The hardest bars in popular piano pieces

One bar per piece carries the trouble

Most of the pieces people play most on MasterPiano are short: folk songs, carols and simplified classics of 8 to 16 bars. They look even. The data says they are not. In the median piece, players’ error rate in the hardest bar was 1.5 times their rate in every other bar, and in 26 of 50 pieces it was at least 1.5 times.

The hard spot also survives a change of arrangement. In the level 8 Jingle Bells and the level 1 “I Can Play Jingle Bells”, played by different groups of people, bar 15 is the hardest (3.0x and 2.1x the rest of the piece). Two Yankee Doodle arrangements, at levels 5 and 1, both peak at bar 7.

What the hardest bars have in common

We read the notes of every bar from the public score of each piece and tested eight traits. For each, we compared how often it appears in the hardest bars (49 with readable notes) and in all 550 other bars, and checked within each piece whether bars with the trait were harder than bars without it.

Leaps of a fourth or more

A leap here is a jump of five semitones or more between two notes in the same hand: a fourth, a fifth or wider. These bars make up 24% of the hardest bars and 15% of the rest. The pattern holds inside pieces too: in 26 of the 30 pieces that have bars with and without a leap, the bars with one were harder on average.

The bar where a repeat changes

Many simple tunes repeat a phrase and then change its ending. We flagged a bar when the two bars before it match an earlier passage note for note, but the bar itself does not continue the way it did the first time. Only 31 bars do this, yet 5 of them are the hardest bar of their piece, including Jingle Bells bar 15, Hänschen Klein bar 7 (1.8x) and Deck the Halls bar 7. On average their error rate ran 3.7 points further above the rest of the piece than other bars, and they were the harder bars in 13 of the 19 pieces that have one.

This fits an older finding. When the music psychologist John Sloboda gave pianists scores with deliberately altered notes, they often played the notes they expected instead of the notes printed (Sloboda, 1976). Our data cannot show why players slip at these bars, only that they do.

Weaker or no patterns

Bars with more notes than their piece’s average lean the same way, but weakly: they are 61% of the hardest bars and 52% of the rest, and their gap above the rest of the piece is only 1.3 points larger. Dotted notes (12% against 20%) and both hands playing (43% against 35%) show no consistent effect. The opening bar is the hardest in 8 pieces, the final bar in only 2. Sharps, flats and naturals are too rare in these mostly beginner pieces to judge: 15 of 599 bars have one.