Tone changes in my L1

I've been talking to E-Ching over email, and I've discovered that my L1,
Hokkien, appears to have changed its tones from the original mainland
Hokkien. (Taiwanese is closer to the mainland Hokkien, AFAIK.) I just
thought it'd be interesting to conlang members as an example of tone
changes in a real language.

The following is a comparison of the tones in my L1 compared to the tones
in Taiwanese:

Tone    Taiwanese       Penang Hokkien (my L1)
1       high level      medium(?) level. I call it medium because tone 2
                        start out higher (sometimes much higher) than tone
                        1.
2       high falling    high *rising*. Although sometimes high-falling is
                        used, it has practically become high-rising now.
                        (Another reason why I call tone 1 "medium": if it
                        were already high, tone 2 would blow the roof :-P)
3       low falling     low level. It's probably the same as low falling,
                        but I just can't, for the life of me, detect any
                        falling pitch when I'm pronouncing this tone.
4       low falling     low level. To my ears, this is identical to tone 3.
        (clipped)
5       rising          low rising. Probably the same as rising, but in my
                        L1, this is *definitely* between tone 3 and tone 1.
7       mid level       low level. This one appears to have merged with
                        tones 3 and 4, or perhaps have just plain disappeared
                        and words that originally had this tone has picked
                        up another tone.
8       high clipped    medium level. Again, this is identical to 1, to my
                        ears.

*Note: E-Ching pointed out that the tones 1&8 and tones 3&4 are probably
different only in the presence of a stop, so perhaps that's why I can't
hear the difference, since I regard stops as part of the consonantal
structure rather than the tonal structure.

Any comments? I'm just curious if there are any general observations about
how tones can change in tonal languages, esp. since I plan to make a tonal
descendent from my current conlang one day :-)


T

--
MAS = Mana Ada Sistem?