How can I set my phone to display all Wireless Emergency Alerts silently, without playing any sound? I have a rooted Samsung Galaxy Note 4 with CyanogenMod 12.1 (Android 5.1.1), and I want to silence the Emergency Alert (e.g. AMBER Alert) sounds without disabling the alerts entirely. A few places have mentioned deleting a sound file, but I can't find it in /system/media, and absolute paths I've seen are also not present (e.g. /system/media/mms)

I am asking about the built-in Android feature, not the Google Now alerts.
In the Emergency Alerts stock app -> Settings, there is an option "Emergency alert tone" with subtitle "Play a sample emergency alert tone."  When you do this, it plays the tone and a dialog says "The sound you hear now will be played when you receive an emergency alert.  The alert volume matches your phone's volume."  This indicates that you could avoid the alert sounding simply by silencing the phone.   There are also apps available for managing the volume settings according to other criteria.