The first difficulty is due to the tonalities (to the 6 tonal accents which each evolve differently, according to the consonant on which the tonal accent is placed). The other difficulty is with specific Lao sounds for which there is no literal transcription in our language. It is often awkward to try and make a Lao word correspond to a word written in English, which will only be an approximation of the original pronunciation.
As an example, lets take the word pronounced "thao" (not to be confused with "tao" :-) which signifies sir, young man or boy. This term can be written 12 different ways, of which 10 give way to a literal sense and 2 have none.
We could go on indefinitely showing examples. "Kaï" is a perfect illustration : chicken, egg, far, near, sell, etc … often mixing a term and its opposite. Difficult to recognise, without a musically trained ear.
On to of this, there are regional accents, of which there are three main ones :
the northern one (Louang Prabang & Sam Nua) the most ’royal’
the central one (Vientiane) which is the most often used (especially for books)
and the southern one (Savannakhet, Paksé).
The Lao language system is very simple, being as there is no complex grammar, nor conjugations like in Latin or Anglo-Saxon languages. But its not because its a simple language, that its easy to learn; use of the Lao language is very difficult due to the tonal accents.