Dissonance is defined by Webster’s dictionary as “a lack of agreement or harmony between two or more musical sounds; a harsh, inharmonious, or discordant sound; or an uncomfortable feeling of discord between two ideas, facts, or situations.”
The following excerpt is a musical phrase that may sound dissonant to some:
A♭ B♭ C D♭
In order to find the answer, one must analyze the musical phrase in order to determine if it is made up only of consonant intervals or if there is a dissonant interval present.
A consonant interval (or chord) is any two or more notes played at the same time that are in agreement and sound pleasant together. The following intervals are considered consonant: perfect octave, perfect fifth, major third, minor third, major sixth, and minor sixth.
The musical phrase written above is made up of only one type of interval: minor third. A minor third interval is considered to be a dissonant interval because it creates tension and an uncomfortable feeling when compared to other intervals.
Therefore, the answer to the question “Is the following excerpt dissonant?” is yes.