I have a question about PITCH

Ayush

How do you know if someone or ourselves singing on pitch or not? When singing a scale I know if you hit the right note, yeah you're on pitch but I have problem understanding it on singing a song. I used to think maybe it's about the original melody of the song(where you sing the melody exactly same as recording you are on pitch) but I have seen many videos of Ken reacts where even though the singer changed the melody completely. Ken still says he/she was spot on.
I'm finding it hard to get a grasp of this concept.

Wigs

You should research a bit about song keys. The melody of a song is a bunch of notes that are found in the songs "key". For example if a song is in the key of a C major scale (which are all the white keys on a piano), you can sing a completely different melody but as long as the notes you sing are white keys it will sound in pitch.

Ayush

I know about keys I'm a guitar player. There are so many scales a song can be in plus if the song keep changing chords and key there is no way to know all the notes correctly. And I don't think someone can know the exact note they wanna sing(in case of improvisation) unless they are born with Perfect Pitch which is less than 1%.

Vocality

@Ayush

To my knowledge singers use relative pitch, sure some singers have perfect pitch not many and the ability to sing in a melody usually starts from breaking down a song line at a time and practice which takes time to learn especially if it's hard song. You can find singing melodies on midi or music score files. Muscle memory from training scales helps us to get the right notes and best way to check if were singing on pitch is listen back to our recordings. I also use a pitch app called sing scope find this useful checking pitch and other issues.

My pitch wasn't great at the start but with regular practice, ear training, as a result improved alot and i can now learn melodies quicker.

Wigs

Diving deeper you can sing notes that are found in each chord the same way you can find harmonies. For me it's an inate thing if I hear a note that's out of place it jars my ears. I can't harmonize but can sometimes adlib but I've no idea what the notes are I'm singing, sometimes it takes a few goes to find something that fits but when it does I just know because it sounds right.

kenmack

To answer your question, you'll know if you are on or off pitch when you can hear it (or when some else who can hear it tells you). Hitting the note with the right interval sounds good while missing the note with an improper interval sounds bad. Hopefully, your ear is good enough to discern. I can tell most times when I don't quite hit a note cleanly. It is even easier for me to discern when someone else is off pitch. I am also better at detecting flat than I am sharp. The way Western music scales are structured, with their half and whole steps, is pleasing to our ears. When you miss the note, it is not so pleasing. I notice this more easily now since my children took up band and have thus exposed me to much more live music. Hopefully my ear has not deluded me and that my perceptions are true. A key change does not change whether or not the melody will be melodic to the ear once the key change is made. You'd hopefully go right back to being on pitch in the new key. In fact, the discord of a key change is often the affect that the song writer sought. In a sense, the step between keys is "off pitch" (except maybe with relative majors and minors). I understand what you seem to mean when you described what I took to be getting all mixed up in your head when moving through keys especially if done several times in one song. I've not experienced that challenge so I've nothing to give regarding that. I hope I helped some. I'm not a trained musician, but that is theory as I currently understand it.