Now THAT is interesting. Thanks for pointing that out Woodrow. I often learn things from your posts So the tonal nature is in itself qualitative, as opposed to gregorian chants which are stylistic (or done to "honor" the spirit moreso than to prove the message).
I am a beginner learner in reading/reciting the Qur'an properly, so I might not be able to explain to you the full nature/complexity in reading the Qur'an
properly.
Each letter in Qur'an arabic has their own special makhraj (makhroj), it means the source of the sound of the letter. it is not like saying "A, B, C, D" where it does not matter how you say the letter and where it comes from. There are 5 global makhraj and 17 specific makhraj.
In order to be a good qari/qariah (reciter of the qur'an) and hafiz/hafizah (memoriser of the qur'an), this first basic step must be mastered, because you will not be able to convey the full meanings of the words and sentences without pronouncing the letter perfectly.
And then you also have to master the sifaat (nature) of the letter. The sifaat of the letters are divided into 2: those that have the opposites (5 sifaats) and those that do not have (7 sifaats). The sifaats depend on whether you emit the sound in hard or soft, in clear or vague, in strong or weak or medium, in rising tone or lowering tone, attached or separated, whether it sounds like bird, or vibrate, or long etc. These makhraj and sifaat give certain characteristics to each and individual letters.
And only then you learn about tajweed which is the laws of the sound of the letters/words depending on their marks, locations and interactions with other letters (huruf), where to stop, where to pause, where to read long, where to read short, etc. Learning tajweed properly is not easy but there are qur'an text which are completed with tajweed marks to help beginner like me reading the Qur'an properly. Now you understand that it is essential that to recite the qur'an properly you MUST have a teacher/instructor, and hence the qur'an is conveyed and transmitted by way of oral back from prophet Muhammad SAW and confirmed/synchronised with the text.
There are also 4 different levels of speed in reading the qur'an: At tahqiq (very slow and tajweed are read perfectly, this is to teach how to study the Quran), At tarteel (slow and with tajweed, this is the best way to read the qur'an as prescribed in QS.25:32), at tadweer (medium speed with tajweed, normally read by imaam during shalah), and al hadr (fast but still with tajweed).
Apart from these, a good reciter must understand arabic to be able to give emphasis on certain words/sentences, however each qari/qariah are free to have their own styles, some people like certain styles more than the others. For example: there are those who prefer Imaam Sudais more than imaam ghamdi, and the other way round.
As br. woodrow has explained earlier, this is all part of the miracle of the qur'an, how every letter, every word convey specific meanings that cannot be fully translated. Consider this: Is it possible that an illiterate man in the 7th century created the guidelines for the mankind, addressing every aspects of humankind in this world and hereafter, over intermittent periods of 23 years (where no editing was possible), in a literary style that is still the peak of arabic language even today, in a style that is unlike any other literary work in the past 1,400 years, containing predictions that came true and mathematics as well as scientific facts that is impossible to achieve if it were written or created by a mere man, let alone an illiterate one?
Befitting the theme of this thread, you all non-muslims have now heard the message. It is up to you to set aside your arrogance and really dig deep to learn more about Islam with open heart and open mind, because you no longer have an excuse that you have not heard the message of Islam.
So the tonal nature is in itself qualitative, as opposed to gregorian chants which are stylistic (or done to "honor" the spirit moreso than to prove the message).
