Can you improve on speech by yourself?

[DaveAgain]

Which leaves the question: can you improve your pronunciation just by speaking (and listening) without corrections? I don't expect my own pronunciation in other languages to be anywhere nativelike, but I have noticed that it slides imperceptibly towards the sounds I hear when I'm on holiday, so if you listen attentively there must be some kind of effect on your own pronunciation. I just don't travel enough. And knowing something about phonetics, both in general and about the language in question, should make it easier to identify and pick up the relevant features so that you can adopt them.

I went through a book of short stories over a 3? 4? week period, parroting (offline shadowing) the audio phrase by phrase, and my internal voice during silent reading started to sound markedly more French

[PeterMollenburg]

I don't expect my own pronunciation in other languages to be anywhere nativelike, but I have noticed that it slides imperceptibly towards the sounds I hear when I'm on holiday, so if you listen attentively there must be some kind of effect on your own pronunciation. I just don't travel enough.

This definitely happens. Many people probably know of someone having moved to a foreign country and when they hear them speak after that person has been away for an extended period, their native accent begins to sound more like the those from the country the person has moved to. (e.g., Australians moving to London sounding less and less Australian over time and more and more like an English person.)

[Cavesa]

Of course you can. For example my PLIDA C1 and Goethe B2 (both earned through self study) say so.

Any exercise you do out loud contributes. Any audio you repeat after contributes. Any kind of self talk helps. Tons of listening help. And lots of other things.

Really, the nonsense "you only learn to speak by speaking" should stop. It is mostly perpetuated by teachers (because they want to keep earning money of course) and also by people failing to speak because they haven't learnt the basic grammar and vocabulary. It is very often not the lack of practice, which is to blame.

Sure, it is awesome to have tons of practice opportunities and speaking teaching. But it is not necessary. Lack of such opportunities (for any reason, such as your budget, time, etc) should not be an excuse to give up.