Introduction

Fisher English Training Part 2 Speech represents the second half of a collection of conversational telephone speech (CTS) that was created at the LDC during 2003. It contains 5,849 audio files, each one containing a full conversation of up to ten minutes. Additional information regarding the speakers involved, and types of telephones used, can be found in the companion text corpus of transcripts, Fisher English Training Part 2, Transcripts (LDC2005T19).

The Fisher telephone conversation collection protocol was created at LDC to address a critical need of developers trying to build robust automatic speech recognition (ASR) systems. Previous collection protocols, such as CALLFRIEND and Switchboard-II and the resulting corpora, have been adapted for ASR research but were in fact developed for language and speaker identification respectively. Although the CALLHOME protocol and corpora were developed to support ASR technology, they feature small numbers of speakers making telephone calls of relatively long duration with narrow vocabulary across the collection. CALLHOME conversations are challengingly natural and intimate. Under the Fisher protocol, a very large number of participants each make a few calls of short duration speaking to other participants, whom they typically do not know, about assigned topics. This maximizes inter-speaker variation and vocabulary breadth although it also increases formality.

Previous protocols such as CALLHOME, CALLFRIEND and Switchboard relied upon participant activity to drive the collection. Fisher is unique in being platform driven rather than participant driven. Participants who wish to initiate a call may do so; however the collection platform initiates the majority of calls. Participants need only answer their phones at the times they specified when registering for the study.

To encourage a broad range of vocabulary, Fisher participants are asked to speak on an assigned topic which is selected at random from a list, which changes every 24 hours and which is assigned to all subjects paired on that day. Some topics are inherited or refined from previous Switchboard studies while others were developed specifically for the Fisher protocol.

Data

The first half of the collection (Fisher English Training Speech Part 1) was released by the LDC in 2004 (LDC2004S13 for speech data, LDC2004T19 for transcripts). Taken as a whole, the two parts comprise 11,699 recorded telephone conversations.

The individual audio files are presented in NIST SPHERE format, and contain two-channel mu-law sample data; "shorten" compression has been applied to all files.

Data collection and transcription were sponsored by DARPA and the U.S. Department of Defense, as part of the EARS project for research and development in automatic speech recognition.

Samples

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