Your TV or set-top box might be using a secondary audio signal.
CBC News Network provides distribution for Accessible Media Inc. (AMI) Audio on one of its audio channels. AMI Audio is a service, much like a radio station, specifically programmed for people who are blind or have low-vision.
If you are hearing AMI Audio or Described Video, it might have been inadvertently activated via the audio or language setting on your TV or set-top box
To turn off the service, you need to turn Secondary Audio to "off", or set your audio to "stereo". There may be a button labelled SAP on your remote control. If not, you may have to go into the audio settings of your TV or set-top box. Consult your owner's manual for more details.