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A frequency is the number of times a repeating event occurs within a specific time frame, in our case and most often all cases, this is 1 Second.
A Frequency is a measurement of cycles per second otherwise known as Hertz (Hz). From this we can say that, 1 cycle in 1 second is equal to 1Hz
What exactly is a Cycle? Also known as a Wave, a single Cycle includes one Positive and one Negative fluctuation in pressure. Otherwise known as Amplitude.
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To understand this concept a little more let’s think of a magnet! Each Magnet has a North (Positive) or South (negative) Pole. Nature loves equilibrium, and it will always try to find balance or its “Neutral” state. It’s center, If there is no a center we can’t have Positive, nor can we have a Negative. This is because Positive and Negative are relative to Neutral or 0. You can't have +1 without 0 and you can’t have -1 without 0.
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Take a look at these speaker icons (Below), Can you see the similarities? What are the lines out in front of the speaker? You might say “Thats the sound, DUH!” and you would be exactly right. But what does that have to do with frequency? EVERYTHING.
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You might also like to think of Frequency as vibration. We can think of a slow vibration or a fast vibration. A slow vibration could also be considered a “Low” vibration, and a fast vibration could be considered “High”.
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Let’s dig a little deeper! Like to the center of your brain deep! In order to break things down a little more we need to understand our body and how we hear, and how beautiful of a mechanisms our ears truly are. Our ears are made of many little components that all work together to reproduce sounds that we hear. But how exactly do we hear and what exactly are sounds?
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We discussed earlier that a frequency is a repeating cycle of positive and negative pressures, otherwise described as amplitudes. But what exactly is the Pressure?
Example, Have you ever flown in an airplane, or driven through the mountains and your ears felt like they were full of pressure and needed to pop? How about swimming deep underwater? The deeper you go the more pressure you feel in your ears and sinuses.
This is an example of atmospheric pressure! That's right, atmosphere like the Air! Sound needs a medium to move though such are Air, Water, or solids. Some sort of molecular substance.
Our ears respond to Positive and Negative amplitudes of Air Pressure! The air pressure changing outside our ear vibrates our eardrum, which causes this itty bitty bone in our ear to hit our Cochlea. You may have heard about Cochlear implants for people who are Deaf or hard of hearing. The reason why the Cochlea is important is because its directly connected to our hearing nerves! Also, the reason you get dizzy and/or lose balance when you spin in circles, is the same reason why the cochlea is able to transmit the sound. The cocleah is actually full of fluid! That's right, Air Pressure Changing outside, causes fluid in our ear to vibrate! Crazy stuff!
Think about a Drop of water in a still pond. This is a beautiful visual representation of this vibrational phenomenon!
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So now that we know how our ear works. Let's go back and take a look at that speaker again. A Speaker works by changing the air pressure around it. In either a Positive Pressure or a Negative Pressure. The bigger the speaker, the more air it can move, the more pressure it can create.
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On a physics level, a “High Pressure Area” is an area that is compressed full of air molecules and atoms. A “Low Pressure Area” is the opposite. It’s Air molecules are thinned out and sparse. High Density vs Low Density.
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Now that we’ve covered how the ear works, and how the speaker works to change the air pressure or, amplitude. Lets get back to Frequency and what that is. We discussed that a Frequency is a measurement of repetition over time. But didnt get into what happens when we change the Rate at which that repetition happens.
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As you can see in the image (Below) on the far left we have a 1Hz frequency, on the Right we have a 3Hz frequency.
- A 1Hz frequency is defined as 1 cycle per second, using that logic we can come to the conclusion that a 3Hz frequency is 3 cycles per second.
- The More cycles per second, the higher the frequency, in other words. We see the cycle repeat more Frequently!
Now, 1Hz is completely inaudible. In fact, the human can only hear from 20Hz to 20,000Hz or 20KHz for Kilo Hertz (Kilo as in one thousand). Remember that Low numbered frequencies are slow, and high numbered frequencies are fast. The more frequent it happens the higher the frequency is.
- Putting this all together, If the speaker is vibrating at low frequency, what we hear (and more so feel) is a low pitch or tone. If the speaker is vibrating at a high frequency, what we hear is a high pitch or tone. If the cycle, or sound wave, has a low amplitude, there will be less pressure (Like a whisper), making the sound quieter. If the sound wave has a High Amplitude, this will result in more air pressure and a “Louder” sound (like a rock concert).
High Amplitude = Loud
Low Amplitude = quiet
Slow frequency = low pitch
Fast frequency = high pitch
- Understanding these fundamentals will be crucial to understanding how frequencies operate. Some more examples of how amplitude and frequency are independent of each other.
A sound wave can be a low amplitude with a high frequency.
A sound wave can be a high amplitude with a low frequency.
A sound wave can be a high frequency, high amplitude.
A sound wave can be a low frequency with a low amplitude.
- These are the ways we express loudness/ volume, and pitch/ tone.
- So what are Frequencies? Depending on your medium, Frequencies are Tones and/or vibrations that are measured in cycles per second otherwise known as, Hertz (Hz). They can be both loud or quiet, as well as Low Pitch or High Pitch.
- In a musical aspect we would call these Notes, and different combinations of frequencies Chords. But more on that later.
What Are Frequencies? Hz - The Basics of Sound & Human Hearing
What Are Frequencies? Hz - The Basics of Sound & Human Hearing