Sounds can easily be localized in space. This is because there are binaural and monaural cues to sound localization. Binaural cues require two ears. Monaural cues refer to the way the auricle can detect sounds that are coming from above, below, in front or behind the person. Binaural cues depend on differences in the way sounds are detected by the two tympanic membranes. Sounds from each ear are heard at slightly different times and at different intensities so as to be able to localize sound. Hearing loss or deafness can be congenital, in which the person has it from birth, or conductive, which usually happens because of noise exposure, age, or exposure to certain toxins or diseases, such as measles or mumps. Hearing aids can help this. With sensorineural hearing loss, the problem is within the signaling of nerve cells from the inner ear to the brain. The only treatment for this is cochlear implants, which stimulate the auditory nerve.
OTHER SENSES There are two chemical senses. These are taste or gustation and smell or olfaction. These senses work together in order to describe the properties of the food a person eats. There are probably six different basic tastes. These include the categories of salty, sour, bitter, and sweet, as well as the taste called umami, which detects the amount of monosodium glutamate in food. The taste sensation of fatty is also suggested as a probable separate taste category. The taste of something is detected by taste buds, which stick out from the surface of the tongue. These taste buds detect chemical changes in the saliva and transport the information to the brain through different cranial nerves. The parts of the brain associated with taste are the thalamus, the limbic system, and the medulla. There is also a gustatory cortex found between the temporal and frontal lobe. Figure 17 shows the anatomy of these taste buds:
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