Modal voice is the vocal register used most frequently in speech and singing in most languages. It is also the term used in linguistics for the most common phonation of vowels. The term "modal" refers to the resonant mode of vocal cords; that is, the optimal combination of airflow and glottal tension that yields maximum vibration.

In linguistics, modal voice is the only phonation found in the vowels and other sonorants (consonants such as m, n, l, and r) of most of the languages of the world, though a significant minority contrast modal voice with other phonations. Among obstruents (consonants such as k, g, ch, j, s, and z), it is very common for languages to contrast modal voice with voicelessness, though in English many supposedly voiced obstruents do not have modal voice in most environments.

In speech pathology, the modal register is one of the four identifiable registers within the human voice, lying above the vocal fry register and overlapping the lower part of the falsetto register. This view is also adopted by many vocal pedagogists, although some vocal pedagogists may view vocal registration differently. In singing, the modal register may also overlap part of the whistle register. A well trained singer or speaker can phonate two octaves or more within the modal register with consistent production, beauty of tone, dynamic variation, and vocal freedom. The modal register begins and ends in different places within the human voice. The placement of the modal register within the individual human voice is one of the key determining factors in identifying vocal type.