What is Phase | Polarity - How Frequencies Interact With Each Other
- If you remember from the First lesson (what are frequencies) that a frequency is made up of 1 positive amplitude, and 1 negative amplitude. Depending on the number of cycles per second or Hz, will determine the tone or pitch of our frequency.
- In order to understand Phase, we’ll need to address Polarity first. Let’s take a look at a single cycle of a wave. We have 1 positive amplitude and 1 negative amplitude. The positive amplitude of the cycle has a positive Polarity. While the negative amplitude has a negative Polarity. This should seem fairly straightforward because it is!
- If the amplitude is positive, so is the polarity. If the amplitude is negative, so is the polarity!
- So now that we understand Polarity, let's take a look at Phase and how it's related to Polarity. While Polarity indicates whether the amplitude is Positive or negative. Phase is represented by Degrees, and indicates the exact point of time within a cycle. If we were to cut a wave cycle in half, and place the Negative polarity directly under the positive polarity, we’ll get a full circle! A Full circle is 360 Degrees around. This is very important to understand because this is the entire concept of measuring Phase.
- If we start at 0 Degrees and move towards the peak of our positive polarity. The moment we get to the top we’ll be at 90 degrees.
From the peak of the positive polarity back down to center, we will have completed 180 degrees as we’ve traveled half a circle.
Traveling further to the Peak of the negative Polarity, we will have traveled another 90 degrees but in the opposite direction, This would be 270 from the start.
From the peak of the negative polarity back to center would be another 90, thus completing the full 360 degrees of the cycle.
- In order to truly look at Phase, we need to look at two waves at one time. In our lessons prior, we've only focused on a single frequency. Phase is the comparison of two waves and whether or not they are aligned.
- If wave 1(black) is in its positive Polarity, and wave 2 (red) is also in a positive Polarity, these two waves would be considered “in phase”.
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If wave 1(black) is in its positive Polarity, and wave 2 (red) is in its negative Polarity. These two waves would be considered “out of phase”.
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Let's keep the numbers simple for now and we'll get into some demonstrations later (see youtube video for auditory examples).
If a wave’s positive polarity is equal to +1,
and its negative polarity is equal to -1.
What happens when we add those together? -1+1=0 or 1+ -1=0.
If we have a positive Polarity, 1. And we introduce a second wave with a negative Polarity, -1. They cancel each other out.
Resulting in, well, nothing!
This is the fundamental principle of phase and polarity. Phase is the correlation of 2 waves within their respective cycles. While polarity is the state a single wave is in and whether it's positive, negative, or neutral.
- So what happens if we have two waves that are both in phase? This is called constructive interference or superposition. It can be calculated as 1+1=2. just as -1+-1=-2. Having two waves that are in phase will result in the summing of the two waves resulting in a greater amplitude. Regardless of whether they Are both positive or negative. It’s simple addition.
- If we have two waves that are out of phase, this will result in what is called destructive interference. Having -1+1 will equal 0. Meaning the result of the two waves is nullified because of destructive interference otherwise known as ‘phase cancelation’.
- Using arbitrary numbers. If wave #1 has a positive amplitude of 10, and wave #2 has a positive amplitude of 5. The superposition of these two waves will be an accumulative amplitude of 15. Because both of the waves were in phase and positive.
- Using arbitrary numbers. If wave #1 has an amplitude of 10, and wave #2 has an amplitude of -5. The result would be destructive interference that will reduce the summed amplitude to +5 because wave #2 was out of phase with wave #1.
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Using arbitrary numbers. If wave #1 has an amplitude of 10, and wave #2 has an amplitude of -10. The result would be perfect phase cancellation. Meaning that wave #2 completely canceled out wave #1 because
A. Their polarities were opposite of each other
B. Their amplitudes were exactly opposite or 180 degrees.
- Understanding this is crucial to predicting the results of mixing multiple waves together. If they are identical frequencies perfectly 180 degrees out of phase, you will hear absolutely nothing! If the frequencies are identical and are perfectly phase aligned, the result would be the summing of amplitudes. Meaning the overall Volume will get louder.
- When explaining this principle, I like to keep it simple with 1+1=2 and -1+1=0. But in reality, there is an infinite difference between 2 waves in nature. Think of someone whistling at a rock concert. Even if the person is whistling the exact frequencies, the amplitude of the whistling could never be loud enough to affect the amplitude of the rock concert.
- Polarity defines whether the amplitude of a wave is positive or negative.
- Phase is both:
A measurement of where a wave is within its cycle using 0-360 degrees.
A method of comparing 2 waves within their own respective cycles and to what degree they are aligned with one another.
- If both waves are in superposition, meaning both of their positive and negative polarities are aligned, they are considered in phase. The amplitudes of the waves are summed together to create a louder sound. This is also called constructive interference.
- If the first wave is in its positive polarity, and the second wave is in its negative polarity at the same time. These are considered 180 degrees out of phase. In other words, they are undergoing phase cancellation thus producing No sound.