Celtic languages are well known for their initial consonant mutations.

Consonant mutation is a prominent feature of the Fula language.

Another type of consonant mutation found in the Celtic languages is affection.

In Irish, there are two classes of initial consonant mutations:

The consonant change is part of a regular consonant mutation.

Irish, like all modern Celtic languages, is characterized by its initial consonant mutations.

Serer is one of the Senegambian languages, which are characterized by consonant mutation.

Japanese can undergo some vowel deletion or consonant mutation in relaxed speech.

Initial consonant mutation: The first sound of a Cornish word may change according to grammatical context.

The possessive pronouns cause different initial consonant mutations.

There are consonant mutation effects.

Vietnamese also has other instances of alternations, such as consonant mutations and vowel ablaut.

In Old and Middle Breton, it was extremely rare to write the consonant mutations.

As far as I am aware there are no publications which deal specifically with Cumbric consonant mutations.

Japanese exhibits word medial consonant mutation involving voicing, rendaku, in many compounds.

Southwestern Mande languages and Soninke have initial consonant mutation.

Eclipsis (consonant mutation in the Irish language)

Nias shows consonant mutation at the beginning of nouns and some other classes of words to show grammatical case.

It's possible that the Cumbric rules resembled the Gaelic consonant mutation rules more closely.

Over time, the initial /b/ underwent a consonant mutation to a /g/, resulting in the modern güey.

Consonant mutation is change in a consonant in a word according to its morphological and/or syntactic environment.

(There are also often vowel alternations that are independent of consonant mutation.)

Consonant gradation is a type of consonant mutation, in which consonants alternate between various "grades".

Consonant alternation is commonly known as consonant mutation or consonant gradation.

This explains the rise of grammaticalised initial consonant mutations in modern Celtic languages through the loss of endings.