Compressions are a parts of a sound wave where the particles of the medium through which the sound travels are squeezed together. Rarefactions are a parts of the sound wave where the particles of the medium through which the sound travels are stretched apart. The sound wave travels in all directions. The skin of a drum is a thin sheet of plastic or animal skin stretched tightly across a frame.
It vibrates when struck with drumsticks. The vibration shakes the air nearby and spreads out as sound waves. These cues are: 1 which ear the sound hits first known as interaural time differences , and 2 how loud the sound is when it reaches each ear known as interaural intensity differences.
If a dog were to bark on the right side of your body, you would have no problem turning and looking in that direction. This is because the sound waves produced by the barking hit your right ear before hitting your left ear, resulting in the sound being louder in your right ear. Why is it that the sound is louder in your right ear when the sound comes from the right?
Because, like objects in your house that block or absorb the sound of someone calling you, your own head is a solid object that blocks sound waves traveling toward you.
When sound comes from the right side, your head will block some of the sound waves before they hit your left ear. This results in the sound being perceived as louder from the right, thereby signaling that that is where the sound came from.
You can explore this through a fun activity. Close your eyes and ask a parent or friend to jingle a set of keys somewhere around your head. Do this several times, and each time, try to point to the location of keys, then open your eyes and see how accurate you were. Chances are, this is easy for you. Now cover up one ear and try it again.
With only one ear available, you may find that the task is harder, or that you are less precise in pointing to the right location. This is because you have muffled one of your ears, and therefore weakened your ability to use signals about the timing or intensity of the sounds reaching each ear. When audio engineers create three-dimensional audio 3D audio , they must take into consideration all the cues that help us locate sound, and they must use these cues to trick us into perceiving sound as coming from a particular location.
Even though with 3D audio there are a limited number of physical sound sources transmitting via headphones and speakers for example, only two with headphones , the audio can seem like it is coming from many more locations.
For example, if an audio engineer wants to create a sound that seems like it is coming from in front of you and slightly to the right, the engineer will carefully design the sound to first start playing in the right headphone and to be slightly louder in this headphone compared with the left.
Video games and movies become more immersive and life-like when paired with these tricks of 3D audio. When watching a movie, for example, sets of speakers within the movie theater can focus the sound direction to allow for a match between what you are seeing and what you are hearing. For example, imagine that you are watching a movie and an actress is having a phone conversation on the right side of the screen.
Her speech begins to play mostly through the right speakers, but as she moves on the screen from right to left, the sound follows her gradually and smoothly. This effect is the result of numerous speakers working in tight synchrony, to make the 3D audio effect possible. Virtual reality VR takes this immersive experience to a higher level by changing the direction of the sound based on where you are looking or are positioned in virtual space.
In VR, by definition, you are virtually placed in a scene, and both the visual and auditory experiences should mirror your experience of the real world.
In a successful VR simulation, the direction of your head movements and where you are looking determine where you perceive the audio as originating from. Look directly at a space ship and the sound of its engines come from straight ahead of you, but turn to the left and now the sound comes at you from the right.
Move behind a big object and now the virtual sound waves hit the object directly and hit you indirectly, dampening the sound and making it more seem muffled and quieter. Research scientists and professionals in the film and video game industry have used simulated sounds to learn more about hearing, and to enhance our entertainment experiences. Some scientists focus on how the brain processes sounds, while others analyze the physical properties of sound waves themselves, such as how they bounce or are otherwise disrupted.
Current timeTotal duration Google Classroom Facebook Twitter. Video transcript - Check out this speaker. If we plug it in, it makes sound. Scientists often use the word oscillation to refer to the back and forth motion of an object. This speaker is oscillating too fast for the human eye to see, but if I put a piece of paper on the speaker, we see that because the diaphragm is oscillating, it's bumping into this piece of paper and causing it to dance.
The oscillation of the diaphragm will also cause the air in front of the diaphragm to move back and forth, but here's the interesting thing.
The air in front of the diaphragm doesn't actually travel away from the speaker. The air molecules in front of the speaker just oscillate back and forth. So, how can you hear the sound from a speaker if the air next to the speaker doesn't actually make it to your ear? Well, the reason is that the oscillating air in front of the speaker causes the air in front of it to also oscillate. This causes the air in front of that air to start oscillating, which causes the air in front of it to start to oscillate, until finally, the air that's actually next to your ear and your eardrum starts to oscillate back and forth.
0コメント