Get a really good seal with your hands across the back of the harp, then blow quite hard into the lower holes. If you sufficiently obstruct the air's usual escape route from the openings at the rear of the covers, the air is forced back out of the upper holes of the harp, sounding the high draw reeds on the way. The sound of the low blow notes and the high draw notes sounding simultaneously is quite striking:

Some harps lend themselves more readily to this technique than others, but with a bit of practice you can get most harps to do it. In fact, if you can get a good enough seal around the harp you can also make pretty much the same sound by drawing sharply in the upper holes of the harp and letting the air be sucked into the lower holes of the harp to sound the blow reeds. Not surprisingly, you can also get the upper blow reeds to sound whilst drawing hard on the lower holes or get the lower draw reeds to sound whilst blowing hard in the upper holes, like this:

The basic effect is more of a dramatic sound, rather than a sensitive musical expression, but you can gain much more control over it by selecting which notes are sounded with careful placement of your fingers over the holes of the harp. For example, by blowing the notes C E and G and allowing the upper draw notes B and D to sound, but covering holes 9 and 10, you can get a nice voicing of a Cmaj9 chord.

Slightly trickier is blocking holes 7 and 10, but keeping holes 8 and 9 open. Playing the low draw notes now gives you a sweet G6 chord.

Lots of other voicing are possible and alternate tunings give many other possibilities.

, if you play the blow note and the overblow in hole 1 of a C harp (which can often be somewhat easier than producing a clean overblow from this hole!), you get the notes C and Eb:

This can be used to suggest a Cm chord, a F7 chord, an Ab major chord, etc. Obviously using the same technique in hole 4 gives you the same notes an octave higher.

If you play the blow note and the overblow in hole 2 of a C harp, you get the notes E and G#:

This can be used to suggest an E major chord, a C# minor chord, etc.

If you play the blow note and the overblow in hole 6 of a C harp, you get the notes G and Bb:

This can be used to suggest a Gm chord, a C7 chord, a G7#9 chord, etc. Applying this technique to alternate tunings can give you many other possibilities

Again, these sounds can be somewhat rough and often tend to come out rather flat, so you may need to exercise some discretion in their use.

Similar sounds can also be produced whilst drawing, sounding a draw bend at the same time as the unbent draw note. Here is the lowest draw bend in hole 3 sounded along with the unbent 3 draw.

In this example it is played on a C harp, so the notes are G#/Ab and B, which could be used to suggest an E chord, or an Abm. The same technique can be used as a tonal or textural effect rather than as a harmonic device, adding a raucous edge to a note. Playing the 2 draw bend at the same time as the unbent 2 draw adds a dissonant attack which can be accentuated by amplification:

This can also be done on 1 draw and 4 draw and as the bent note is only a semitone lower than the unbent note this makes the effect even more dissonant, however I find it considerably harder to do than on holes 2 and 3.

You have probably noticed that if you hit the first draw note of a diatonic harmonica quite sharply, you get a raucous honking tone. In fact, this is often used to suggest an old-fashioned car horn:

The pitch of this note can often be made to go slightly sharp if you attack it just the right way (some harps lend themselves more readily to this than others), which can make it musically useful. The earliest recorded example I know of this is in "Sleepy Blues", recorded in 1927 by the Five Harmaniacs (available on RST Records JPCD-1505-2 "Harps, Jugs, Washboards and Kazoos" - click here for details), where the harmonica player uses this technique to obtain the flat third in the lowest octave whilst playing in first position. The same technique is featured in Willie "Red" Newman's 1936 recording of "St. Louis Blues", "Mountain Blues" by Jimmy Smith (an old-time harmonica player, not the famous jazz organist - this used to be available on an LP on the Roots label) and "Travelin' Man Blues" by the Saunders Twins. Unfortunately none of these tracks are currently available on CD, as far as I know.

This is what it sounds like:

Here I am playing the notes Bb Bb G Bb Bb A G on a G harp. The Bb is played by pulling 1 draw sharp and the effect is accentuated a little by playing the A slightly flat.

this article is taken from http://www.patmissin.com/