メロディック度
楽曲がどれだけ明確で覚えやすいメロディを持ち、はっきりとした音楽パターンに沿っているかを示します。メロディック度が高い楽曲は、わかりやすく印象に残る楽器やボーカルラインが特徴です。
アコースティック度
楽曲が、電子楽器やデジタル合成音の代わりに、どの程度アコースティック楽器（ピアノ、ギター、バイオリン、ドラム、サックスなど）に依存しているかを示します。
ヴァランス
楽曲のハーモニーやリズムによって伝わる音楽的なポジティブ度や感情的トーンを示します。値が高いほど幸福感、興奮、陶酔などの感情を表し、低いほど悲しみ、怒り、憂鬱などの感情を表します。
ダンサビリティ
テンポの安定性、リズムパターン、ビートの強調などの要素を組み合わせて、楽曲が踊りやすいかどうかを示します。ダンス向きの楽曲は、一定のテンポ、反復的な音楽構造、強いダウンビートを持つ傾向があります。
エネルギー
楽曲の知覚される強さを示し、テンポ、音量の変化、音の密度などによって影響されます。エネルギーが高い曲は、力強いリズムや密度の高い編成を特徴とし、エネルギーが低い曲は、音の間隔が広く、テンポもゆったりとした構成になる傾向があります。
歌詞
(And I can't look up and I can't look down
When the whole wide world reveals its death
And I can't take a breath 'cause I haven't escaped
And I haven't escaped because I can't take a breath)
Oh zookeeper, we're gonna help each other through
Zookeeper, I don't trust anyone but you
Leave the enclosure, lower our gaze
Brace for the crush, here it comes, brace for the craze
(And I can't buy into the world that's sold
But I can't afford to buy a ticket out
And I can't reply to anything I'm told
But they say they're just telling me to open my mouth
And I can't shake the feeling there was something else
There was something I believed in that got me here
But I'm afraid to go back and find what it was
Because the only belief that I held was fear)
Oh zookeeper, all my life through
Zookeeper, it's been only me and you
We govern the jungle, we scuttle the ark
There go the cameras, here comes the dark
Here comes the dark
(And will you leave me behind because I cry too much?
Well if you do then you know I'll cry and cry
Or are you leaving 'cause you've never known another touch
And you wonder what it's like on the other side?
And the further you go, the less I care
And the less I care, then the further you go
And the smarter I get, the more I want to learn
But the more that I learn, the less I realize I know)
'Cause there's
There's nobody left
There's nobody left
There's nobody left
There's nobody left but you and me
There's nobody left
There's nobody left
There's nobody left
But you and me
(And everything that's new decays to something old
And "new" is just a word, just an adjective
And every part of speech that I conceive afresh
Will do nothing to change the fact that it's live
Or die, the two, the irreducible pair
And it's yes or no, and it's you or me
And it's stay or go, and it's earth or air
And it's fast or slow, or it's in between)
Oh zookeeper, d'ya think we'll pull through?
Zookeeper, and do we really have to?
We could've stayed, we could still pretend
But here come the birds of prey
Here comes the end
Here comes the end
(And it's up or down, and it's zero or one
And we're made of ghosts, who're all keeping score
It's all in the past or it's still to come
And I feel like I'm the only one who cries for more
'Cause time is just one way, and a circle's closed
And everyone I know retains a name
Still I can't look up and I can't look down
And for all the change, it's all the same)
And there's
There's nobody left
There's nobody left
There's nobody left
There's nobody left but you and me
There's nobody left
There's nobody left
There's nobody left
But you and me
There's nobody left
There's nobody left
There's nobody left
There's nobody left but you and me
(And if I stride into the heart of a factory
Walking tall and fast so that no one asks
Could I lay my head down on the iron press?
And could I push the green button and end it fast?
There's a black hole spiral with no inside
Where nothing escapes and death is just a flash
But to the bear in the cage is there a slowing of time?
Does the split second noise just last and last?)
There's nobody left in the world
In the place of predator and prey and boys and girls
There's nobody left in the wild
Ain't got no use for words like "animal" or "child"
(And does the lion grow love like wings of milk?
And does the meat of my bones rise up and sing?
And does my soul take flight into calcium dust?
And does the map of the world blow apart in the wind?
And does the boat on the water dissolve in tears?
And does clearing in the forest mate intention with math?
Is the emergence of a tumor just a god who tries
To break into our world by the shortest path?)
Zookeeper
Come on, open your heart up, open my cage
Here comes the future
Here comes the rage
(And does the flailing of my body on the foundry floor
Give a scent of honey and a scent of luck
So that the workers and overseer can't ignore
The little moon glow breeze by which they're struck?
And will we meet in the morning on the day we die?
Will we chase our shadows like we never grew up?
And will we laugh to the comedy of nuclei?
And will we drink ourselves deep into the holy cup?
And your very first word was your very last choice
If your daughter doesn't get you then the government will
I'm just hanging onto life for the sake of my cats
And if I were their size, they would probably kill me too)
Written by: Alex Reed
