The harmonica has been part of world culture since 3000 years ago in China with a simple reed instrument called “sheng“. The famous German-based Hohner Company brought the harmonica to America in the 19th century, where it became associated with American blues, jazz, folk, and country music. However, not every harmonica is the same, although they share similar shapes and functions.

The different types of harmonica include the diatonic and chromatic varieties as well as variations of these styles, such as the tremolo and octave harmonicas. There are several varieties of specialized orchestral harmonicas, including the horn, bass, and chord style harmonicas.
Diatonic harmonica’s distinctive sound is famous in blues, rock, and country music, while the chromatic harmonica is the king of the jazz and classical music realm. If you plan on taking up the iconic ‘mouth harp,’ here’s a breakdown of the types of harmonica you might choose.
Diatonic Harmonicas
Diatonic harmonicas have a distinctive sound often associated with blues, country, and folk music. Their long association with the siding scales of Blues has earned the diatonic harmonica the nickname “blues harp.” Diatonic harmonicas are typically ten holes and are set to one key and come in all 12 keys of music.
The diatonic works through air vibration on a series of reeds within the harmonica. The longer the reed, the lower and deeper the sound it creates, while shorter reeds make up high notes. By either blowing or drawing air from the harmonica, the musician can play all 19 notes on their diatonic harmonica.
Each diatonic allows the player to play a complete seven-note scale in the chosen key, but that is not all. Through a process of “bending” and “overblowing,” the musician can slide the notes to make up a full scale. Bending involves sliding the note down by inhaling, while “overblowing allows the player to raise the note by blowing out.
Diatonic harmonicas come in two main sizes:
- The 10 holes or 20 reed variety with a 3-octave range
- The 14 holes or 28 reed variety offers a 4-octave range.
Furthermore, the diatonic also comes in a variety of scales which include:
- Richter scale (which is the regular major scale.)
- Natural Minor scale, which is the one used typically in western music
- The Harmonic Minor is found in east European music as well as Arab and Gypsy music.
Chromatic Harmonicas
The chromatic harmonica uses a sliding bar to direct air from the mouthpiece to the selected reed plate. The design typically encompasses what is called a “Machino Tone,” which controls the airflow through a lever-operated flap at the rear of the harmonica.
So musicians can choose whether to play the normal major scale in the chromatic key or operate the button to access a variety of missing half-step notes in between the major scale.
To put it in another way, the button allows the player to access the “black keys” on the piano as well as all the white keys if the button is not pressed, giving the full range of notes to play.
Although the chromatic is king in the jazz realm, it is also popular in other styles of music. Stevie Wonder brought the chromatic into mainstream music in his own inimitable style. Most chromatic harmonicas use “solo” tuning for the note layout based on a 4 hole pattern with blow notes of ‘CEGC’ and draw notes of ‘DFAB.’
The main difference between achromatic and diatonic harmonica is that the physical design of the chromatic with wind saver valves does not lend itself to bending as in the diatonic harmonica.
However, the button allows players to access the tones typically bent in the diatonic playing. At most, the chromatic can deliver a bending effect of a quarter to a half step.
Sizes of chromatic harmonicas may differ, typically into:
- The 10 hole chromatic offers 40 notes and a 21/2 octave range. This harmonica is highly portable and compact. However, it has an incomplete range at the top end, making it more limited in scope.
- The 12 hole variety offers 3-octave ranges and 48 notes. The 12 holes chromatic harmonica is a great introductory harmonica as it is easy to grasp and play. Purchasing a 12 hole in the key of C is highly recommended.
- The 14 hole variety offers 56 notes.This variety of chromatic offers an extra octave below C but is difficult for a beginner to master its full range.
- The 16 hole variety offers 64 notes.This chromatic variety lies between the 12 and 16 hole variety and has a range of 31/2 octaves, The larger size makes it more challenging to play, and one needs extensive practice to master its range.
Famous players of this instrument include:
- Toots Thielemans
- Larry Adler.
Tremolo Harmonicas
The tremolo harmonica creates a unique wavering tremolo sound, something akin to the sound of an accordion or organ. The tremolo has two reeds per hole that are set apart, with one slightly sharp and the other slightly flat in sound.
These two reeds create this wavering sound by being slightly out of tune with each other and their vibrations acting off against each other.
A tremolo is also a form of diatonic instrument, meaning that each harmonica is set to one key, and musicians carry multiple tremolos to encompass the full range of keys. Unlike the standard ten-hole harmonicas, the blow and draw reeds don’t share a single chamber, allowing the player to isolate each reed.
However, the instrument lends itself more to effects and simple melodies than the standard diatonic or chromatic harmonicas. The tremolo is used mainly for special effects and does not lend itself to note-bending such as the blues or complex techniques.
Tremolo harmonicas are famous worldwide, especially in East Asia, and a common choice of traditional western folk music. However, the tremolo has a greater range in parts of Asia such as China, Korea, and Japan and is used in music as diverse as folk to classical and ensemble playing.
The most common varieties of tremolo are the:
- 20 hole
- 21 hole
- 24 hole
Octave Harmonicas
The distinctively curbed octave harmonica is similar to the tremolo and produces a striking and full sound. Although the octave harmonica also uses the double reed structure of the tremolo, the reeds are set an octave apart from one another. The octave creates a rich double sound of a basic note and a higher octave note, but without the tremolo sound vibration.
Like the tremolo, the octave harmonica is a diatonic instrument that is set to one key. Although a skilled player can overblow and bend an octave harmonica, it is challenging to do so. The sound of the octave harmonica is reminiscent of German folk music.
Orchestral Harmonicas
Orchestral harmonicas encompass a range of specialized harmonica types to be used for ensemble play and orchestra. These varieties of harmonica include:
- Bass Harmonicas. These harmonicas play in the lower range and support the rhythmic section of the orchestra. Bass harmonicas use a sliding bar like a chromatic harmonica, and the lower part is tuned to a specific scale.
- Chord Harmonicas.Chord harmonicas offer up to 48 types of chords and perform the role of rhythm accompaniment and pads as the stringed instruments usually provide.
- Horn harmonicas.These chromatic harmonicas fulfill the role of bass with their larger reeds and enclosing ‘horn,’ giving them the part of brass in the orchestra.
Closing Notes
The harmonica has become an integral part of American music and culture, and its distinctive sound is evocative of the rolling plains of the old American West. The harmonica, once mastered, offers an astonishing array of sounds and effects that are unlike any other musical instrument.
If you are new to the instrument, the expert suggests that the diatonic variety is the easiest for a beginner to learn how to play.
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