Sound is measured in decibels (dB). We can hear sounds ranging from a low rumble up to a high-pitched whistle. The lowest sounds can sometimes be felt in the chest, while very shrill sounds may be so high that we cannot actually hear them.
A bat’s squeak is at the limit of what human beings can hear, and many people cannot hear this noise at all. Our hearing is not very sensitive compared to animals such as dogs, who can hear very high-pitched sounds. Dogs are able to respond to a supersonic whistle that cannot be heard by humans at all.
As for our tongue:
There are distinct regions on the tongue where the main tastes are recognized. The tongue is covered with small bumps, called taste buds that are grouped together in areas with different functions. These taste bud react to simple tastes and pass messages to the brain.
Taste buds on the tip of the tongue detect sweet tastes, and those at the back of the tongue detect bitter tastes. Groups of taste buds at the side of the tongue measure sour and salty tastes. The taste of any food is a combination of these four basic tastes.
These taste buds, or ‘flavor receptors’, transmit the different taste information as a message to the brain. It is the brain which processes the information and tells us what food is actually in our mouths.
We each have around 10,000 taste buds on our tongues. As we grow older our buds become less sensitive. This is one of the reasons why elderly people may no longer enjoy their food so much.
Hot foods taste better because the heat causes more of the pleasant smells to rise into the nose. These abundant smells contribute to the total taste of the food.
When we taste food it is a mixture of both taste and smell. As you eat, tiny food particles drift up into the passage of the nose from the back of the mouth.
The smell of the food contributes to the simple tastes detected by the tongue. This explains why food tastes odd when we have a cold because the nasal organs become inflamed and therefore the sense of smell is temporarily smothered.
When we eat spicy foods, such as curry or chili, mild pain also forms a part of the characteristic taste. If these foods did not burn the mouth slightly, they would not taste like curry or chili at all.
If we were to lose our sense of smell, almost all taste sensation would be lost as well, meaning that we would not enjoy the taste of our food nearly so much.