That Sounds Delicious!

Imagine you are hosting a slumber party at your house! As you are preparing the food, you can hear the popcorn popping in the microwave while patiently waiting for that "ding" in the oven which signals that the brownies are ready. At the same time, there are those bursts  and sizzles as you deep-fry the pancake-battered Oreos. Then, there are those other sounds, like the music playing in the living room, which made you set your phone from silent to ringing! You need to hear it because the texts of your friends will let you know if they're already near.

There are just too many sounds  in our environment! Just think about the slumber party scenario. In fact, even the simple act of eating can be included. Can you hear crunchy sound of the chicken skin as you bite? Or the clanking sounds of your utensils against the plate? Imagine the sound created when one is opening the 1.5 bottle of Coca-Cola. Add to that the sound of a person "Hmmm" savoring his favorite dish. Sounds! Sounds everywhere!

 Does it make you wonder how the brain processes these stimuli? I mean, isn't it amazing that when you hear your phone ringing, you could find it by listening to your ringtone? Or isn't it great that we can identify various sounds, like your friend saying "Delicious" after taking a bite of your specialty, brownies? 

Well, so that we can be enlightened with these awesome phenomena, let me explain briefly some of our brain's ways for doing these. Research shows that there are two streams for processing sounds. We have the "what" stream and the "where" stream. The "what" stream deals with the identification of sounds.  Then, for the "where stream, it is responsible for locating sounds. 

But where do these streams pass? To fully understand its paths, let me first describe you important structures in processing sounds. Let us go straight ahead to the auditory areas in the cortex. One of them is called core area which includes the primary auditory cortex and some nearby areas. These are found in the temporal lobe, the lower sides of the brain. This core area can be activated by simple sounds. Another area is called the belt area and the parabelt area. These areas, which surround the core area, deal with more complex stimuli. With this being said, you can comprehend that one of the properties of the auditory areas mentioned is hierarchical processing - signals are first processed in the core area and then travel to the belt and parabelt areas. Simple stimuli at the core and complex stimuli extend to the outside of the core.

Alright! Now that we have identified some important  areas in the auditory processing, we can proceed with the tracing of the "what" and "where" streams. The "what" stream starts at the front of the core and belt, and extends to the prefrontal cortex. It is also called the ventral stream because it is located in the front areas. Then, for the "where" stream, it starts at the back of the core and the belt. Afterwards, it extends to the parietal cortex and then to the prefrontal cortex. It is also called the dorsal stream for it is located at the back. You may ask, where did we get these information? Evidences were from brain-imaging techniques, human brain-damaged patients and neural firing in the areas.

Well, I hope this set of facts did not overwhelm you. So, as for a conclusion, just take this scenario.

When you hear the "beep" of your phone, and you have identified it, that is the "what" stream at work. But when you try to locate it using by the "beep" sound, that's the "where" stream at work!

===TRAZO GAEA ISABEL D.===

References

Goldstein, E.B. (2010). Sensation and perception (8th ed). Belmont, CA: Cengage Learning. 

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