In grammar, the voice (or diathesis) of a verb describes the relationship between the action (or state) that the verb expresses and the participants identified by its arguments (subject, object, etc.). When the subject is the agent or doer of the action, the verb is in the active voice. When the subject is the patient, target or undergoer of the action, the verb is said to be in the passive voice. When the subject both performs and receives the action expressed by the verb, the verb is in the middle voice.

The following pair of examples illustrates the contrast between active and passive voice in English. In sentence (1), the verb form ate is in the active voice, but in sentence (2), the verb form was eaten is in the passive voice. Independent of voice, the cat is the Agent (the doer) of the action of eating in both sentences. The cat ate the mouse. The mouse was eaten by the cat.

In a transformation from an active-voice clause to an equivalent passive-voice construction, the subject and the direct object switch grammatical roles. The direct object gets promoted to subject, and the subject demoted to an (optional) adjunct. In the first example above, the mouse serves as the direct object in the active-voice version, but becomes the subject in the passive version. The subject of the active-voice version, the cat, becomes part of a prepositional phrase in the passive version of the sentence, and can be left out entirely; The mouse was eaten.

Overview History of the concept of voice In the grammar of Ancient Greek, voice was called or , with three subcategories: active ( ) passive ( ) middle ( ).Dionysius Thrax. τέχνη γραμματική (Art of Grammar). ιγ´ περὶ ῥήματος (13. On the verb).

In Latin, two voices were recognized: active () passive ()

Voice contrasts Active voice

The active voice is the most commonly used in many languages and represents the "normal" case, in which the subject of the verb is the agent. In the active voice, the subject of the sentence performs the action or causes the happening denoted by the verb. Sentence (1) is in active voice, as indicated by the verb form saw.

(1) Roger Bigod saw the castles.

Passive voice

The passive voice is employed in a clause whose subject expresses the theme or patient of the verb. That is, it undergoes an action or has its state changed. In the passive voice, the grammatical subject of the verb is the recipient (not the doer) of the action denoted by the verb. In English it serves a variety of functions including focusing on the object, demoting the subject and handling situations where the speaker either wants to suppress information about who the doer of the action is, or in reality does not know their identity, or when the doer is either unimportant or likely to be common knowledge. There are syntactic, semantic, and pragmatic motivations for choosing the passive voice instead of the active.Zúñiga, F., & Kittilä, S. (2019). Grammatical voice. Cambridge: Cambridge University Press. Some languages, such as English and Spanish, use a periphrastic passive voice; that is, it is not a single word form, but rather a construction making use of other word forms. Specifically, it is made up of a form of the auxiliary verb to be and a past participle of the main verb which carries the lexical content of the predicate. In other languages, such as Latin, the passive voice for some tenses is simply marked on the verb by inflection: "He reads the book"; "The book is read".

Passives mark this voice in English syntactically as well, which often involves subject–object inversion and the use of 'by'. Sentence (2) is an example of passive voice, where something (the castles) has been (notionally) acted upon by someone (Roger Bigod).

(2) The castles were seen by Roger Bigod.

Antipassive voice

The antipassive voice deletes or demotes the object of transitive verbs, and promotes the actor to an intransitive subject. This voice is very common among ergative–absolutive languages (which may feature passive voices as well), but also occurs among nominative–accusative languages.

Middle voice

Some languages (such as Albanian, Bengali, Fula, Tamil, Sanskrit, Icelandic, Swedish and Ancient Greek) have a middle voice, which is a set of inflections or constructions which is to some extent different from both the active and passive voices.

The subject of such middle voice is like the subject of active voice as well as the subject of passive voice, in that it performs an action, and is also affected by that action. Another difference between middle voice and the other two grammatical voices is that there are middle marked verbs for which no corresponding active verb form exists. In some cases, the middle voice is any grammatical option where the subject of a material process cannot be categorized as either an actor (someone doing something) or a goal (that at which the actor aims their work). For example, while the passive voice expresses a medium (goal) being affected by an external agent (actor) as in sentence (4), the middle voice expresses a medium undergoing change without any external agent as in sentence (5). In English, though the inflection for middle voice and active voice are the same for these cases, they differ in whether or not they permit the expression of the Agent argument in an oblique by-phrase PP: thus while the by-phrase is possible with passive voice as in sentence (6), it is not possible with middle voice, as shown by the ill-formed sentence (7).

(4) The casserole was cooked in the oven (passive voice)

(5) The casserole cooked in the oven (middle voice)

(6) The casserole was cooked in the oven by Lucy (passive voice)

(7) *The casserole cooked in the oven by Lucy (by-phrase ungrammatical when used with middle voice; asterisk (*) indicates ungrammaticality)

In Classical Greek, the middle voice is often used for material processes where the subject is both the actor (the one doing the action) and the medium (that which is undergoing change) as in "the man got a shave", opposing both active and passive voices where the medium is the goal as in "The barber shaved the man" and "The man got shaved by the barber". Finally, it can occasionally be used in a causative sense, such as "The father causes his son to be set free", or "The father ransoms his son".

