Low Interval Limits: Understanding the Basics #
Musical intervals, or the distance in pitch between two sounds, form the foundation of harmony. Chord structures, made up of intervals can sound ‘muddy’ or dissonant when played too low in an instrument’s range, depending on what intervals are present in the chord voicing. Low Interval Limits establish the acceptable limit below which chords will likely take on the ‘muddiness’. Being mindful of the lower limits of each interval allows you to get as low in the range as possible without crossing over Low Interval Limits.
Note that octaves (P8) are not included in the image above – octaves are generally acceptable anywhere in the range of the voicings.
What are Low Interval Limits?
In the context of music, “low interval limits” refers to a concept explored by music theorist Ernst Terhardt. It’s related to the perception of dissonance and consonance in intervals, specifically in the lower frequency range.
The idea is that, for low frequencies, smaller intervals (like minor seconds and major seconds) can sound particularly dissonant because of the way our ears process these closely-spaced frequencies. As pitches rise in frequency, our perception of their dissonance decreases. In other words, two low notes played together a whole step apart might sound much more dissonant than two high notes played at the same interval.
This is related to the psychoacoustic phenomenon of “beating,” where closely-spaced frequencies interfere with each other in a way that can be perceived as a rhythmic pulsation or “wobble.” At lower frequencies, this effect can be particularly noticeable and potentially unpleasant, hence the concept of “low interval limits.”
In practical terms, composers and arrangers might use this concept to inform their orchestration decisions. For instance, they might avoid closely-spaced intervals in the bass register but use them freely in higher registers.
Why Are They Important?
- Stay mindful of the mud: Keep your chord voicings in a healthy range where they remain clear.
- Achieve richest possible bass in voicings: Allows voicings to still play low notes in an instruments range without compromising the voicing’s clarity.
In Cymasphere, Low Interval Limits can be automatically avoided, ensuring that the intervals that make up voicings stay within a ‘healthy’ range.
