The first thing I will talk about is what you consume, this is because what you eat or drink can affect your voice in different ways as your oesophagus and trachea are so close together:
Alcohol - Alcohol can cause "Vocal Strain", you can put you vocal cords at risk of drying out because the muscles in your throat can become restricted. Drinking Alcohol and using your voice daily can cause permanent damage to your voice, and it can also change your vocal range.
Coffee - Coffee in excessive amounts can cause discomfort, but saying this it isn't the worst effect, coffee can tighten your muscles which results in your vocal range being restricted.
Milk and Dairy Products - Milk contains lactic acid, which can create a thick layer of phlegm, this can stop you from having clean and clear sounding vocals. If your going to drink milk before a performance it is best to drink some water after in order to get rid as much phlegm as possible. Milk doesn't not damage your vocal cords, but it can effect it before a show along with other dairy products.
Acid Fruit Juices and Fizzy Drinks - Acid Fruit Juices can cause a build up of mucus, which as I've already spoken about can effect your vocals, but Fizzy Drinks or any Drinks with Aspartame can damage your vocal cords.
Food - Cheese, yogurt, ice cream (dairy products) can create phlegm. Excessive salt, oranges, lemons, grapes and pineapple are acidic and can dry out your throat. Green vegetables can create gas and a feeling of bloat. Chocolate, ketchup, tomato products, fried foods, mustard, citrus, onions, peppermint, vinegar as they are heartburn triggers. Foods that are salty or contain caffeine may dry out your mouth and make it difficult to sing. In addition, heartburn triggers are important to avoid. No singer wants their stomach acid running into their oesophagus! If this does in fact happen then you may experience inflammation in your vocal cords which will damage your voice and has the potential to lead to the loss of your voice.
Hot Food can also damage your vocal abilities, but you can heal them by, drinking a lot of water to soothe your vocal cords. Just as mentioned here earlier, water is the best lubricant for your vocal membrane and it will help you to heal fast if your vocal cords are damaged. You should drink lukewarm water to soothe your vocal cords and avoid it when it is too cold or too hot.
Things that can improve your voice for a performance are as follows:
Baking Soda and Corn Syrup Solution - This solution is especially useful if an air-conditioner has dried out your throat. It involves using baking soda as a throat gargle.
Honey and Warm Water - Honey has a soothing effect on your vocal cords. Mix a 1/2-tsp of honey in with a glass of lukewarm water before you begin your performance. If you suffer from pollen-based allergies, using a local honey has the added benefit of helping build your tolerance to local pollens. As allergens can have an affect on your voice, any chance you have to avoid them would be to your benefit. Also, remember that sugar can sometimes coat your throat and have negative effects,
so it best to use a honey labelled "all natural"as some regular store brands have added sugars.
Pure Fruit Juice - Drinking fresh, pure fruit juice, such as pineapple, grape and apple juices, help you maintain a high level of energy, and generally help your immune system. Do not drink acidic fruit juices such as orange and grapefruit any less than an hour before you're due to sing as the citric acid can cause mucus to develop in the throat.
Food - Hard candy, liquorice tea, herbal tea and water are all soothing for the throat. Chicken, almonds, fish, yellow vegetables, apples, eggs, and rice. Ginger and Ginger extracted hot drink. In the
Philippines, they call this hot, soothing drink salabat. There is a place there called Cebu wherein most people are fond of putting ginger in any kind of food and they also drink the salabat regularly. In this place, a lot of people have good singing voices.
Do you have excessive amounts of thick mucus?
Heavy mucus and preforming is a big No No. The heavy phlegm will stop the laryngeal ligaments from vibrating fast for a high frequency or a high note. Abused vocal cords = Nodules!
If you have allergies you will need a doctor to give you antihistamines as the mucus will certainly affect your health. Antihistamines dry up the heavy mucus but at the same time will dry your natural saliva which means - NO PREFORMING while on antihistamines!
Home Remedies to sooth the voice:
Don't use your voice - Talking while you have an infection in your throat otherwise known as Laryngitis can cause permanent damage to your vocal cords and promote the growth of vocal cord nodules which you definitely don't want.Use Alcohol - Other people advise against alcohol but they are wrong. Alcohol is a powerful anti-bacterial agent. Don't gulp down the alcohol. Just micro-swallow it. Use the highest proof alcohol you can get your hands on. The idea here is not to get drunk so do this once per hour. Just a tiny bit.
Use mouthwash and let just a tiny amount of mouthwash to go down your throat - You don't want to drink it but a tiny bit won't hurt you. Do this once per hour. The next day you will be amazed how much your throat has improved.
If your suffering from vomiting you need to protect your vocals and you need to because vomiting can cause irritation to the lining of the oesophagus. Vomiting forces stomach acid usually used to digest food into your voice box and that can cause burning of your vocal cords. The effects can be reduced volume when projecting or pain when projecting or speaking. Worse, it may bring about the need surgical voice repair. On the other hand, this can be avoided by through discipline. Eating the right kind of food, regular exercises, proper hydration and avoidance of stress can all help. Remember, prevention is better than cure.