Latin pronunciation, both in the classical and post-classical age, has varied across different regions and different eras. As the respective languages have undergone sound changes, the changes have often applied to the pronunciation of Latin as well.
Latin still in use today is more often pronounced according to context, rather than geography. For a century, Italianate (perhaps more properly, modern Roman) Latin has been the official pronunciation of the Catholic Church due to the centrality of Italy and Italian, and this is the default of many singers and choirs. In the interest of Historically informed performance some singers of Medieval, Renaissance and Baroque music adopt the pronunciation of the composer's period and region. While in Western university classics departments the reconstructed classical pronunciation has been general since around 1945, in the Anglo-American legal professions the older style of academic Latin survives to this day.
The following table shows the main differences between different regions with the International Phonetic Alphabet. This is far from a complete listing and lacks the local variations exhibited through centuries, but should give an outline of main characteristics of different regions.
In ecclesiastical use, these regional varieties were, and to a great extent still are, in use, although the Italian model is increasingly advocated and usually followed even for speakers of English, sometimes with slight variations. The official version is that given in the Liber Usualis. This book prescribes a silent "h", except in the two words "mihi" and "nihil", which are pronounced /miki/ and /nikil/ (this is not universally followed). Some English singers choose to pronounce "h" as /h/ for extra clarity.