Before you buy yourself or friend a harmonica, be sure to read the following to learn the differences between the different types and categories of harmonicas. Aside from the standard diatonic and chromatic harmonicas, most other types are for special purposes or special effects and not as commonly used. Most professionals primarily play diatonic or chromatic harmonica.
- DIATONIC HARMONICAS:
The standard 10-hole major diatonic harmonicas come in all 12 keys of music and allow you to play a complete 7-note major scale of the key of the harmonica. Many additional notes from outside the major scale can be acquired by "bending" certain draw (inhale) and blow (exhale) notes. Most professional players are predominantly diatonic players. Diatonic harmonicas are typically used in blues, rock, country, and folk, but are found in nearly all styles of music.
- CHROMATIC HARMONICAS:
The chromatic harmonica has a button on the side, which when NOT pressed in, allows you to play a normal major scale in the key of the chromatic. With the button depressed, you have all the missing half-step notes in-between the major scale notes. This allows you to play in any key and any type of scale.
- TREMOLO HARMONICAS:
Tremolo harmonicas are Diatonic models constructed with double holes (sometimes 8, 10, 12, or more sets of double holes), each containing two reeds tuned to the same note, one tuned slightly higher than the other. Since both reeds are either blow or draw, when played, both will sound together and the slight difference in tuning creates a vibrating or tremolo effect.
- OCTAVE-TUNED HARMONICAS:
Octave harmonicas are similar to Tremolo models in reed layout and musical range. Instead of having reeds tuned to the same note, however, each double hole has one reed tuned an octave apart from the other.
- ALTERED TUNED DIATONICS:
For players that do not play chromatic harmonica, but may have the need for additional notes and scales in their playing, they can pick up an altered (or special) tuned (actually re-tuned from the standard major scale tuning) diatonic.
- OTHER TYPES:
Additional types of harmonicas are available for special purposes like harmonica trios, groups, or orchestrals. Most of these are made by the Hohner Company, but other companies such as Seydel and Suzuki carry some as well.