In that case, the most common cause is a defective capacitor in the audio stage.
I don't have access to a BC895XLT schematic. In several older Uniden BC800XLT scanners, I replaced the 47 ufd electrolytic capacitor which was in series between the audio amplifier output and the external speaker jack. The output capacitor had gone bad and caused low volume and microphonics.
There are multiple capacitors involved in the audio stage and your radio could have had a bypass capacitor open up.
If you are not comfortable making DIY electronic repairs, send the radio out to a technician for service.