Automatic speech recognition using echo cancellation

US4914692A · kind A · utility

Assignee

• AT&T Bell Laboratories · US

Inventors

• Walter T. Hartwell · McLeansboro, US
• Mark A. Johnson · Spicewood, US
• Joseph Picone · Richardson, US

Key dates

• Filing date: Dec 29, 1987
• Grant date: Apr 3, 1990
• Expiry date: Dec 29, 2007

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04M2201/40
• WIPO field: Telecommunications
• WIPO sector: Electrical engineering

Abstract

A customer inquiry unit that allows the recognition of human speech in the presence of an initial prerecorded message transmitted by the customer inquiry unit via a telephone network. The customer inquiry system is designed to be utilized to respond to inquiries received via the telephone network. The system functions by responding to a telephone call received via the network to transmit an initial speech message to the customer. Due to a variety of network problems, a portion of the speech energy of the message is reflected back to the inquiry system. This reflected energy is commonly referred to as an echo. If the customer starts to speak before the inquiry system has finished the initial message, the system utilizes an echo canceler to remove the echo received back from the telephone network and only transfers the speech response to a recognition subsystem. The echo canceler adapts to the telephone network during the initial portion of the initial speech message before the customer can respond.