Disclosed is a method of receiving an audio stream containing user speech from a first device, generating text based on the user speech, identifying a key phrase in the text, receiving from an advertiser an advertisement related to the identified key phrase, and displaying the advertisement. The method can include receiving from an advertiser a set of rules associated with the advertisement and displaying the advertisement in accordance with the associated set of rules. The method can display the advertisement on one or both of a first device and a second device. A central server can generate text based on the speech. A key phrase in the text can be identified based on a confidence score threshold. The advertisement can be displayed after the audio stream terminates.