Phonological hierarchy describes a series of increasingly smaller regions of a phonological

Phonology

Phonology is, broadly speaking, the subdiscipline of linguistics concerned with the sounds of language. That is, it is the systematic use of sound to encode meaning in any spoken human language, or the field of linguistics studying this use...

 utterance. From larger to smaller units, it is as follows:

1. Utterance
   Utterance
   In spoken language analysis an utterance is a complete unit of speech. It is generally but not always bounded by silence.It can be represented and delineated in written language in many ways. Note that in such areas of research utterances do not exist in written language, only their representations...
   
   
2. Prosodic declination unit (DU) / intonational phrase (I-phrase)
3. Prosodic intonation unit
   Prosodic unit
   In linguistics, a prosodic unit, often called an intonation unit or intonational phrase, is a segment of speech that occurs with a single prosodic contour...
   
    (IU) / phonological phrase (P-phrase)
4. Prosodic list unit (LU)
5. Clitic
   Clitic
   In morphology and syntax, a clitic is a morpheme that is grammatically independent, but phonologically dependent on another word or phrase. It is pronounced like an affix, but works at the phrase level...
   
    group
6. Phonological word
   Phonological word
   The phonological word or prosodic word is a constituent in the phonological hierarchy higher than the syllable and the foot but lower than intonational phrase and the phonological phrase...
   
    (P-word, ω)
7. Foot (F): "strong-weak" syllable sequences such as English ladder, button, eat it
8. Syllable
   Syllable
   A syllable is a unit of organization for a sequence of speech sounds. For example, the word water is composed of two syllables: wa and ter. A syllable is typically made up of a syllable nucleus with optional initial and final margins .Syllables are often considered the phonological "building...
   
    (σ): e.g. cat (1), ladder (2)
9. Mora
   Mora (linguistics)
   Mora is a unit in phonology that determines syllable weight, which in some languages determines stress or timing. As with many technical linguistic terms, the definition of a mora varies. Perhaps the most succinct working definition was provided by the American linguist James D...
   
    (μ) ("half-syllable")
10. Segment (phoneme
    Phoneme
    In a language or dialect, a phoneme is the smallest segmental unit of sound employed to form meaningful contrasts between utterances....
    
    ): e.g. [k], [æ] and [t] in cat
11. Feature
    Distinctive feature
    In linguistics, a distinctive feature is the most basic unit of phonological structure that may be analyzed in phonological theory.Distinctive features are grouped into categories according to the natural classes of segments they describe: major class features, laryngeal features, manner features,...
    
    

The hierarchy from the mora upwards is technically known as the prosodic

Prosody (linguistics)

In linguistics, prosody is the rhythm, stress, and intonation of speech. Prosody may reflect various features of the speaker or the utterance: the emotional state of the speaker; the form of the utterance ; the presence of irony or sarcasm; emphasis, contrast, and focus; or other elements of...

hierarchy.

There is some disagreement among phonologists on the arrangement and inclusion of units in the hierarchy. For example, the clitic group is not universally recognised, and the P-phrase and IU come from different traditions and have different definitions.