does high phoneme appearance affect sound change?

[Přemysl]

Is a phoneme with a relatively high frequency (appearance not pitch) more likely to under go sound change? For example, are things like i-affection and u-affection of /a/ more common when a language is /a/ heavy, such as in the Indo-Iranian family where in some languages /e/ /a/ and /o/ all merged into /a/.

[chris_notts]

You could also argue that very low frequency phonemes are more likely to undergo change and merger because their low frequency increases the chance of misperception, and decreases the disadvantages of loss.

[Zaris]

You could also argue that very low frequency phonemes are more likely to undergo change and merger because their low frequency increases the chance of misperception, and decreases the disadvantages of loss.

I agree. Mostly used sounds are less likely to change bc people use them all the time (counter-intuitive from a diachronic standpoint, innit?) while least used sounds are bound to end up merging with other phonemes.

I know in proto-italic short vowels in open syllables were "weakened" to /i/ <amicus> <inimīcus> and weakened to /e/ in closed syllables <factus> <ineptus>

So the tendency appears to be from less used to more used bc I believe /e/ and /i/ were used far more than /o/ and /a/ in PIE.

[Astraios]

<factus> <ineptus>

Isn't ineptus from aptus?

[Zaris]

<factus> <ineptus>

Isn't ineptus from aptus?

Probably is. I was quoting examples from a text so I didn't catch the inconsistency. Ill change it if it's that annoying XD

[Magb]

I would conjecture that high-frequency phonemes are more likely to undergo phonemic splits, while low-frequency phonemes are more likely to undergo mergers.