I'm not necessarily convinced by the argument that there is a connection between nationality and vocal sound or production. That said, I've recently been dipping in and out of EMI's wonderful Les Introuvables du Chant Français  and the thing that struck me most was the quality of the tenor singing. Here are tenors that encompass a vast range of repetoire and vocal weights such as Rene Maison, Cesar Vezanni, Georges Thill, Paul Franz, Fernand Ansseau, Jose Luccioni and Edmond Clement.

I suspect it would take a musical sociologist of some distinction to explain this, but why did France produce such wonderful tenors in the period from (roughly) the beginning of recorded sound to the 1950s? Why does it no longer do so?

More generally, this brings me to my wider question: is it simply invidious to compare singers from so long ago and who grew up in very different circumstances, with singers of today? We all know this kind of thing, which is a staple of criticism and always has been ('You think Padmore's Ottavio was good? You've obviously never heard McCormack's definitive recording of 'Il mio tesoro'. 'Brewer's Isolde? Harumph! Listen to Leider'.) But is this kind of comparison ever useful? Or fair? Does this kind of thing in fact prevent opera from being a properly 'modern' art form, keeping instead pickled in a kind of culturally reductive vinegar?   

I'd agree with Reiner - it's interesting that Ernani chooses 1950, the point at which the long-playing gramophone record became a reality.  Although complete recordings of operas had of course been made before then, it was with the LP that opera recording came into its own, and expectations changed accordingly.  I suspect that, as a result, people's first experiences of opera shifted from the theatre (where in the UK for example they might have caught the Carl Rosa on tour) to records.  Is it too fanciful to suggest that opera followed the trend for popular music to become a recorded art form (with some of the effects Reiner described above)?  And that this changed expectations and greatly homogenised performance style and public taste?

(And I wonder whether the number of singers recording - which has certainly declined in recent years as fewer recordings were made - started declining at the same time.  It was one thing - economically - for a singer to set down a few 78 sides - say three or four arias - and quite another to record a recital or a full performance).

Language, as Reiner suggests, is another key issue.  Taking the pre-1950 date, singers were much more likely to perform in their own language - allowing the development of national schools.  Perhaps the decline in French tenors is due to the unfashionable nature of French opera (at least outside France)?

This may be obvious or it may be silly...

I would have thought the vowel sounds of your native language must influence how anyone produces sound.  French vowels are so different from either open Italian, clear but muted German and so on.  If you have been bred to produce all those odd dipthongs, then singing the language will sound effortless.  (I am very fond of France and would not wish to encourage the crude post Thatcher and Bush Francophobia, but it is odd that French is the first foreign language to be taught in Britain - the sounds are very tricky.)