As time went on, national characteristics grew up, especially in the Baroque era. The Italians dared to express the sharpest feelings in music: the French preferred simply to flatter the ear. The Italians used elaborate passaggi to join up the main notes, while the French preferred to polish a single note. The French developed the sweetness of the flute and oboe: while the Italians concentrated all their genius on developing the art of the violin. The Germans imitated the French and the Italians by turn, keeping a clear distinction and even exaggerating the differences: while the English synthesised the best of each, distilling the result into something quite their own.
These differences are hard to capture in writing: but they become rather clear as soon as you hear them and have an idea what you're listening for.
It’s also interesting to note that while the Italians did it, the Germans wrote about it: i.e. the Italians created new freedoms, simply because they felt right, while the Germans tried to systematise the practice of the Italians, giving Greek names to the licences by comparison with the rules of speech: but these hardly do more than catalogue the effects of the different licences after the event. So we have a modern Europe in embryo, where the Italians are busy creating, the French are busy polishing, the Germans are busy systematising what the others do, and the English are busy making a compromise of the whole lot.
I suspect there is a deal of research waiting to be done on which music styles may be most effective when you're learning the languages of Eastern Europe, Asia, African, Polynesia ... There are of course special considerations about memory hooks which western classical music activate in some cultures: as I understand it, the essential factors which determined Lozanov's choice of the Viennese classics for the first concert-reading are
But Lozanov wasn't able to work in all cultures or with all generations: of course Mozart works more-or-less for Finnish and Russian and even for Japanese: but the short experience I had of hearing suggestopedia Japanese with Japanese music certainly gave me a completely different entry into the culture than I had otherwise had.
And while it may seem obvious to avoid music in which voices singing words, don't lets forget that it can have a real value in other parts of a course, as a background to activities, setting atmosphere when people come in and leave the room and so on. Folk music and World Music too, of course.