Welcome to Android Central! That'll be hard to pinpoint. Go to your App Manager and look through all installed apps--see if any seem suspicious. If this only started recently, try uninstalling your most recently installed apps one by one, and see if it goes away.
Thanks for that but it is only a new phone...seriously, It can be anywhere or anytime and this little voice calls out HELLO and then giggles..Driving me bonkers..
If it's a new phone, then you may want to do a factory reset (making sure to backup or sync your important data beforehand). After the Setup Wizard is finished, go immediately to the Play Store and stop any app that might be automatically installing. Then reinstall apps one by one, and watch for the return of that voice.