Tuning the D-String to the A tuning fork
Before appreciating the nature of guitar tone and harmonics, it may seem a little odd to tune the D string to an A tuning fork. The reason we want to tune the D string as the starting point is that it is generally more stable than the A string, and it is closer to the centre of the compass of the open strings.
Not only that, but we can easily tune it using an A 440 Hz tuning fork, which is the standard fork. It's not a question of judging the correct intonation of the perfect 12th between the pitch of the open string and of the pitch of the tuning fork. This tuning is also done by listening to beats.
When listening to beating between the fork and the D string, we need to listen at the pitch of the fork, despite that we are playing a string of a different note. So we're listening to an A pitch even though we are playing the D string.
This works because the third harmonic of the D string is an A at the same pitch as the fork. You can hear the pitch of the harmonic by plucking it over the 7th fret. Remember, that harmonic is still present in the sound of the ordinarily plucked open string.
When tuning the string to the fork, focus on this pitch, and you should have no trouble hearing the beating. In tuning the D string to the A fork, we are aiming to eliminate the beating.
In this example, the D string is being tuned up to the fork. As soon as you hear the fork strike, keep your ear focussed on that pitch, and you'll hear the beating being reduced, as the string is tuned up.
Not only that, but we can easily tune it using an A 440 Hz tuning fork, which is the standard fork. It's not a question of judging the correct intonation of the perfect 12th between the pitch of the open string and of the pitch of the tuning fork. This tuning is also done by listening to beats.
When listening to beating between the fork and the D string, we need to listen at the pitch of the fork, despite that we are playing a string of a different note. So we're listening to an A pitch even though we are playing the D string.
This works because the third harmonic of the D string is an A at the same pitch as the fork. You can hear the pitch of the harmonic by plucking it over the 7th fret. Remember, that harmonic is still present in the sound of the ordinarily plucked open string.
When tuning the string to the fork, focus on this pitch, and you should have no trouble hearing the beating. In tuning the D string to the A fork, we are aiming to eliminate the beating.
In this example, the D string is being tuned up to the fork. As soon as you hear the fork strike, keep your ear focussed on that pitch, and you'll hear the beating being reduced, as the string is tuned up.