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Becoming a rock singer requires more vocal control than singing karaoke in a bar. You need to learn how to control the pitch and tone of your voice.  Sing from the stomach instead of the throat. Singing from the throat is like a speaker without a box. You don´t get the fullness of the sound. It will sound squeaky when you try to hit some good notes, especially the high ones. So, mainly use the throat as a conduit. Work on hitting high notes.  Diaphragm pressure is the key to creating the heavier vocals used by rock singers. Your diaphragm controls the air that goes through your vocal chords. Some pressure in your diaphragm can push just enough air through your vocal chords to get that heavy grit out. Practice changing the pitch. Experiment with opening and closing your throat, lips, and teeth to see how much control you have over the sound. Closing your throat can add harshness or grit, while opening it can increase volume and improve timbre. Lips and teeth affect not only the character (what phonics you make) but also how the vibration of your vocal chords is translated into the air around you. As you become more controlled and proficient in using your voice, try to expand your musical vocabulary by learning about the basics of music and singing.  Vocal warm-ups, scales, intervals, and timbre are all helpful things to familiarize yourself with but remember the first rule of rock: do it your way. Choose your style of rock. Abandon musical lyricism, tone, and articulation. Rock singing should be rather ambiguous in rhythm, lyrics, and pitch. That is the essence of hard rock. Don't try to learn from a cd or machine. Get a great teacher. Many professional rock singers have done so. A voice coach will help you develop your voice and can give you tips in how to protect your voice.  Rock has a vast array of voice styles and methods. An experienced coach can appropriately assess your improvement. A coach will help you improve your vocal range. There are no shortcuts. It takes a long time to learn to sing well. You might have natural talent, but that will take you only so far. You have to have a solid technique to have a stable career. That is why there are so many "flash in the pan" performers. They have no technique, and their voices crash and burn quickly. You do have to be able to hold enough breath to push a note loud enough for a microphone or audience to hear it.  Focusing on core exercises such as abdominal, chest, and back muscles will help you tighten your core in order to focus on your breath. Cardio exercise such as biking, jogging, jump rope, and even brisk walking can improve the amount of breath you have for holding notes and can also help a lot if you're an active singer who does a lot of jumping around or headbanging while singing. Take care of your voice. While some singers can smoke and drink and sound like rock stars, that approach might not work for you. It's important to know the limitations of your own voice because nothing is worse than running your voice ragged before your band finishes its first set. Everybody has a different vocal range, but most male singers fall into the categories of either bass, baritone or tenor, while most females have either a contralto, mezzo soprano or soprano vocal range.  Some people have ranges that extend further than these categories. Learning your vocal range is very important because you need to know your limits. Learn how to scream. Develop a screaming-yelling style to your singing voice. Most rock singers do not utilize the same technique as pop stars do: instead of smooth transitions and mild sounds, they go for the more scream-like voice, making it sound more passionate. Try yelling parts of any rock lyrics without utilizing vocal notes and then replicating that feeling while singing.
Learn how to control your voice. Study the fundamentals of rock music and singing. Get a voice coach. Exercise to strengthen your voice. Learn your vocal range.