A "hammer on" refers to the technique of sounding a note without actually picking the string with the pick. The sound is produced by striking the string with one of the left hand fingers. In the following example, only the D note is picked, and the third finger "hammers on" firmly to produce the sound of the E note.
The hammer on effect is indicated by the curved line, the small "H" between the two notes in question. Remember that the second note (E), is not picked; the sound is produced entirely by the second finger "hammering on" to the string.
You must be very careful with the timing of the hammer on. Both the D and E notes are eighth notes and each should have an equal time value when played (regardless of the hammer on technique).
Play riff 22 using hammer ons as indicated.
To create a different feel with the hammer on it can be played faster. Compare the following:
In this example the E note is played immediately after the D note.
If the quick hammer on is applied to the first two beats of riff 22 it is written as such: