The basis of quantitative measurement of tinnitus relies on the brain’s tendency to select out only the loudest sounds heard. Based on this tendency, the amplitude of a patient’s tinnitus can be measured by playing sample sounds of known amplitude and asking the patient which he or she hears. The tinnitus will always be equal to or less than sample noises heard by the patient. This method works very well to gauge objective tinnitus (see above.) For example: if a patient has a pulsatile paraganglioma in his ear, he will not be able to hear the blood flow through the tumor when the sample noise is 5 decibels louder than the noise produced by the blood. As sound amplitude is gradually decreased, the tinnitus will become audible, and the level at which it does so provides an estimate of the amplitude of the objective tinnitus.