Musical hallucinations are also relatively common in terms of complex auditory hallucinations and may be the result of a wide range of causes ranging from hearing-loss (such as in musical ear syndrome, the auditory version of Charles Bonnet syndrome), lateral temporal lobe epilepsy, arteriovenous malformation, stroke, lesion, abscess, or tumor.The Hearing Voices Movement is a support and advocacy group for people who hallucinate voices, but do not otherwise show signs of mental illness or impairment. High caffeine consumption has been linked to an increase in likelihood of one experiencing auditory hallucinations. A study conducted by the La Trobe University School of Psychological Sciences revealed that as few as five cups of coffee a day (approximately 500 mg of caffeine) could trigger the phenomenon. Visual
A visual hallucination is "the perception of an external visual stimulus where none exists". A separate but related phenomenon is a visual illusion, which is a distortion of a real external stimulus. Visual hallucinations are classified as simple or complex:

Simple visual hallucinations (SVH) are also referred to as non-formed visual hallucinations and elementary visual hallucinations. These terms refer to lights, colors, geometric shapes, and indiscrete objects. These can be further subdivided into phosphenes which are SVH without structure, and photopsias which are SVH with geometric structures. Complex visual hallucinations (CVH) are also referred to as formed visual hallucinations. CVHs are clear, lifelike images or scenes such as people, animals, objects, places, etc.For example, one may report hallucinating a giraffe.
Since richer nations would have lower levels of absolute poverty, relative poverty is considered the "most useful measure for ascertaining poverty rates in wealthy developed nations" and is the "most prominent and most-quoted of the EU social inclusion indicators".Usually, relative poverty is measured as the percentage of the population with income less than some fixed proportion of median income. This is a calculation of the percentage of people whose family household income falls below the Poverty Line. The main poverty line used in the OECD and the European Union is based on "economic distance", a level of income set at 60% of the median household income. The United States federal government typically regulates this line to three times the cost of an adequate meal.There are several other different income inequality metrics, for example, the Gini coefficient or the Theil Index. Other aspects
Rather than income, poverty is also measured through individual basic needs at a time. Life expectancy has greatly increased in the developing world since World War II and is starting to close the gap to the developed world. Child mortality has decreased in every developing region of the world. The proportion of the worlds population living in countries where the daily per-capita supply of food energy is less than 9,200 kilojoules (2,200 kilocalories) decreased from 56% in the mid-1960s to below 10% by the 1990s. Similar trends can be observed for literacy, access to clean water and electricity and basic consumer items.