What are variations in the sounds of speech called?

Variations in the sounds of speech are referred to as allophones. Allophones are different phonetic realizations of a single phoneme that do not change the meaning of a word. For example, the way the initial sounds in "top" and "stop" are produced can vary slightly based on their phonetic context, but they still represent the same underlying phoneme /t/. This concept allows for varying pronunciations in different dialects or environments while maintaining intelligibility among speakers.

In contrast, phones denote the actual sounds produced, which can be more general and do not necessarily encompass the idea of meaning or phonemic distinction. Consonants are a category of speech sounds but do not account for the variations in their pronunciation. Phonemes are the mental representations of sounds that distinguish meaning in a language but do not directly address the variations in speech sounds. Therefore, the term allophones specifically captures the essence of the question regarding variations in speech sounds.