What techniques do singers use in order to hear if they sing the correct pitch? I do not want opinions. What is really going on? What is it that good singers actually do that bad singers don't? What is the things that the great singets do? I have taken singing lessons without getting an answer to this question.
Many kinds of musicians, including singers, have to adjust intonation (how well they are hitting the notes) in real time. The way they tell whether they are in tune or not is by ear. Until a musician or singer has highly developed their pitch sense, they pretty much have to have other instruments playing or singer singing to hear if they are in tune with the rest of the ensemble. Normally singers practice with a piano or some accompaniment while they are learning to intonate and developing their pitch sense.
When more than one pitch is played or sung at the same time, they create interference (in the scientific sense of the word) between them. The interference can be heard, and in fact the sound of the interference between different notes is a big part of what makes polyphonic music interesting to us. When the notes have the proper frequency ratios between them, the additional notes created by the interference sound pleasing to us. When the frequencies of the notes are not properly spaced, the interference sounds much less pleasing. Singers learn to hear the interference notes and adjust their singing so the interference notes sound best.
The common term for what I have called "interference notes" is "beat frequencies". The easiest way to hear beat frequencies is to play two notes of the same pitch and then slightly detune one of them. If you have a piano or keyboard (perhaps ideally a synth that can play sustaining notes), you can try this yourself. Play a note on the keyboard and hold it, and then sing the same note. As you adjust the pitch that you are singing slightly, you should hear a "wow-wow-wow-wow" sound. As your voice sings closer to the exact same note, the "wow" sounds slow down until you can't hear them - that means you are on pitch. As you stray farther from the pitch, the "wow" sounds get faster and faster. Once they get fast enough, they make a new note that is created from the interference between your voice and the keyboard.
That means that singing along with an existing melody is the easiest way to work on your intonation, because all you need to do is make the "wow" sounds or beat frequencies as slow as possible. When you are singing in harmony without guide notes, you have to make the new notes created by the interference sound good without having the "wow" sound to guide you, and that takes a lot of practice.
I suggest a web search of "beat frequencies" for more information. A youtube video demonstrating how they sound might be very edifying.
In order to understand what is in tune and out of tune when you sing, you have to experience it by experimenting it in order to know what is right and what is wrong.
Before you develop your inner ear and learn to trust it, you have to start out by play one note at a time then hear it in your mind and then you sing it. After you sing, check with the tuner that how close you are to the target note. Consequently, you will learn by this process to trust your inner ear.
In terms of bad singers, they cannot tell whether they are in tune or not. The factors can be:
- They don’t intentionally listen to the target notes
- Even they can hear the target notes correctly, they are unable to reproduce the sound they hear. (Lack of voice training)
- They are really a tone deaf person. (Which is quite rare, because most people will be categorized into factor 1 and 2 for the most).
However, when you start to practice you might miss target notes, but do not be discouraged just keep practicing and you will get it eventually. Just keep in mind a good musician know when he/she plays the wrong notes and correct them but the bad one has no idea at all whether he/she play them right or wrong.