If diacritics cause duplication in IPA

Question

So in first learning the IPA I went through the consonants and the vowels. This is confusing because in the consonants chart you see stuff like [d̪] or [ʎ̥˔]. At first I thought these were just some extra consonants. But then I saw in some different phonologies such as this, symbols like [pʰ] or even [ɡ̊eːˀ].

Then I ran into the X-SAMPA diacritics, which helped explain what was going on.

_"    ̈ centralized
_+    ̟ advanced
_-    ̠ retracted
_/    ̌ rising tone
_0    ̥ voiceless
_<      implosive (IPA uses separate symbols for implosives)
=     ̩ syllabic
_>    ʼ ejective
_?\   ˤ pharyngealized
_\    ̂   falling tone
_^    ̯ non-syllabic
_}   ̚  no audible release
`     ˞ rhotacization in vowels, retroflexion in consonants (IPA uses separate symbols for consonants, see t` for an example)
~     ̃ nasalization
_A    ̘ advanced tongue root
_a    ̺ apical
_B    ̏ extra low tone
_B_L  ᷅  low rising tone
_c    ̜ less rounded
_d    ̪ dental
_e    ̴ velarized or pharyngealized; also see 5
<F>   ↘ global fall
_F    ̂ falling tone
_G    ˠ velarized
_H    ́ high tone
_H_T  ᷄  high rising tone
_h    ʰ aspirated
_j    ʲ palatalized
_k    ̰ creaky voice
_L    ̀ low tone
_l    ˡ lateral release
_M    ̄ mid tone
_m    ̻ laminal
_N    ̼ linguolabial
_n    ⁿ nasal release
_O    ̹ more rounded
_o    ̞ lowered
_q    ̙ retracted tongue root
<R>   ↗ global rise
_R    ̌ rising tone
_R_F  ᷈  rising falling tone
_r    ̝ raised
_T    ̋ extra high tone
_t    ̤ breathy voice
_v    ̬ voiced
_w    ʷ labialized
_X    ̆ extra-short
_x    ̽ mid-centralized

I have seen some of those other ones around like [ˠ], [ ̪], [ ̟], [ˤ], and [ʷ], but I haven't seen many of the others.

I am wondering (a) where I can learn about each of these symbols in more depth (perhaps some encyclopedia about IPA diacritics, Wikipedia only has links to some of them), and (b), if these are somewhat repetitive in certain cases. That is, it seems that, for example, [ɱ] is a labiodental thing, but you could also do [m̪]. Same with "velarized" things (ˠ), it seems to me those are already covered by the velar consonants like [ŋ] or the similar looking [ɣ]. For example, doesn't seem like you'd ever do [ɣˠ], but here you see [bˠ], even [ɾˠ]. (Interested to learn what all these symbols mean). Same for pharyngealized (ˤ), implosive (IPA uses separate symbols for this), etc. Some pharyngealized ones are found here or here, such as [dˤ] or [ðˤ]. Labialization is found here, such as [gʷ], not sure what that means (hoping some aggregated resource has all this somewhere). For the voiceless stuff ( ̥), the IPA had a few consonants listed in the chart, such as [ʎ̥˔], so seems a bit duplicated (not sure if the meaning is the same). In addition, they already have symbols for a whole range of voiceless consonants (ɸ, f, θ, s, etc.), so seems like duplication as well. Wondering if these "super/subscripts" like [ˠ] or [ ̥] are used for some specific purpose that is required outside of these voiceless/velarized/etc. symbols in the consonant chart. Perhaps it was a later invention. The rest of these symbols I haven't really seen, so not sure what their status or use is.

So basically just wondering where I can learn about all of these things, and if this duplication I am pointing out is real or I am missing something.

Answer 1

The official IPA chart does label what every diacritic means.

Wikipedia also has a thorough description of the IPA, and has a table which links to explanations of almost all the diacritics. The few that aren't, like the voiceless dental fricative release, are pretty self explanatory (especially as you can compare to the nasal release, which does have an article explaining it).

There is redundancy in the IPA. Because there are diacritics for voiced and voiceless there's technically no need to have separate voiced and unvoiced letters. But that would be so ugly and cumbersome. Just like in language itself, redundancy is not a problem.

I think the way most linguists take advantage of the redundancy is to try to use a plain symbol without diacritics for a base phoneme and its most common realisation. For allophones it makes sense to then add modifying diacritics where possible. But there are some languages where the phonemes can only be distinguished by diacritics. People debate about extensions to the IPA to add more symbols for some of those situations. Or some will introduce their own custom symbols, or borrow another IPA symbol for their language, which can be confusing, but that's why you always read their nomenclature first.