What does a Type B tympanogram with a normal ear canal volume suggest?

A Type B tympanogram, which is characterized by a flat response on the graph, indicates that there is limited mobility of the tympanic membrane (eardrum). When this type of tympanogram is coupled with a normal ear canal volume, it suggests that fluid is present in the middle ear, a condition most commonly referred to as middle ear effusion.

Middle ear effusion typically occurs in the context of a middle ear infection or other conditions that cause fluid buildup, such as allergies or colds. The normal volume indicates that there is no obstruction or blockage in the ear canal, which helps to differentiate this scenario from others like tympanic membrane perforation or impacted cerumen, where the volume readings would differ. Essentially, the combination of a Type B tympanogram and a normal ear canal volume presents a clear indication of underlying issues in the middle ear, reinforcing the likelihood of fluid presence or a related pathology like cholesteatoma rather than normal function or other types of obstructions.