First of all, very few people are actually, clinically tone-deaf.
It means they have a neurological condition that renders them totally unable to hear differences in pitch.
People who are truly tone-deaf can’t even hear the pitch differences in speech, for example, whether someone’s voice is going up when asking a question, or staying even while making a statement.
Do you have trouble discerning the different emotions in people’s voices when they’re happy, sad, or goofing around? If you’re okay in that department, the good news is that you’re not technically tone-deaf, and there’s a lot you can do to improve your singing.
Most people who can’t sing on pitch are simply suffering from a lack of training and practice. Some people need more exposure to music than others to master the ability to discern and then hit the right notes.
While for some of them it may be a difficult process to learn, it can be done.