Frequency and sound.................(Phase, Phase-shifts and harmonics)
Hello, everyone, it's @phatstudio here, and today on still under frequency and sound we will be looking at Phase, Phase-shifts and harmonics. If you missed our previous article on spectral processors you can check it out through the link at the end of this post.
Have you ever imagined having a mix that sounded “not quite right” but you really can’t put your finger on it? You might be experiencing phase cancellation, -an occurrence that can cause certain frequencies to vanish from your mix.
Sure then, let's get on with it by first defining what phases, phase-shifts, and their correlating terms are.
Phase:
This is the difference in degrees between a point in a cycle of a wave and it's origin.
We have seen that a completed cycle runs for 360 degrees, so 180 degrees will be the phase angle for half the cycle.
Phase is actually a measurement of time express in degrees and the difference between the phases of two different point is what we called the phase-shift. The phase-shift can be of two different types we can have
- Constructive interference
- Destructive interference
constructive interference:
When we add two identical waves together at zero(0) degrees phase-shift we have a constructive interference which results in double amplitude. you can also see that a sound that is louder actually build up the amplitude.
Destructive interference:
When we add two identical waves of the same frequency and the same amplitude together at 180 degrees, we have a destructive interference. here you can see that we have a complete cancellation and zero amplitude so we actually have no sound.
sometimes you often hear people ask when does this phase-shift occur when am doing a recording or how can this phase shift occur when I am doing a recording?
Well, a real simple example will be when we are recording a snare drum. there are many occasions when we chose to record the snare from both sides, as well as from the top and as from the bottom.
>N/B: When recording sound, the diaphragms in our microphones essentially replicate the action of our eardrums, vibrating in accordance with those waves. The waves’ peaks cause the mic’s diaphragm to move in one direction, while their troughs generate movement in the opposite direction.
When we are talking about sound, we have compression and refraction.The movement going up and down.
looking at the waveform and seeing from the diaphragm of each of the microphone is exactly the opposite as for the upper part of the snare drum and as for the lower part of the snare drum.
It is also important to note that this phasing will not occur at all frequencies of the snare but we will differently notice that there are some frequencies missing or even amplified.
N/B: These won't completely cancel out the whole snare, but could have destructive or constructive interference on certain frequencies and thus have an impact on the frequency content when summed together. So mic placement makes a huge difference.
For this reason, we have a 180-degree phase offset switch on the console or on the microphone pi-amp, which allows us to offset the phase by 180 degrees and inverted the signal.
we can also run into these phase problems when we double track a recording.
another trick could be to pan each of the two channels in different direction left and right. This way they are not summed when the come out of your speaker, but during mix drown were you mix down you track in mono, you will still have the problem. on certain systems when you play back the song you will miss a lot of the frequency content.
Harmonics
These are additional pitches to the fundamental that are sounded within a signal. They are higher pitched and based on fractions or ratios of the original signal.
The harmonic content of a sound can be categorized into two groups and that's are;
Fundamental frequency: This is the sine wave that determines the pitch of the sound.
Harmonics: These are sinewave that whole multiple numbers of the fundamental frequency.
If the fundamental frequency of a (concert) A2 note is 110 hertz, the harmonic will then be at 220 which is the second harmonic and exactly an octave up. we can see the example below as well.
1 x 110 Hz = 110 Hz (A2) - Fundamental frequency
2 x 110 Hz = 220 Hz (A3) - Second harmonic(octave)
3 x 110 Hz = 330 Hz (E4) - Third harmonic
4 X 110 Hz = 440 Hz (A4) - Fourth harmonic(octave)
5 x 110 Hz = 440 Hz (C#5) - Fifth harmonic
6 x 110 Hz = 440 Hz (E5) - sixth harmonic
7 x 110 Hz = 440 Hz (Unrelated) - seventh harmonic
8 x 110 Hz = 440 Hz (A5) - eight harmonic(octave)
9 x 110 Hz = 440 Hz (B5) - ninth harmonic
10 x 110 Hz = 440 Hz (C#6) - tenth harmonic
11 x 110 Hz = 440 Hz (Unrelated) - eleventh harmonic
So we can see that doubling in frequency represent an octave. seven(7) AND eleven(11) are the unrelated pitch which simply means that our ears can't relate a pitch to it.
When an audio signal travels through any type of an electronic device, we ideally want the input to be identical to the output but this is not always the case.
Every processor that our signal runs through add some harmonics that were not present on the input signal
This has to do with the nature of the electronic components. but since this added harmonic is a distortion to the input signal we refer them as Harmonic Distortion.
N/B: The harmonic distortion of a device is expressed in a percentage.
SO THESE WILL BE ALL FOR TODAY ON SPECTRAL PROCESSORS AND I HOPE YOU LEARN SOMETHING ON PHASE AND HARMONICS? I HOPE TO SEE YOU GUYS SOON.
********Also when next you hear people talk about the warm of analog sound, always remember that it is really because some harmonics are added by the devices and it's components********.
You can check out our previous article through this link
REF1.
And like always flee free to sen in your questions and suggestion through comments and I will do my best to look into it.
Thanks for reading!
