Most common cause of singers nodule is
Infection
Vocal abuse
Allergy
Carcinoma
Vocal nodules( Singer's nodules) They appear symmetrically on the free edge of vocal cord, at the junction of anterior one - third, with the posterior two - thirds, as this is the area of maximum vibration of the cord and this subject to maximum trauma. They are the result of vocal trauma when a person speaks in unnatural low tones for prolonged periods or at high intensities. Ref: Textbook of diseases of ENT, PL Dhingra, 7th edition, pg no. 343
Larynx