May I know how the rules governing the pronunciation of 地?
In the song, 吻别, the singer pronounces 地 as di.
冷得连隐藏的遗憾都那么地明显
leng de lian yin cang de yi han du na me di ming xian
However, a quick check with the Oxford Chinese-English Dictionary suggests that 地 is pronounced de when used
[with an adverb or adverbial phrase]
while the pronunciation of di is used when referring to distance, position, etc.
Is my interpretation of the Oxford Dictionary wrong?
Very interesting question.
Like what @AwQiruiGuo has said, 地 should be pronounced as [de] (in speech, that is). And indeed the mentioned singer does not speak perfect Mandarin.
However, this question has a more complicated background and should not be simply explained as the personal accent of the singer. Because in the case of songs, pronunciation variation kicks in.
Chinese Mandarin is a tonal language. But when the lyrics were sung, rhythm and beats can alter the tones. I'll take the lyric in the question as an example: Dictionary says 那 should be pronounced in 4th tone, but in this song, 那 is in 1st tone. Just listen to this song, and imagine what it would sound like if 那 is sung in 4th tone.
In lyric, when a character is on the downbeat, it is accented (stressed). If we mark all the downbeats, the lyric in the question will look like this:
冷得[连]隐[藏]的[遗]憾都[那]么[地]明[显]
The characters in square brackets are on downbeats.
In Chinese phonology there is a concept called 平仄, which deals with the arrangement of characters in poems (诗) and lyrics (词) according to their tones. 词 is an art form with strict metrical foot which is comparable to English poetry. You have to write each line of lyrics with specific number of syllables in specific stressed/unstressed order. The guideline of how you arrange the stressed/unstressed syllables was of course the original rhythm and beats of ancient songs, which unfortunately were most - if not all - lost in the history.
Ancient Chinese pronunciation was different from modern Chinese but you can roughly interpret 平 as stressed (1st and 2nd tones in modern Mandarin) and 仄 as unstressed (3rd, 4th and 5th tones in modern Mandarin). Although pop music does not follow ancient meters any more, rhythms and beats still impact pronunciation because it's only nature that people pronounce stressed syllables on downbeats.
With this in mind, now take a look again at the downbeat characters in the mentioned line of the lyrics:
冷得[连]隐[藏]的[遗]憾都[那]么[地]明[显]
连: 2nd tone, stressed. In this song, it sounds like 1st tone, still stressed.
藏: 2nd tone, stressed. In this song, it sounds like 1st tone, still stressed.
遗: 2nd tone, stressed. In this song, it sounds like 1st tone, still stressed.
那: 4th tone, unstressed. But in this song, it sounds like 1st tone, stressed.
显: 3rd tone, unstressed. But in this song, it sounds like 1st tone, stressed.
now back to 地 in question: should be 5th tone, unstressed. But in this song, it sounds like 1st tone, and is altered from [de] to [di].
Because [de] was 5th tone which is a very light one, if simply pronounced as [de] in 1st tone it just doesn't feel right. So traditionally when you want to stress [de5] you make it [di1]. And not only 地, but even 的 also follows this rule. I think this usage traces back to Chinese Opera. For example in The Legend of the Red Lantern (红灯记) there are some famous lines of lyrics：
穷人的孩子早当家
都有一颗红亮的心
where 的 is pronounced as [di], even if it's not on downbeat.
This might be historical reasons. According to some discussions in other forums, 'Di' pronunciation was common in almost all songs before 1995. After 2000, almost all are pronounced as 'De' -- the same as speaking. If you sing late songs with 'Di' sound, it sounds really weird, because it is no longer common in spoken languages.
的 地 得 as particles should be pronounced as de in the standard Mandarin Chinese. However, they are usually pronounced as di in singing.
90% Singers are pronouncing incorrectly. And even those wrongly pronounced songs are even more popular than correct ones.
In this case, the correct pronunciation should be [de].
Just fyi, the singer of 吻别 is 张学友 from Hong Kong. People from Hong Kong are not quite professional in Mandarin.
Update on May 4: sorry that I didn't check Jacky's original version on Youtube. He's pronouncing it correctly.
di?
的 can even be pronounced 'di' for emphasis. A lot of kids when they say 我的 will say "wo di" just to emphasize.
Something similar can happen with 地. Singers prefer to use the 'di' pronunciation - perhaps it sounds cuter. In some regions people also insist on reading 地 as 'di' and will tell foreigners likewise - but in MSM (Modern Standard Mandarin) it should, as oxford mentions, be read 'de'.
Edit: the only instance of this I can find in a dictionary is KEY dictionary, under '地' di entry they have the following explanation:
6 (suffix, forming an adverb from an adjective, e.g., gāoxìng 高興/高兴 "happy" + dì 地 yields gāoxìngdì 高興地/高兴地 "happily"; in this function often pronounced "de")
de entry:
{grammar} (variant pronunciation of -dì) (forming an adverb from an adjectiv, e.g., gāoxìng 高興/高兴 "happy" + de 地 yields gāoxìngde 高興地/高兴地 "happily")
