
    sleep $snoozeTime;
}
[download]

But if ':' is also needed as a sentence terminator, there are a number of solutions for extracting the ':'-terminated sentences from each '.' separated chunk, especially regular expressions and the built-in function split.