Friends,
We have updated
http://www.thai-language.com/ref/irregular-words at the Reference tab by addition as Section 4. This sections catalogs words with "irregular pronunciation" arising from expanded consonant clusters where the normal first consonant in a cluster is replaced by a syllable.
The word
ตรวจ is pronounced with a low tone because in the initial consonant cluster "
ตร" the tone governed by the low-class consonant "
ร" is modified by the mid-class consonant "
ต" to produce an overall low tone word. The derivative word "
ตำรวจ" also has a low tone, even though the word is now composed of two syllables. Other words affected by this exception are
ประโยค,
กิเลส, and
กำเนิด.
These words constitute a category of "exception" because many other words do not follow this pattern. For example, some words require a "
ห นำ" to convert the second syllable to a low tone. See
ประหยัด and
ประหลาด, for example.
For more information of consonant clusters, see
http://www.thai-language.com/ref/double-consonants and
http://www.thai-language.com/ref/cluster-tone .
If you have any other additions to this or the other category, please post them here and we will make the updates.
Thanks.