Why do old movies sound like old movies?

One of the biggest differences between older films and more modern ones is the changing nature of acting over the years.

The further back you go in the history of film, the more you'll find movie acting merging with stage acting: Big movements, bombastic delivery, exaggerated facial expressions.

As acting on film began adapting to the medium (the ability to have close-ups, etc), the medium itself adapting and developing (camera work becoming more agile; initially cameras stayed further back and were often stationary, really doing nothing more than framing films like stage plays) and with the introduction of things like The Method, people were able to develop a much more subtle, intimate and nuanced acting style. One of my favourite films is the Coens' The Man Who Wasn't There (2001). Not only does the camera spend much of the movie trained on Billy Bob Thornton's face - so much of his work in that film involves subtle, almost imperceptible changes in facial expressions and eye movements - it's really a good example of something that couldn't and wouldn't have been done that way many decades ago.

I recently watched an old Hitchcock film starring a young Paul Newman (Torn Curtain, 1966). He stood out from other cast members on that movie as he was already developing a much more "modern" acting style. It was a good exercise in the contrast.

Regarding sound effects: early on, American and British film and TV were very similar, but America soon started using a much more developed system of foley which the British didn't bother with for some time. Even today, American film and TV have a much more complete foley approach (having created the role of foley artist, based in the work of Jack Foley). Extensive foley work gives a much greater control over the sound of final product, just as post production effects give control over the image.

Along the way, you notice the refining of the foley presence and process (just as you do with post-production effects); it's much more heavy-handed before it settled down into a streamlined and nuanced process. You can read about the origins of foley here, and the more general history of its development here.

As for speech in film, you'll notice changes over time: there is the speed of their speech. In early periods of film, the cultural perception was that rapid delivery evinced certainty and confidence, and as an extra bonus, a lot of speech covered up lacks in sound effects or the presence of too much background noise (dialogue was harder to isolate with older technology).

And as others have said, the accent often used in earlier American films is the Mid-Atlantic or Trans-Atlantic accent, which was "a consciously learned blend of American English and British English, intended to favor neither." While this attempt to use an accent acceptable to either the British or American ear has fallen by the wayside in favour of the actual American vernacular, the tendency still exists in a small way, like when Canadians adjust their accent to sound neither specifically Canadian nor American, or when actors from my part of the world adjust how they speak to sound neither distinctly like an Australian or a New Zealander, for example.

The accent you are describing is known as the Mid-Atlantic dialect.

Here are a couple articles on the matter: #1, #2, #3

I find it odd that three articles have been written on this subject matter, by the magazine The Atlantic and in couple year time span no less.

But as sure as it sounds odd to us, contemporary films will sound odd to future generations.

The dialect you reference, the mid-atlantic or transatlantic dialect https://en.wikipedia.org/wiki/Mid-Atlantic_accent was actually taught to actors during the early years of movie history as film transitioned from silent pictures to the "talkies".

But as time went by, a new era of acting and accents, less apparently studied, more real, and striving to emulate life and its gritty actuality, was ushered in by a school of actors that were departing from the old traditions, including Marlon Brando, James Dean, Montgomery Clift - all Method actors, who were favoring a more vernacular, slangy style.

So during the 40s to 60s we actually encounter a waning of the popularity of this kind of affective speech. (According to the wiki cited above, Bill Labov, a University of Pennsylvania linguist, dates the decline of this mid-atlantic accent to as early as 1941.) Certainly, by the time the 50s roll around, actors are more and more starting to try to adopt a more low key and less melodramatic approach to scene building, playing things off with a decided cool. So the era of 1940 to 1960 was certainly an era of great flux and change in movie acting.

And even if we are to discount all the influence of the Method School in the 50s, it is still hard to lump the period of 40s to 60s into one like era. Yes, theatrical acting dominated movies in their earliest period, but there were always outlier examples that differed from the mainstream: Humphrey Bogart certainly was talking tough years before in Casablanca, even if Ingrid Bergman wasn't. And, furthermore, movies themselves from this span of 40s to 60s can be so different: compare for example 1940 film "The Grapes of Wrath" to the 1952 film "High Noon" to the 1957 film "Bridge on the River Kwai". All totally different styles. Ford's "Grapes of Wrath", though filmed in 1940, doesn't really dilly dally about with the transatlantic accent; it is gritty and slangy before Method Acting made this famous.

So here's what I really think. Yes, there are a ton of those movies with the "dahlings" and "won't you be a dear", and they comprise the fiber of that similar speech you are referencing during this period. But what is even more consistent about sound during this period of time is that movie sound technology, though it was evolving during this time, was still prehistoric compared to the advanced digital sound recording we have today. (Foley editing was around since 1914, during radio years. So it was nothing new.)

It was, in fact, the quality of the recorded sound itself that made everything sound less dimensional. The years of 1945 to 1975 are referred to as the magnetic era of sound recording (http://museumofmagneticsoundrecording.org/Magnetic.html). Analog recordings have tape hiss, and that is a background sound that is consistently there during the period you reference, and was even present to some extent afterwards, regardless of advances in analog recording equipment that came about during the 60s. Yes, some people actually prefer the warm analog sounds of yesteryear. But most ears are attuned to the layering and all the great movie magic that goes into digital sound recording and digital effects supplied by computers today.

It has not much to do with acting or the style of speech. Because you could hear the same sort of sound in the recorded tv announcements, interviews of common people etc. This has to do with the technology used in recording sound. Because of this, there seems to be a distinctive difference in the way things were said. Of course there is a difference in accent, however, it has more to do with the technology used in recording rather than dialect, accent and pronunciation. You get to hear this stark difference in recorded voices of that era in any language