In English, there is no verb form for the middle voice, though some uses may be classified by traditional grammarians as middle voice, often resolved via a reflexive pronoun, as in "Fred shaved", which may be expanded to "Fred shaved himself" – contrast with active "Fred shaved John" or passive "John was shaved by Fred". This need not be reflexive, as in "My clothes soaked in detergent overnight.". In English, it is impossible to tell from the morphology whether the verb in Sentence (8) is an active voice unaccusative verb or a middle voice anticausative verb with active morphology.Hale & Keyser 1993 Since middle voice reflexives and dispositional middles are found in English with active morphology by looking at Sentence (9), it can be assumed that at least some middle voice anticausatives with active morphology exist as well.Alexiadou, A., & Doron, E. (2011). The syntactic construction of two non-active Voices: Passive and middle. Journal of Linguistics, 48(1), 1-34

(8) The window broke from the pressure/by itself.

(9) This book sells well.

English used to have a distinct form, called the passival, which was displaced over the early 19th century by the progressive passive and is no longer used in modern English.Mike Vuolo, "The House is Building"? Why you never learned the passival tense, even though it used to be proper English grammar., Slate, May 29, 2012 In the passival, one might say "The house is building.", which may today be rendered instead as "The house is being built." Likewise "The meal is eating.", which is now "The meal is being eaten." The similar "Fred is shaving" and "The meal is cooking" remain grammatical. It is suggested that the progressive passive was popularized by the Romantic poets, and is connected with Bristol usage.Platt and Denison, "The language of the Southey-Coleridge Circle", Language Sciences 2000

Many deponent verbs in Latin (i.e., verbs passive in form but active in meaning) are descendants of the Proto-Indo-European middle voice.Sihler, Andrew L, "New Comparative Grammar of Greek and Latin", 1995, Oxford University Press

Other voice contrasts Some languages have even more grammatical voices. For example, Classical Mongolian features five voices: active, passive, causative, reciprocal, and cooperative.

There are also constructions in some languages that appear to change the valence of a verb, but in fact do not. So called hierarchical or inversion languages are of this sort. Their agreement system will be sensitive to an external person or animacy hierarchy (or a combination of both): 1 > 2 > 3 or Anim > Inan and so forth. E.g., in Meskwaki (an Algonquian language), verbs inflect for both subject and object, but agreement markers do not have inherent values for these. Rather, a third marker, the direct or inverse marker, indicates the proper interpretation:

Some scholars (notably Rhodes) have analyzed this as a kind of obligatory passivization dependent on animacy, while others have claimed it is not a voice at all, but rather see inversion as another type of alignment, parallel to nominative–accusative, ergative–absolutive, split-S, and fluid-S alignments.

Voices in topic-prominent languages

Chinese In general, the grammar of standard Chinese (both including Mandarin and Cantonese) shares many features with other varieties of Chinese. However, there are still some differences between the different varieties.

Mandarin

Active voice in Mandarin Mandarin active voice sentences have the same verb phrase structure as English active voice sentences. There is a common active construction in Mandarin called Ba(把) construction:

“Ba” is a coverb, not a preposition. It is a three-place predicate that subcategorizes for a subject, an object, and a VP complement.Her, O. (2009). Unifying the long passive and the short passive: On the bei construction in taiwan mandarin. Language and Linguistics (Taipei), 10(3), 421-470.

This Ba construction is also a direct opposition of active voice in passive voice in Mandarin (i.e. Ba construction (= active voice) vs. Bei construction (= passive voice)).

The following sentence b) is in contrast to sentence a).

(Both a) and b) are adapted from Her, O. (2009))

Passive voice in Mandarin

Topic-prominent languages like Mandarin tend not to employ the passive voice as frequently. In general, Mandarin used to be best analyzed using middle voice, but Mandarin-speakers can construct a passive voice by using the coverb (bèi) and rearranging the usual word order.Li, Charles N.; Thompson, Sandra A. (1981). Mandarin Chinese: A Functional Reference Grammar. Berkeley: University of California Press. For example, this sentence using active voice:

(The first line is in Traditional Chinese while the second is Simplified Chinese)

corresponds to the following sentence using passive voice. The agent phrase is optional.

In addition, through the addition of the auxiliary verb "to be" (shì) the passive voice is frequently used to emphasize the identity of the actor. This example places emphasis on the dog, presumably as opposed to some other animal:

Mandarin also has an object-retaining passive which contains both the object and the topic (mostly the possessor of the object):