Here’s how to find the frequency of a sound fully automatically. But for the diehards among us, also calculate frequencies manually. Watch until the end because this is gonna be very interesting.
What are sound waves?
Sounds are vibrations in the air from pressure differences. And no, I’m not talking about that kind of air pressure. When our ears sense air vibrations, they send signals to our minds. On their turn, our minds interpret these signals as auditory information.
How to detect frequency of sound?
But how does our mind differentiate sounds? In other words, how does it know the difference between let’s say a burb and a fart?
To do that, our bodies have a few tricks up their sleeves. Among many things, they can sense the amount of air pressure, the difference in timing between both ears, and the frequency distribution of a sound. In technical terms, you may have heard of these phenomena as amplitude, phase, pitch, and so forth.
What is pitch of sound?
But for today, let’s talk pitch. Pitch is basically another word for frequency. So how do our ears know the frequency of a sound and how can you find it?
Detecting the frequency of a sound is really easy. All you have to do is look at the vibration speed. A slow vibration results in a low-pitched sound. And a fast vibration results in a high-pitched sound.
The unit of frequency: Hertz
Now, to measure the vibration speed, we use the unit “Hertz”. The human ears can hear sounds somewhere between 20 to 20,000 Hz. Where 20 Hz means 20 vibrations per second, and 20,000 Hz means 20,000 vibrations per second.
I don’t know if I have female viewers, but if those speeds don’t lead to climax, I don’t know what does.
How to find frequency of sound?
Anyhow, if you want to find the frequency of a sound, you simply have to measure the number of Hertz. This is extremely easy if you have a sine wave, which only contains one frequency.
Now, let’s find the frequency of this sound automatically. You can just drag and drop your sample onto the playlist in FL Studio. But if you need good samples, just download my free EDM sample pack.
When your sample has been dropped onto the playlist, double-click on it to open the Sampler. Then, right-click on the waveform and select “Edit in audio editor”. This will open your sample in Edison.
Detect pitch regions
As usual, Edison is where the magic happens. Just right-click somewhere on the waveform, select “Regions” and click “Detect pitch regions”. Edison will now show a marker with a label. For example, the label can say: “A5”.
“A5” stands for the note of A at the 5th octave. Notes and octaves are at the foundation of music theory. But if this sounds like gibberish to you, start first with my book The Ultimate Melody Guide.
In short, certain frequencies correspond with specific notes, such as A, B, C, D, etc. So, all we have to do is look up the frequency that belongs to “A5”. This will take you one second.
Find frequency on Google
The laziest way is to open Google and type in “A5 frequency”. Google will immediately give the answer: 880 Hz. Though, I don’t know if it’s my workstation, but Edison will mismatch the pitch by one octave. So, just look up “A4 frequency” instead. And this corresponds with 440 Hz. And there’s your answer.
How to find frequency of sound manually?
Now, here’s a fun challenge; let’s calculate the frequency of a sound manually. You can in fact do it very fast. Here’s how.
Again, open your sample in Edison, right-click somewhere on the waveform, and select “View”, “Time format”, and click “Samples”. Samples are the smallest units of digital sound. We can use it to calculate the frequency very precisely. So, dust of your 1st grade math skills. Here we go.
What is a wave cycle?
Zoom into the waveform very deeply until you see one wave cycle. A wave cycle is the duration of one vibration. For a sine wave this is the point from which the wave goes up and down one time.
Then, select one wave cycle by clicking, holding and dragging. The easiest way is to start at the center line, and stop when the wave crosses the center line again at the same angle. Be very precise, else you will get the answer wrong.
How to calculate sound frequency?
After selecting one wave cycle, look in the top-right corner of Edison where it shows the number of samples. For example, it can say “100” samples. This number is crucial.
All we have to do is use this number to divide the sample rate. You can find the sample rate in the top-left corner of Edison. In most cases, that’s 44100 Hz. So, very easy math. Divide 44100 by 100 and that’s your answer: 441 Hz.
But wait, shouldn’t it be 440 Hz?
Calculate frequency problem
Yes, but this is as precise as you can get. The result can deviate ever so slightly due to the nature of digital audio and rounding numbers. But hey, you don’t need an A+ to graduate. In many cases, the exact frequency corresponds with a musical note, which is 440 Hz in our example.
Now, using sine waves with a single frequency is easy, but in the real world, sounds contain many frequencies. So then, how do you determine the frequency of such a sound?
How to find fundamental frequency of sound?
Well, I’ll tell you what not to do. You don’t have to figure out each individual frequency until you’re bored and tired. The only thing you need to find is the fundamental frequency.
Simply put: the fundamental frequency is the lowest pitch of a sound. Hence, all you have to do is find it.
The quickest way to find it is by pressing the subscribe button. Try that right now. If it doesn’t work, don’t sweat it, here’s the solution.
Find fundamental frequency automatically
As before, just use Edison to detect the pitch regions and it will automatically give you the answer. So, right-click on the waveform, select “Regions”, and click “Detect pitch regions”.
Though, many sounds vary in pitch or don’t have much tonal information. So, this method has its limits. But in general, look at the marker that closest resembles the tonal part of your sample.
For example, in most kickdrums the tonal part is in the tail. As you can see in the video, it has a marker that says “G#2”. Mind you, Edison is off by one octave, so we have to look up “G#1 frequency”. When we search it, Google finds a value of approximately 52 Hz, which is the fundamental frequency.
This is just too easy.
Find fundamental frequency manually
Again, you can calculate the frequency by yourself as we did earlier. So, zoom in until you see one wave cycle. Select that part very precisely and look at the number of samples in the top-right corner. In my case in the video, it says “867”.
Use that number to divide the sample rate that you can find in the top-left corner. If you divide a 44100 Hz sample rate by 867, you’ll get the answer: roughly 51 Hz. The closest musical note to that frequency is G#1 at 52 Hz, as we just looked up.
So, whether you do it manually or automatically, this is how quickly you can find the frequency of sound.
Fix your frequencies
To benefit from those frequencies, you can’t just throw them together. This will result in a terrible sounding mix. Hence, you have to use the right musical ratios to get a pleasing song.
I can’t stress enough that you must get this right. That’s why I highly recommend my book The Ultimate Melody Guide. It has been a best-seller on Amazon, which is amazing. So, if you don’t know music theory, click the link to start straight away.