Edit: After half day, my wife’s Mac started having the same problem. I have then applied the solution that I found in the Apple
Apple Releases iOS 6.1.4 For iPhone 5
Apple has just pushed iOS 6.1.4 for for iPhone 5 users, the update includes an updated speakerphone profile. At this moment thats all it seems the update changes but it is no unusual for Apple to make changes under the hood fixing security flaws and bugs and this 11.5MB update suggests this is the case.