As the muscles of our limbs gain strength and firmness by moderate use of dumb-bells, and other athletic exercises, so by gently and daily training the nerves and muscles connected with the vocal organs, which gain strength and tone by such judicious practice, the voice will improve in compass, fulness, roundness, sweetness, clearness, evenness, steadiness, firmness, and flexibility, whilst on the contrary violent exertion occasions an unusual rush of blood to the organs, which tends to inflame the throat, to stretch and swell the vessels beyond their healthy diameter at the risk of destroying the voice or of rendering it harsh, squeaking, thin, feeble, uneven, husky, broken, and every respect discordant.

Nathan, Isaac. Misurgia vocalis. British Library, 1836.