In natural speech flow, syllables are often tightly connected, pronunciation is smoother, and sounds feel more coherent. This coherence is not a property of individual characters, but a manifestation of words and phrases within sentences. Liaison (linking) and assimilation mainly occur in speech flow, and are more noticeable in spoken language.

Liaison refers to the natural connection of the pronunciation of two adjacent syllables, where the pause between them shortens or disappears, and the breath continues uninterrupted. Liaison does not change the sounds of the characters themselves, but makes the pronunciation sound smoother. Liaison is most common in phrases, common collocations, and rapid dialogue.

When the ending of an initial consonant connects smoothly to the beginning of the next syllable, the pronunciation can feel tighter. For example, in the word 今天, the n at the end and the t at the start of the next syllable quickly connect, and the flow remains uninterrupted. There should be no deliberate pause after the consonant; this is the basis for natural liaison.

The vowels ending syllables can smoothly transition to the next syllable, especially when the preceding syllable ends with a vowel. The mouth shapes stay connected, airflow continues, and is carried away by the next syllable. This liaison is very evident in phrases like 你好、不要、可以.

In erhua words, the preceding syllable often links with the 'er' sound, and the overall pronunciation becomes tighter. The erhua suffix is not pronounced as a separate sound, but merges with the preceding rhyme to form a smooth segment. In Beijing Mandarin and northern Mandarin, this liaison is especially common.

Assimilation is when neighboring syllables influence each other's pronunciation, causing certain phonemes to become closer or more similar. Assimilation typically occurs in rapid speech as a natural simplification of pronunciation. In Chinese spoken language, assimilation more often appears as subtle sound changes rather than complete replacement.

Nasal assimilation refers to when the meeting of neighboring syllables causes the nasal sound to become more nasal or the place of articulation to become closer. For example, in 很忙, the n and m connect tightly, and the nasal sound of n influences the initial of m. In actual pronunciation, the two sounds stick closer together, sounding more seamless.

Neutral tones frequently appear in liaison and assimilation environments, making the whole word or phrase shorter and lighter. Neutral-tone syllables are easier to link with the preceding and following syllables, forming a smooth prosody. In spoken language, particles like 'de', 'le', 'ba' often undergo neutral tone and link with surrounding syllables.

Liaison and assimilation are most common in: high-frequency word groups, subject–verb phrases, verb–object phrases, and structures with particles. In these environments, the syllables within the internal grammar tend to be tightly connected. A group of words with a complete meaning is typically pronounced as a single 'beat'.

The key to improving liaison and assimilation is to consciously maintain breath and mouth shape continuity within complete sentences. In slow practice, focus on syllable connections; as speed increases, let mouth movements become automatic. The goal is to achieve smooth pronunciation, not forced concatenation of sounds.