Harmonic is about notes sounding together. In music, when several notes are played or sung at the same time and they fit each other, that is harmony — and 'harmonic' is the adjective for it.

Harmonic Harmonic is about說的是 notes sounding together音符一起發聲的事 In music在音樂裡 when several notes are played or sung at the same time當好幾個音同時被彈奏或唱出 and they fit each other而且彼此搭配得起來 that is harmony這就是harmony（和聲） and 'harmonic' is the adjective for it而harmonic就是它的形容詞。

So 'harmonic structure' means how the chords in a song are built and how they move; a 'harmonic change' is the moment the chord under the melody changes. Notice the split: 'melodic' is about notes one after another (the tune you hum), 'rhythmic' is about time, 'harmonic' is about notes stacked up at the same moment.

So所以 'harmonic structure' means「harmonic structure」指的是 how the chords in a song are built and how they move一首歌裡的和弦怎麼組成、怎麼進行 a 'harmonic change'「harmonic change」 is the moment則是 the chord under the melody changes旋律底下的和弦改變的那一刻 Notice the split請注意這個區分 'melodic' is about notes one after another「melodic」說的是音符一個接一個（也就是你哼的那條旋律） 'rhythmic' is about time「rhythmic」說的是時間 'harmonic' is about notes stacked up at the same moment「harmonic」說的是同一時刻疊在一起的音。

Music teachers and people who write about music use this word a lot; ordinary listeners rarely say it — they just say 'the chords'.

Music teachers and people who write about music音樂老師和寫音樂文章的人 use this word a lot常常用這個字 ordinary listeners一般聽眾 rarely say it很少這樣說 they just say 'the chords'他們就只說「和弦」。

There is a second life for this word in science and maths, where a 'harmonic' (used as a noun) is one of the higher, quieter notes that hides inside one played note and gives an instrument its colour; a violin and a flute playing the same note sound different because their harmonics differ. From there engineers borrowed it for any wave that repeats at a whole-number multiple of a base rate, and you meet it in electrical work with no music anywhere in sight.

There is a second life for this word這個字還有第二種人生 in science and maths在科學和數學裡 where a 'harmonic' (used as a noun)「harmonic」當名詞用時 is one of the higher, quieter notes是比較高、比較安靜的音之一 that hides inside one played note藏在一個音裡面 and gives an instrument its colour讓一件樂器有自己的音色 a violin and a flute playing the same note小提琴和長笛彈同一個音 sound different聽起來卻不一樣 because their harmonics differ因為它們的泛音不同 From there engineers borrowed it從那裡工程師借用了這個字 for any wave that repeats at a whole-number multiple of a base rate用來指任何以基頻的整數倍重複的波 and you meet it in electrical work你會在電機工作裡遇到它 with no music anywhere in sight完全跟音樂無關。

There is also a warm, loose use — 'a harmonic blend of flavours' — where someone means only 'the parts go well together'. That use is real, but it is a stretch from music, and some careful writers dislike it.

There is also a warm, loose use還有一種溫和、鬆散的用法 'a harmonic blend of flavours'像「a harmonic blend of flavours」（風味和諧地融合） where someone means only這時候意思只是 'the parts go well together'「各部分搭配得很好」 That use is real這種用法是真實存在的 but it is a stretch from music但這是從音樂那邊拉遠了一點 and some careful writers dislike it有些講究的作者不喜歡這樣用。