I want my mac to stop talking to me - verbal reminders

My Mac verbally reads my reminders and calendar events out loud. It's in the most annoying and jolting voice ever.

I want this to stop.

My "voice over" feature is not on.

My notification preferences don't have a "silent" feature. You can turn them off completely, but I don't see how to get my mac to stop reading them out load. They even get read out loud when I'm listening to music or on Skype, or recording a radio show, etc. It's embarrassing and unprofessional and jolts me out of mediation and massage.

I like seeing my reminders, but I don't want to hear them.