The move follows reports that Samsung Smart TVs collect data from voice communications and even share them with a third party.
In letters Wednesday to Samsung's North America CEO Gregory Lee and LG's U.S. President William Cho, the Democrat from Minnesota asked whether it was necessary for the companies to collect personal communications in order to operate the voice recognition feature.
"If such communications are unnecessarily captured along with voice commands, is it possible to extract that data before transmission to a third party" Franken wrote.
Samsung said in an email it "supports Senator Franken's commitment to consumer privacy and we appreciate the opportunity to respond to his inquiries regarding the voice recognition feature on our Smart TVs." LG did not immediately comment on the letter.
Samsung's privacy policy for its Smart TV came under criticism as it cautioned customers to "please be aware that if your spoken words include personal or other sensitive information, that information will be among the data captured and transmitted to a third party through your use of Voice Recognition."
In his letter to LG, Franken said the company's policy is unclear about whether it shared data with third parties, and about measures taken to protect any data sent. The company's policy states that users should "be aware that if your spoken word includes personal or other sensitive information, such information will be among the Voice Information captured through your use of voice recognition features."
In the wake of the controversy, Samsung said this week the TV will collect interactive voice commands only when the user makes "a specific search request to the Smart TV by clicking the activation button either on the remote control or on your screen and speaking into the microphone on the remote control."
The interactive voice commands are processed by a third-party provider Nuance Communications for speech-to-text analysis, it said.
"You may disable Voice Recognition data collection at any time by visiting the 'settings' menu," Samsung said in the post. "However, this may prevent you from using some of the Voice Recognition features."
Franken, who is a ranking member of the Senate subcommittee on privacy, technology and the law, asked Samsung and LG if they share the voice data with any other third-party providers for any other purpose, and if the companies place any restrictions or exercise any control over "how third parties use, sell, share, retain, or protect voice data."
The Senator also wanted to know if the companies shared or sold data they collected about viewing habits of users to third parties. He also asked the companies if users could opt out from having their viewing habits monitored.
John Ribeiro covers outsourcing and general technology breaking news from India for The IDG News Service. Follow John on Twitter at @Johnribeiro. John's e-mail address is john_ribeiro@idg.com