Notation for sound changes is pretty straight-forward. In it’s most basic form it looks like this:

A > B

Which means that sound A has become sound B. This can be further expanded into a series of sound changes.

A > B > C

So far, this notation means that the sound changes apply regardless of the environment (i.e. always). If we want to represent a specific environment in which the changes apply then the following notation is used:

A > B / C_D

This is read as: Sound A becomes sound B after C and before D. Here the underscore is used to represent the sound being changed.

The empty set symbol (∅) is used to represent deletion or epenthesis depending on its location

A > ∅ / _C ∅ > A / _C

In the first rule, A is deleted before C, in the second one it is added.

Special symbols are used when the environment is not determined by a particular sound but a certain position. For word boundaries the number symbol (#) is used in the following manner:

A > B / _# A > B / #_

Which indicates that the sound changes take place word-finally and word-initially respectively.

The greek letter sigma (σ) is used to indicate syllable, and a bracket with a subscript sigma is used for syllable boundaries.

Other sources state that the percentage symbol (%) is used to represent a syllable and that the dollar sign ($) represents a syllable boundary.

A > B / _σ || A > B / _% A > B / _] σ || A > B / _$

The first example means that the sound change takes place only if it’s followed by a syllable (word-initially or medially). The second example means that the sound change takes place only at the end of a syllable.

In certain cases, the environment might have optional properties, in those cases the environment is enclosed in (parenthesis)

A > B / _(C)D

This means that A becomes B before D, whether or not C is in the way.

If the sound changes affects (or is affected by) a regular set of sounds, distinctive features might be used. I will expand on those on a future post.

A > B / [+continuant, +nasal]_ [+syllabic, +round] > [+syllabic, -round] / C_

The first example states that A becomes B before any nasal consonant. The second example states that any round vowel becomes unrounded after C.

If more than one sound is affected or more than one environment intervenes, then {braces} are used. Sources are fuzzy on this one, at the very least it seems to apply for environments.

A > B / _{C, #}

This means that the change takes place before C or word-finally.

Finally, remember basic IPA notation if you are writing allophonic rules (I also plan to expand on this on the future): /Slashes/ for phonemes and [brackets] for phones.

References

Most links I found point to dead webpages, and the ones that don’t, link to sketchy webpages. Remember people, whenever you find something cool, back it up at the Wayback Machine.