Could a program perform automated scale/mode detection beyond just the major and minor scales?

Question

The automated scale/mode detection programs that I am aware of such as Mixed in Key can only detect major and minor scales, in addition to the key. Could there also be programs that could perform automated scale/mode detection beyond just the major and minor scales? (e.g., detect if a song is using the Phrygian mode)

Answer 1

TL;DR: The concept of key as in "home pitch and the third above it in harmonic resting position" is much more widely applicable than the narrower concept of mode. For a piece in F Dorian, it's not wrong to tell (pop) musicians it's in F minor.

The authors of "Mixed in key" must have forgotten to explain what they mean by key and why it's useful for the mixing thing. I haven't tried it, but I assume that for a sample in C Dorian and another in C Phrygian it will say "C minor" for both, meaning that they would be mix-compatible in the intended approximate sense.

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First off, your question reveals a common misconception:

Could there also be programs that could perform automated scale/mode detection beyond just the major and minor scales?

I don't know this program, but I'm quite sure it doesn't detect scales. Key does not mean scale, it means the harmonic center pitch, and whether the third above it is minor or major. Key is not scale. For a key there is a "default" scale that's denoted in the key signature, because a lot of Western music tends to use those pitches more than others, so this reduces the average number of accidentals needed in sheet music notation. But a song in any key can use any pitch, the only thing that matters is the home note and third, then you know the key.

I am not currently aware of such programs, which would take any random music and declare that it should be categorized as being in one of the church modes. To get some understanding why that might be, read these questions and answers about the Music21 Python programming library

• Is there any way to find a key of song somehow mathematically/algorithmically?
• How does the analyze function work by taking 'key' in music21 library(python)? From a passed midi file, how can it determine the key and mode?
• Is it possible to determine the major/minor key of a song by just looking at the chords?

Basically, if you analyze entire songs, chances are that they don't mechanically stick to any single mode for the duration of the whole piece. There needs to be a sliding window and multiple simultaneous possibilities. AND the concept of key as in "home pitch and the third above it in harmonic resting position" is much more widely applicable than the more rarely applicable concept of mode. For a piece in F Dorian, it's not wrong to tell musicians it's in F minor.

Furthermore the algorithms are rather simplistic, they're based on simple statistics like what pitches are used most often.

In reality, the perception of harmonic balance is affected by all aspects of music like pulse, meter and rhythmic weight. Pure pitch relationship based harmony only exists in theory - actual music has a time dimension, and the dimensions of music are not completely separate and independent of each other. And perception also depends on each listener's personal history.

I haven't checked, but to me it looks like the "mode" classification in things like the mentioned Music21's analyze fuction says "major" or "minor" only meaning a coarse category relative to the key center (tonic, home note). It does not mean "100% ionian scale only" or "100% aeolian scale only". I suppose it means that the third above the tonic is mostly major or minor, and everything else can be anything. And this is actually a rather accurate description of how pop/jazz musicians of today understand the concept of key. *)

In this meaning, something in Phrygian would fall in the "minor key" category, because the third is a minor third. And for the rest of the pitches we don't care. Music in Dorian, Aeolian and Locrian would similarly go under "minor key". They are all minor modes.

To see if the "Mixed in key" application works like this, feed it something in C Phrygian and see if it says it's in C minor.

To actually tell whether something is "really" in a mode, modal, ... then we'll have to let a group of music theory and history nerds have a debate about it.

*) "Today": when I was young and learned pop music in the 1980s-1990s. If we really speak about literally TODAY, 2024, it seems that for many mouse+DAW pop makers, key means scale. Just like the OP in this question... Where is that harmful misinformation coming from. If these people figure out that a tune uses an out-of-scale note, their heads explode because the laws of physics were broken.