Answer:
Based on the information provided, it is likely that Jenny has developed a form of benign vocal fold lesion, specifically a vocal nodule. Vocal nodules are benign growths that occur on both vocal folds and are caused by prolonged or excessive vocal use, such as yelling, screaming, or singing. The symptoms described such as gradual onset of hoarseness and increased effort to produce sound are commonly seen in individuals with vocal nodules. The fact that Jenny is a cheerleader and sings in the school choir, and also often raises her voice to hold her brothers attention all of which are known to cause strain on the vocal cords and can lead to the development of vocal nodules.