Audiology and hearing health professionals in developed and developing countries (2002), Lyn et al. (1998), and Swart et al. (1995), impacted cerumen is one of the most common ear diseases and causes of hearing loss, with prevalence rate between 7.4% and 63%. Additionally, otoscopy does not require a great deal of expertise beyond basic training and is useful to refer a child when the tympanic membrane cannot be visualized due to occlusion of the external auditory meatus by cerumen. Pure-tone audiometry screening, in which there is typically no attempt to find threshold, has been found to accurately assess hearing status in children six years and older, when trained health workers
Substance theory substance theory is the argument from conception. The argument claims that in order to conceive of an object's properties, like the redness of an apple, one must conceive of the object that has those properties. According to the argument, one cannot conceive of redness, or any other property, distinct from the substance that has that property. The idea of substance was famously critiqued by David Hume, who held that since substance cannot be perceived, it should not be assumed to exist. But the claim that substance cannot be perceived is neither clear nor obvious, and neither is the implication obvious.