Chord processing method and chord processing device

A chord processing device comprising:

• a memory storing instructions;
• and
• a processor configured to implement the stored instructions to execute a plurality of tasks, including:
• a receiving task that receives a first chord consisting of plural notes among a plurality of first chords included in a chord sequence of a musical piece;
• an analysis task that determines whether the first chord is a subject chord;
• a converting task that, in a state where the analysis task determines that the first chord is the subject chord:
• determines whether the first chord satisfies a prescribed chord-related condition relating to the first chord and a second chord that relates to the first chord, wherein:
• the prescribed chord-related condition at least one of:
• the first chord that has been determined to be the subject chord not including, as a root, a note providing a prescribed interval relationship with a keynote of a key;
• or
• the second chord, which is selected from among plural second chords, providing a highest degree of similarity with the first chord among plural chords that is higher than a threshold value in a degree of the similarity,
• satisfying the prescribed chord-related condition allows an unconverted chord sequence to a converted chord sequence,
• the unconverted chord sequence is where the first chord is not converted to the second chord, and
• the converted chord sequence is where the first chord is converted to the second chord;
• converts the first chord to the second chord in a state where the first chord satisfies the prescribed chord-related condition;
• and
• not convert the first chord in a state where the first chord does not satisfy the prescribed chord-related condition.

A non-transitory computer-readable medium storing a program executable by a computer to execute a chord processing method comprising:

• receiving a first chord consisting of plural notes among a plurality of first chords included in a chord sequence of a musical piece;
• determining whether the first chord is a subject chord;
• in a state where the determining determines that the first chord is the subject chord:
• determining whether the first chord satisfies a prescribed chord-related condition relating to the first chord and a second chord that relates to the first chord, wherein:
• the prescribed chord-related condition includes at least one of:
• the first chord that has been determined to be the subject chord not including, as a root, a note providing a prescribed interval relationship with a keynote of a key;
• or
• the second chord, which is selected from among plural second chords, providing a highest degree of similarity with the first chord among plural chords that is higher than a threshold value in a degree of the similarity,
• satisfying the prescribed chord-related condition allows an unconverted chord sequence to a converted chord sequence,
• the unconverted chord sequence is where the first chord is not converted to the second chord, and
• the converted chord sequence is where the first chord is converted to the second chord;
• converting the first chord to the second chord in a state where the first chord satisfies the prescribed chord-related condition;
• and
• not converting the first chord in a state where the first chord does not satisfy the prescribed chord-related condition.