Editing Consonant gradation (section)

====Historical sound changes affecting realization of weak grades====

* The weak grades *p̆p, *t̆t, *k̆k of geminates coincided with plain *p, *t, *k.
* The weak grades *mb, *nd, *ŋg of nasal+stop clusters were assimilated to geminate nasals {{IPA|/mm/}}, {{IPA|/nn/}}, {{IPA|/ŋŋ/}} (''ng'').
* The weak grades *lð, *rð of liquid+{{IPA|/t/}} clusters were similarly assimilated to geminate liquids {{IPA|/ll/}}, {{IPA|/rr/}}.
* *β merged with *ʋ (''v''). This may have been lost later. For example, the 3rd person singular suffix *-pi is represented by a [[chroneme]], i.e. a lengthening of the preceding vowel; e.g. *tule-βi 's/he comes' → Old Finnish ''tuleu'' → Modern Finnish ''tulee''.
* Between two unstressed short vowels (i.e. in the weak grade of suffixal gradation), *ð and *h were lost (but not after a diphthong, cf. illative plurals in ''-oihin'', verbs in ''-oida''); these may be preserved in a variety of dialects.
* After a stressed vowel, *ð remained up until the dissolution of the Finnish dialects. It was lost entirely in Eastern Finnish, while Western Finnish dialects have varying reflexes: {{IPA|/ɾ/}} or {{IPA|/r/}} in multiple western dialects, {{IPA|/l/}} in the old Tavastian dialects, {{IPA|/ð/}} in archaic Southwestern and Northwestern dialects. As the area of {{IPA|/ð/}} shrunk throughout the 17th—19th centuries, standard Finnish {{IPA|/d/}} developed as a [[spelling pronunciation]] of orthographical ''d'', modeled after other languages such as Swedish, German and Russian.
* *ɣ also remained until the dissolution of the Finnish dialects. It was generally lost, but in the western dialects it may have become {{IPA|/j/}} (most widely between a liquid and {{IPA|/e/}}, as in ''kylki'', ''järki'' below) or {{IPA|/ʋ/}} (between two close labial vowels, as in ''puku'' below).
* The geminate affricate *cc : *c̆c (found in e.g. *meccä 'forest') was fronted to a dental fricative *θθ : *θ. This sound has been lost in most dialects. Widely in Eastern dialects, both grades became {{IPA|/ht/}}, leading to loss of gradation. Standard Finnish was left with an unalternating {{IPA|/ts/}} (''metsä'' : ''metsän''), a spelling pronunciation similar to the case of {{IPA|/d/}}. Other patterns found include unalternating {{IPA|/tt/}}; alternating {{IPA|/tt/}} : {{IPA|/t/}} (coinciding with original *tt); alternating {{IPA|/ht/}} : {{IPA|/h/}} (in Eastern dialects, coinciding with original *ht); alternating {{IPA|/ht/}} : {{IPA|/t/}}; and alternating {{IPA|/ss/}} ~ {{IPA|/s/}}.

These changes have made qualitative gradation become more complex, especially in the case of ''k''. In standard Finnish, ''k'' is the phoneme with the most possible changes. It can disappear as in ''jalka'' 'foot' → ''jalan'' 'foot-Gen', or:<ref>{{cite web |url= http://www.uta.fi/~km56049/finnish/diabk.html |title= The diabolical k |access-date=2009-01-24 |work= Finnish Grammar |author= Kimberli Mäkäräinen }}</ref> 
{| class="wikitable"  style="text-align:center; margin:auto;"
|- style="background:lightgrey; color:black; border-bottom: 2px solid black;"
! Environment !! Change !! Strong !! Weak 
|-
| ''-uku-'' <br /> ''-yky-'' || ''k''→''v'' || puku <br/> kyky || puvun <br/> kyvyn
|-
| ''-lki-'' <br /> ''-rki-'' || ''k''→''j'' || kylki <br /> järki || kyljen <br /> järjen
|-
| ''-nk-'' <br /> {{IPA|/ŋk/}} || /k/→{{IPA|/ŋ/}} || sänky <br /> {{IPA|/sæŋky/}} || sängyn <br /> {{IPA|/sæŋŋyn/}}
|}
/j/ has been lost in this position in Southeastern Tavastian, Northern Bothnian and Eastern dialects, resulting in ''kurki'' (crane) : ''kuren'' (crane's) instead of the standard form ''kurjen''.

Short ''t'' also has developed more complex gradation due to various assimilations. Patterns include ''t'' : ''d'' (tie'''t'''ää : tie'''d'''än), ''rt'' : ''rr'' (ke'''rt'''oa : ke'''rr'''on), ''lt'' : ''ll'' (pe'''lt'''o : pe'''ll'''on), and ''nt'' ~ ''nn'' (a'''nt'''aa ~ a'''nn'''an).

Alternation patterns for ''p'' include ''p'' : ''v'' (ta'''p'''a : ta'''v'''an) and ''mp'' : ''mm'' (la'''mp'''i : la'''mm'''en).