Tone question

[nipponman]

My question deals with tones but not like "how do I say the fourth tone".

I have this dictionary (English-Chinese (Pinyin) Pocket Dictionary) and it says in the back, "Following a first, second or fourth tone, the unstressed syllable is pronounced like a very short light fourth tone. The pitch of the

beginning of the shortened fourth tone follows naturally from the sound pattern of the preceding syllable..." and it has some examples

• 
  丫頭
  拳頭
  木頭
  裏頭
  

but then it says that ya1 tou2 goes to ya1 tou4 and that quan2tou2 goes to quan2 tou4 and that mu4tou2 goes to mu4tou4 and that li3tou2 goes to li3 (shortened)tou1, and it gives the rules as follows: "

1.After a first tone the shortened fourth tone begins at a pitch slightly lower than the first tone.

2.After a second tone, the shortened fourth tone begins at a pitch slightly higher than the second tone

3.After a fourth tone, the shortened fourth tone begins at a pitch slightly lower than the fourth tone.

4.After a third tone the unstressed syllable is pronounced as a short light first tone."

Now I have never heard these rules before, and I showed it to my chinese friend and she didn't know for sure wether or not they were bad (but she was leaning towards bad) so I had to come ask you guys.

Thanks in advance for any help!

P.s. sorry for the long post

[kentsuarez]

After 10 years in Taiwan (with reasonably good pronunciation), those rules sound pretty squirrelly to me. Ignore them completely, and just keep your ears open instead.

My experience is that although some mainland speakers will convert those unstressed syllables to a neutral tone, here in Taiwan they remain in their original tone.

[carlo]

I think whoever wrote this had just read Chao Yuan-ren's early hypothesis that the neutral tones after 1st, 2nd and 4th tone have a descending pitch contour, while after the 3rd tone it's sort of flat.

This difference is so subtle that you wouldn't even consciously hear it (in connected speech, it might disappear altogether). So nobody teaches neutral tones this way. The distinguishing feature of a neutral tone is that it is very short, in terms of duration: so basically it has no contour. Think of a neutral tone as a single note, whose pitch depends on the pitch contour of the previous tone. On a five-note scale from 1 to 5, you have Tone 1=55, Tone 2=35, Tone 3=211, Tone 4=51. Then

丫头=ya55tou2

拳头=quan35tou3

木头=mu51tou1

里头=li21tou4

Simply put, high note after a third tone, low note elsewhere.

[nipponman]

Thank you guys, I thought I had some hard work ahead of me in memorizing (and implementing!) those rules.

Thanx again.