Accordion/Anglo German Concertina
The concertina was developed before the accordion, to compete against reed organs which appeared about the same time, with similar reed technology. This was accomplished with ten buttons. This gives the instrument a complete octave for either hand. An extra extra button plays notes above or below the octave. There are several different patterns of systems of concertina and accordion. Many designs are found, but most contemporary manufacturers follow the C/G anglo-German pattern pictured.
If one wanted to play 'serious' music with more range and subtlety, one might select a less convenient instrument with more buttons and bigger bellows. The advantage of the concertina is that it provides both melody and harmony, in an affordable portable instrument. Unlike harmonica, it allows the operator to sing at the same time. There are several ways to play the concertina. In practise, most concertina players will blend methods of play to suit the occasion. For example, an Irish folk player may thrown in occasional chords, for emphasis.
In this article, the right hand refers to the treble notes, left hand refers to the bass notes. In practise, left handed people sometimes invert the concertina and play treble with dominant left hand. This method works better for concertina than accordion (Bass button rows slant the wrong way on accordion)
Single voice. Taking advantage of the three octaves to play a single note, at a time, over a wide range. Play involves memorizing the sequence of bellows action as well as the location of buttons corresponding to the notes. This may sound easy, but in fact can be the hardest to learn, as melodic tunes are often played very rapidly. This type of play is often heard in association with other melodic instruments played presto (160bpm), such as tin whistle or fiddle. Using this technique allows the three F# notes to be use as accidentals.
Two voices. Involves playing one or more notes with each hand simultaneously with each bellows action. The sound produced is fuller. The complexity of learning these combinations can be daunting. Duet play was seen in hymns, and anthems, such as arrangement of 'God Save The Queen' in Sedgwick's 1865 manual, but many later manuals show only melodic play.
Another example is "Only a Pansy Blossom" 1888 by Frank Howard seen []
This method involves learning the sequence of key strokes for both hands. People trained in piano or accordion may prefer repetitive 'Oom Pah' style left hand bass, found in rhythmic play. When only two notes are played at any time, they are not strictly chords. Very full sound is produced with chords involving three or more notes.
Multiple voices. This method involves playing a complete melody with the right hand, while the left hand plays alternating bass notes and chords to suit the melody. For example, alternating C and C Major while playing melody on the C row.
The C and G rows of buttons on an Anglo-German concertina have identical intervals. If you learn to play a tune on the C row, you can use exactly the same combination of finger strokes and bellows action to play the same tune in the Key of G, half an octave higher. This helps performers to capitalize on the inevitable repeats, found in musical notation and extend the length of the piece being played. This technique requires enough musical theory for the player to find music in C or G. Music not in these keys must be transposed from the original key to an arrangement that suits the concertina.
One huge advantage of the layout is that the majority of buttons are arranged in chords, so that playing a combination of buttons, in a row, while pulling or pushing, creates a triad or major chord. For example: In the C row of the Right hand, when one squeezes the bellows, all the notes are between the lines in sheet music. When the bellows are drawn apart, all the notes fall magically onto the lines.
A disadvantage to this mode of play is the limited range of the available octave (Right hand C row has from B3 to A4). This means that it is necessary to 'wrap' the tune. Notes lower than this octave are played a perfect octave higher. Notes too high must be transposed down. If you can read music, this is not hard to accomplish, even though the sound produced may initially be counter-intuitive, once the speed and harmonic elements are added, the tune produced sounds better in context. There is an extra button in each row, which extends the range by two notes above the octave. The extra button can also be used for trills and replacing missing accidentals. The bellows are small enough that rhythmic play can exhaust the air reserve easily.
An example of rhythmic play is found https://youtu.be/MPjQG8BkVmQ
Meta-Harmonic (Jazz/Blues) play
Skilled concertina players often develop the technique to create 'bent' melodies by playing several melodic notes at the same time, or playing melodies in keys other than those included in design. The concertina does not provide a full chromtic scale. This technique involves developing 'false' or approximate base chords that sound appropriate, even if they are not musically sound.
The cost of this approach is that the buttons are not laid out in linear fashion like a piano or guitar. One must practise enough to learn the location of the notes. This may seem alarming, but with hands in the first position covering the top four buttons with either hand, one finds that the buttons form an octave. In harmonic play, There are really only seven notes to learn (one octave). Since there are only four buttons or eight notes, this makes the job much easier.