Do let us know if we are wrong, but we believe you here because you can´t read standard notation and you would rather play by ear after reading the tabs. If you want to become an expert at playing by ear, you will need to fully know the major scale that comprises of seven different chords. Of course, it is not going to be easy scrutinizing all genres of music with the aforementioned formula, but you need not require a particular set of skills to locate the key of a song on the guitar. What you need is a just a little bit of reference and you are good to go.
Step 1: Pay undivided attention to the song
The first step you need to undertake to find the key of a particular song is to listen to the song closely. We would recommend you to place your guitar elsewhere or it could affect your concentration. And, while listening to the song, you should focus in on the tonal center of the song. You should identify the sections where the song lands, and pay close attention to that particular note.
Step 2. You should sing to recognize the tonal center
After identifying the note, you should sing along to the note; the note must sound like the right fit throughout the song, from the start to the finish. Doing this will allow you to connect the pathways in your head, allowing you to identify the notes.
Step 3. Use your guitar
Now, you should proceed to find the note you have in your head, on the guitar. If you can´t recall the note, you should start from scratch again. But, if you´ve got it, you should identify if the note you are playing on the guitar goes well with the note you´re singing. If the notes match, the key of the song should probably be in that particular note.
Step 4. Deciding if it is in major or minor
You can then play a major chord first and identify if it goes well with the song. If it doesn´t, you can try your luck with the minor chord. You should be able to recognize the chord that sounds best with the song and the key of the song will be in that particular chord.
Step 5. Verification of the key
You should then proceed to verify the key of the song. You should know that the first chord of a song isn’t always the key. The key of a song could be any of the chords in the song. Therefore, it is necessary for you to write down all the chords in the song. For easier purposes, you can search for the chord chart of the song. While identifying the key, it is of paramount importance for you to be well-versed in your major keys. In order to verify the key, there is a requirement for you to be skilled and educated on all the chords that transpire diatonically in the key of a particular major chord.
Things You Should Know
Relative Minor Keys
You should be on the lookout for relative minor keys. All major keys boast of a relative minor key that sounds exactly the same, owing to similar chords and notes. Therefore, you may be led into believing the key of the song is a major key, when all the while, it may be a relative minor key.
Non-diatonic chords such as the major 2 chord and major 7 chord can throw you off as they don’t transpire naturally in the key. If these chords are in a song, you can have difficulties identifying the key of the song. Hence, during such times, it is necessary for you to pay close attention to the tonal center of the song. You should identify the sections where the song lands and pay close attention to that particular note.
You should also be on the lookout for key modulations—the process where there is a change of key in the song.