Hello, can anyone explain the stressing rule behind the falling tone? I have noticed it can be prononced it in 2 ways. Is there no right or no wrong in pronounciation of the stress?

The only difference i think you'll find in the falling tone is the vowel length.

Listen to words like kluay - banana and hong - room for the long vowel.

For the short vowel listen to gung - shrimp.

Basically any of the mid or high class consonants with the mai toh tone marker. There are some exceptions for low class falling tones so concentrate on the others first and maybe you'll hear the difference.

Perhaps what you're hearing is when people extend the vowel for emphasis? For example, ใช่ is often pronounced ช่าย, and when being given special emphasis, it's drawn out even longer. It's not just falling tone, but perhaps it stands out because key grammatical words that often get emphasized all have falling tones: ใช่, ไม่, ได้ etc.

There are, in general, lots of words which have long vowels when they are stressed and short vowels when they are not, but again that's not specific to words of a particular tone. Like น้ำ -- pronounced น้าม when stressed (ex. หิวน้ำ pronounced [หิว-น้าม]), but pronounced more like นั้ม when unstressed (ex. น้ำเปล่า [นั้ม-เปฺล่า], น้ำแข็ง [นั้ม-แข็ง]).

Thai definitely has some complex stress patterns, but the rule of thumb is that Thai stresses the last syllable of words (whereas English tends to stress the first -- think apple vs แอปเปิ้ล).

Is this the type of thing you're getting at?

Rikker thanks for the bit of analysis. Off topic, can you please explain to me about why is 'khaaw® thot(F)' pronounced as 'khaaw(M) thot(F)', and as often i have heard 'khaaw®' pronounced mid tone. Is there any definition in this so-called Stressed Syallables. Often the written pronounciation is not often pronounced in daily colloqial conversation. Thanks

Just like vowel length, tone too can change when unstressed. It's not conscious (and Thais might even argue that they don't do it), but it's a natural process.

The most common vowel to lose its tone when unstressed is อะ (short a). Take two words like ขนม (kha-nom 'snack, dessert') คะนอง (kha-nong 'boisterous'). If read carefully, and in isolation, the tones of ขนม's two syllables are low then rising [ขะ-หนม]. Compared with คะนอง, whose tones are high then middle [คะ-นอง].

In theory the two kha- syllables are pronounced different. But in flowing speech, initial syllables kha- in both words are pronounced with a "bleached" middle tone. This is even though in theory a Thai short vowel can't have a middle tone at all. It's just a phonetic process that occurs largely unnoticed.

So I think you're right that the ขอ in ขอโทษ, being the unstressed syllable in such a commonly uttered phrase, is often not fully pronounced. If this kind of phonetic "bleaching" continues, it might end up a contraction, just like the polite particle ครับ used to be two words: ขอรับ.

[Aside: ขนม has a similar story. It's a contraction from ข้าวนม (ข้าว 'rice' and the นม part is borrowed from Khmer នំ /num/ 'dessert' -- not related to the Thai word นม 'milk, breasts'). Presumably, as ข้าว became reduced to simply ข-, the word นม would've taken on a rising tone, because of what thai-language.com calls the "clustered consonant tone rule" whereby a high consonant transfers its tone to the second syllable.]

Sawasdee ka

According to this guy, the falling tone does not really fall in unstressed syllables. More on Thai stress, check out this video:

I hope this helps.

Funny. When I read the OP I was sure he meant the tone symbol can be pronounced 2 ways, which is correct and depends on consonant class. But I guess he really meant the tone.