Is a statement made in the presence of a party to an action 'not essential' in the context of an action?

is not essential.' [Citation.] 'When a person makes a statement in the presence of a party to an action under circumstances that would normally call for a response if the statement were untrue, the statement is admissible for the limited purpose of showing the party's reaction to it. [Citations.] His silence, evasion, or equivocation may be considered as a tacit admission of the statements made in his presence.' [Citation.]" (People v. Riel (2000) 22 Cal.4th 1153, 1189.)