American linguist Charles Hockett specified 12 design features:

Charles Francis Hockett's 13 Design Features of Language
1. Vocal-Auditory Channel: Much of human language is performed using
the vocal tract and auditory channel. Hockett viewed this as an advantage for human primates because it allowed for the ability to participate in other activities while simultaneously communicating through spoken language.
2. Broadcast transmission and directional reception: All human language
can be heard if it is within range of another person’s auditory channel. Additionally, a listener has the ability to determine the source of a sound by binaural direction finding.
3. Rapid Fading (transitoriness): Wave forms of human language dissipate
over time and do not persist. A hearer can only receive specific auditory information at the time it is spoken.
4. Interchangeability: A person has the ability to both speak and hear the
same signal. Anything that a person is able to hear, they have the ability to reprod