Establishing criteria for sounds likely to facilitate phonological mergers around them

Question

I know extremely little about the history of sound changes in languages other than English, so that will be the source of my examples. However, I’m asking this question for a more general, cross-linguistic context.

Mentally going through the variety of phonological/phonetic vowel mergers which have occurred in various accents of English, it’s clear that many have been related to the presence of certain consonants.

Some have happened next to the liquid phonemes /l/ and /r/. For example, the MERRY-MARY-MARRY, HURRY-FURRY, FUR-FIR-FERN, CHEER-CHAIR, SQUARE-NURSE, and SIRIUS-SERIOUS mergers precede historic /r/, and the FOOL-FULL, FOOL-FALL (not sure if that's an established term), FILL-FEEL, and HULL-HALL mergers precede historic /l/. Admittedly, some of those may have occurred after the liquids were already vocalized or dropped.

Others occur near nasals. PIN-PEN is very well known, and the weak vowel merger seems especially strong before /n/ as in the keywords chicken and thicken. I think some California speakers have something like a MORPHING-MORPHINE merger. In my accent (GenAm with mild Inland North features), the vowels in "strength" and "thank" sound almost exactly the same as the vowel in "pain," and I find it baffling that most transcriptions for American English show all three as different.

It seems like there must be something special about liquids and nasals that facilitates the spread of vowel mergers. Both are among the more sonorant consonants in English, but I'm not aware of any mergers around /w/ or /j/ (unless you count yod-dropping and coalescence as vowel mergers), which are the most sonorous of all, or /m/, another nasal.

Can a rough hierarchy of sounds likely to facilitate mergers in their phonological environment be produced? Alternatively, are there any distinct criteria that might indicate the likeliness of mergers near a certain phoneme? Examples of mergers in other languages would be helpful.

Please note that I’m NOT asking about what type of sounds are likely to become merged, which is more obvious. Rather, I’m asking about the phones that facilitate mergers for other sounds around them.

Answer 1

Can a rough hierarchy of sounds likely to facilitate mergers in their phonological environment be produced?...I’m asking about the phones that facilitate mergers for other sounds around them.

Perceptual mergers are a function of phonetic context, so no, there is no abstract list of vulnerable sounds though that is far from obvious (it has generally been assumed that certain sounds are more vulnerable), and their are also no lists of abstractly aggressive sound change environments. It is a pairing of certain sounds in some context.

If you want to construct a list, you should assemble the known sound-replacements that have been discovered in the languages of the world, and extract typological generalizations and statistics from this. This is a rather large-order task which nobody undertakes, instead people tend to focus on a particular frequent pattern, and learn more about it (or settle for the observation that this is a common change). Pre-nasal raising is in the realm of long-studied changes (it is a fact about sound change in a number of Indo-European languages). Your current interest seems to be specific, related to the intersection of nasal raising and pre-velar raising.

Generally, we first look at the known history of a particular change. The effect of r is very old, to the point that US dialects do not at all reflect historical vowel quality in fur, fir, fern and mostly do not distinguish Mary, marry, merry. OTOH the raised (non-neutralized) quality of pink, pig is much more regional and modern. Sociolinguists undertake studies of these phenomena and probably can tell you what is currently known about pig-raising and pink-raising over the past 3-4 decades.