Mariah Carey, Charlotte Church and Eric Benet--the thing all of these singers have in common is their ability to reach high notes. If you are longing to be like these artists and many others who can trounce across the highest heights of their vocal register without stumbling, then you need to train your voice to do it. Training your voice to sing high notes will happen quickly if you are persistent in your pursuit, though everyone's body and voice is different and will make improvement at its own pace. However, by following the steps below, you will speed up your vocal "metabolism." Minimal to maximum improvement can start to be seen in as little as a week, but will definitely be noticeable after a few weeks of consistent practice.
Heat up the pipes. Everyone knows that before you do any type of exercise it is best to warm up first. Apply this logic to your voice as well when singing. Start with a short song, such as the "Happy Birthday" song, and progressively increase the key of the song from the lowest in your range to the highest in your range.
Stretch your vocal range. One of the keys to singing higher notes with your voice is to slowly but surely increase the workload you place on your vocal chords. Your vocal chords are a muscle and can be out of shape, generally being noticeable when higher notes that are outside of your normal speaking voice are attempted. Practicing high notes everyday without overdoing it will set you on course to singing higher notes in a very short amount of time. Be careful, however, not to do too much too fast because this can strain your vocal chords and cause you to lose your voice. During the first week, practice no more than 2 hours of actual singing daily so you avoid straining your voice. Start by singing songs that are well within your vocal range (soprano, alto, tenor and bass) and offer a few points that are higher than you usually sing. After you can sing these notes comfortably, move on to more challenging songs that offer more higher notes than you are used to in your own vocal range.
Swallow instead of clearing. Bad habits such as clearing your throat or hacking excessively can damage your voice. It is better instead to swallow or clear your throat gently in a breathy manner. Yelling excessively is another activity that should be avoided as it can damage the voice, starting especially with the part used for high notes.
Diet to weigh in higher on the scale. You won't hear this often, but you will need to have a well-balanced diet and good eating habits in order to weigh in higher on the scale--the vocal scale, that is! Drinking lots of water and tea and eating plenty of fruits and vegetables can help prevent mucous from building up and negatively affecting the voice. Dairy products, fried foods and caffeine should be avoided as well, as they are not good for the voice and will make it difficult to sing higher notes if you able to do it at all.
Sleep for success. Getting enough is essential when training your voice to do anything with singing. Just as you must obtain ample rest when exercising, your voice too must rest and allow the body to repair it. How much sleep you get is also related to seeing how much improvement your voice makes. Try to sleep in a room with moist air as not to dry out your throat during slumber.