“The thyroid is a butterfly-shaped gland that sits low on the front of the neck. It is associated with voice quality. Thyroid hormones act throughout the body, influencing metabolism, growth and development, and body temperature. During infancy and childhood, adequate thyroid hormone is crucial for brain development.” -W

To improve singing there are some exercises that you can do:

• Proper deep breathing is key.
• Excercise because it opens up the lungs and stretches the diaphragm. For example, hiking.
• Lip flutters. Babies do this a lot, really cute.
• Drinking plenty of water and chamomile tea.
• Breathing exercise: Alternate nostril breathing. Plug one nostril with your finger; Inhale through the left and exhale through the right, then inhale through the right, and exhale though the left, and so on. 
• Inhale for 5 seconds, hold breath for 5 seconds, exhale for 5 seconds, hold breath for 5 seconds, inhale for 5 seconds, and so on. Keep breath steady and calm. Don’t manipulate or force. Go with the flow. Be kind to yourself.