beep in Scribbler.cpp does not work for duration values greater than double 6.0 or int 7 (or 8) seconds

[David Cowden]

When calling the beep function, programs hang if double values such as 6.0 are given or integer values greater than 7 are given for duration. Upon terminating the non-responsive program with CTRL-C, this message is displayed:
/usr/include/boost/thread/pthread/mutex.hpp:45: boost::mutex::~mutex(): Assertion `!pthread_mutex_destroy(&m)' failed.