Hi everybody.
In this video, we're going to spend just a few minutes talking about frequency, looking at the spectrum, and listening.
First, here's a definition of frequency. Frequency is the speed of a sound's oscillation. It's what we hear as pitch.
A slower vibrating sound wave will sound lower in pitch, and a rapidly vibrating sound wave will sound higher in pitch. The unit we use to describe this vibration is hertz (Hz), that means the number of cycles per second.
A 1000 Hz tone will complete one full cycle in one one-thousandth of a second, also called one millisecond. When we look at an EQ like the one in Ozone, we see that the frequencies are measured in hertz and kilohertz meaning thousands of hertz. They're represented horizontally from left to right. Look at the numbers across the top. They show the frequencies along the spectrum.
In musical terms, we can use hertz to describe the note, pitch, or fundamental frequency of an instrument. They're all identical. Orchestras usually tuned to the note A, which equates to a pitch or frequency of 440 Hz. Low E on an electric base has a fundamental frequency of 41 Hz. We also use frequency ranges to describe an instruments' tone or timbre, because in addition to the note or fundamental pitch in instrument is playing the sound of that instrument includes many harmonics.
So let's listen to four different instruments playing the same note, and look at what make them sound different. We'll use that same 440 Hz the note A.
First, let's listen to an acoustic guitar.
Noticed a strong fundamental right it 440 Hz but also the harmonics that extend above it. You may also notice that the attack of a note, when the pick hits the strings, has energy all across the spectrum.
Now listen to a distorted electric guitar playing the same note.
We still have the strong fundamental but the distortion as a totally different set of harmonics.
If we listen to a synthesizer playing a square wave, we can see a very distinct harmonic pattern.
If we switch that synthesizer to playing a pure sine wave, we see only the fundamental. There's no additional harmonic energy.
If we were to listen to all the frequencies between 20 Hz and 20 kHz at the same level, it would just sound like noise.
Let's do some listening. I'm going to play a few tones for you, all sine waves. So it's just the fundamental and no harmonics. Notice which tone sounds higher, and where you can see it on the frequency spectrum.
Here's a tone at 1 kHz.
Here's one of 100 Hz.
And one at 10 kHz.
Now we're going to listen to three different tones. Notice which tone sounds louder.
Here's a tone at 220 Hz.
Here's one at 660 Hz.
And here's one at 1.76 kHz.
Did the tone at 1.76 k sound louder to you? It might have sounded like the tones were being played at different levels, but they weren't. They're being played at exactly the same level. So why did one sound louder?
Our hearing is wired to be more sensitive to sound in mid-range frequencies then others in our range of hearing. We're especially sensitive in the range from 1 kHz to about 4 kHz. This happens to be the range related to the intelligibility of speech. This is important to keep in mind when working with equalizers, because our acute sensitivity in this mid-range area means we have to manage this part of the spectrum very carefully, often making subtle adjustments.
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