An environment is all the parts of an utterance that directly surround a given sound.
The environment of a sound may be adjacent sounds, or a break in sound, such as at the beginning or end of a syllable , word or phrase.
(English)
Here is an example of the environment of the sound [Q] in the English word tap:
(Spanish)
Here is an example of the environment of the sound [o] in the Spanish word gato:
(The symbol “#” represents the end of a word.)