If I had a dollar, even a Canadian one, for every time a person has said to me that they just can't sing, I would be rich. Why is it that so many people really feel they can't sing?
There is a theory that it is actually a "brain" deficiency. Click here to read that article. This could be true and still the end of the article suggests that people could practise to get better.
I think for the most part there are some much simpler reasons & solutions.
1. A negative comment - Truly it can be as simple as someone having said to the person that they sounded badly or shouldn't try to sing. That can be very hard to overcome. If you are told that you are no good at something, you take it as truth, period.
May I suggest that we make a concerted effort to catch people of any age at doing something RIGHT. We are really good at catching mistakes and pointing them out. I feel we really need to switch our thinking and look for what is well done even if you have to wait for a long time for it to happen. Yes, you have to tell people when something isn't correct because they can't keep repeating the mistakes BUT make certain that the positive words are bigger, brighter and more important than the negatives. e.g. Stop - that was incorrect. Let's go back and make it sound like that last part of the song before where you really nailed those rhythms." Focus on the right in correcting the wrongs. Perhaps then we will have fewer people feeling badly about a mistake. For heaven's sake, if we don't make mistakes we never learn. Mistakes are KEY! How we handle them in building people up will make a difference.
2. No tone matching skills - Although this is referred to in the article I mention above, I think there are many simple steps to help people. One of the simplest is to encourage people to sing with a favourite song. It is imperative that we help people find a song that works for them. Some may be out of their range and so they will feel a failure if they use it. Or some songs have such a "muddy" sound it is hard to hear the tune. Have them give you suggestions for songs they like and perhaps play them together and figure out which ones will be best for learning to HEAR the right tones and then tone match.
If these people are in your choir, make certain they are surrounded by solid singers. It isn't easy but very do-able.
3. Not enough opportunity to sing - That is very real. If the adult never had the opportunity to sing as a child either at home or school then it will be much harder to learn the skills as an adult. Children are more ready to learn and make the necessary mistakes. Here you must create a comfortable learning environment and let the person be a child and discover music and singing.
I hope you sing all the time. Make up songs, sing along with everything. Sing to babies, dogs, children, other adults. Sing because you can. Release the negatives and sing. Ta, da!!