New York: Poor lung functioning is likely the reason behind voice fatigue, finds a new study aiming to investigate underlying risk factors for voice problems and gender differences in speech. Vocal fatigue -- hoarseness, vocal tiredness, muscle pain and lost or cracked notes -- is a common complaint among teachers and one of the most debilitating conditions that can lead to vocal damage. The findings showed that females face a significantly higher risk than men of developing long-term vocal problems. "The study is the first to connect voice fatigue problems with gender-based physiological differences in lung functions, pointing to respiratory function as a source of the gender inequality in voice problems," said lead researcher Eric Hunter from the Michigan State University in the US. The lung function of women in the amount of air they inhale and exhale was linked to getting voice fatigue. Also, the higher incidence of prolonged problems among women has been associated with a number of gender differences including physiological differences in the laryngeal system, differences in the endocrine system, and differences in pulmonary usage. For the study, the team analysed 122 elementary and middle school faculty members (96 females, 26 males). The teachers' scores of vocal fatigue index -- a standardised survey tool that can help identify individuals with vocal fatigue -- were matched with the results of spirometry measures -- a medical tool often used in vocal health clinics to measure how much air one inhales, and how much and how quickly one exhales. The results showed that women weren't able to inhale and exhale as much air as men. The study supports the use of spirometers to be used as a vocal fatigue-screening device for teachers. It can be a simple and low-cost tool that could aid caregivers in vocal health clinics in tailoring therapies for patients with low spirometer measures, the researchers noted. The findings were presented at the 171th Meeting of the Acoustical Society of America (ASA), held recently in Utah in the US.