At the behest of the Phonetics, a phoneme will be each of the minimum phonological units that in a language are opposed to others generating a significant contrast. For example the phoneme s is opposed to the phoneme n, allowing us to distinguish the word grief from the word pesa.
Meanwhile, the phoneme is also the minimum unit of oral language, because it is a speech sound that makes it possible to differentiate between the many words of a language, for example the phonemes s and t in coso and como; o s and c in single and tail.
The words mentioned above: coso / como, sola / cola, pena / pesa, have totally different meanings, although the pronunciation of each pair hardly differs in the aforementioned sounds. Meanwhile, structurally speaking, the phoneme belongs to the field of language, while sound belongs to the field of speech.
The sounds of each of the words are called allophones. The same phoneme may have different allophones, as it happens with gases and people. Other very common situations are also that the letters match or that the letters sound like more phonemes, for example, c sounds like k and s like z.
Phonemes are not sounds as a physical entity, but rather they are formal abstractions or psychological traces that remain in the sounds of speech.
It should also be noted that phone and phoneme are not the same, because the phone or sound It is characterized by a series of phonetic and articulatory features, the identification of which is the exclusive task of Phonetics. Therefore, the phone will be any of the possible acoustic realizations of a phoneme.
So, in summary, the phoneme will be the phonological unit differentiating (Each phoneme is delimited within the system by the qualities that distinguish it from the others and also by its own significant intention), abstract (because in reality the phoneme is not a sound but an ideal type of sound) e linearly indivisible (It cannot be broken down into smaller units).
On the other hand, we also call phonemes each of the simple sounds of spoken language.
