The word phonology comes from the Greek root phonos which means “sound”, and “logo” which is translated as “study”, this means that phonology is the study of sounds. Phonology is a branch of linguistics that studies and describes the sound or allophone of a language, it is also studies how each of the articulations of the speech organs should be used so that the sounds can be said in an appropriate way according to their accent or intonation.

In phonology, the phoneme (letters) or small meaningless units are identified that represent the minimum phonological units that help us to differentiate one sound from another, such as “can” and “pata”, we must never confuse phoneme with sound, due to since one is a mental image and the other is a material manifestation of the phoneme; Phonemes can be classified according to: the place of articulation, the nasal cavity, the oral cavity and the vocal cords.

Taking into account the point of articulation we find the following phonemes: bilabial, labio-dental, interdental, dental, alveolar, palatal, velar. The mode of articulation or way of expelling the air: stops, fricatives, affricates, laterals and vibrating. The intervention of the vocal cords: deaf or voiced.

Each language contains its own phonological system, in the case of the Spanish language it is made up of 24 consonants; five vowel phonemes and 19 consonant phonemes. Vowel phonemes are those that do not find any kind of obstacles in the oral cavity when the sound is represented and in the case of consonant phonemes they find some kind of obstacle when executing the sound.