This could mean the speaker volume control is turned all the way down (on the back) or there may be a problem with the speaker.  If the speaker volume is set correctly and you have a multimeter, set the meter to measure resistance and measure across the two wires of the speaker.  A good speaker will measure somewhere between 80 and 100 ohms.  If you get something much higher like 1K ohm, 1Meg ohm or “OL”, the speaker is bad.  Replacement speakers are available through technical support for all of our models.