Switchboard Cellular Part 1 Audio

Item Name: Switchboard Cellular Part 1 Audio
Author(s): David Graff, Kevin Walker, David Miller
LDC Catalog No.: LDC2001S13
ISBN: 1-58563-213-9
ISLRN: 775-985-659-424-7
DOI: https://doi.org/10.35111/a74g-hy08
Member Year(s): 2001
DCMI Type(s): Sound
Sample Type: 2-channel ulaw
Sample Rate: 8000
Data Source(s): telephone conversations
Application(s): speaker identification
Language(s): English
Language ID(s): eng
License(s): LDC User Agreement for Non-Members
Online Documentation: LDC2001S13 Documents
Licensing Instructions: Subscription & Standard Members, and Non-Members
Citation: Graff, David, Kevin Walker, and David Miller. Switchboard Cellular Part 1 Audio LDC2001S13. Web Download. Philadelphia: Linguistic Data Consortium, 2001.
Related Works: View


Switchboard Cellular Part 1 Audio was developed by the Linguistic Data Consortium (LDC) and consists of approximately 109 hours of English telephone conversations collected by LDC between 1999-2000. The Switchboard cellular collection focused primarily on GSM cellular phone technology. The project's goal was to target 190 subjects balanced by gender and under varied environmental conditions to participate in (10+) five to six minute conversations on GSM cellular phones. The speech data was collected for research, development, and evaluation of automatic systems for speech-to-text conversion, talker identification, language identification and speech signal detection purposes.

During the study period, LDC collected a total of 1,309 calls, or 2,618 sides (1,957 GSM), from 254 participants (129 male speakers, 125 female speakers) under varied environmental conditions.


This release contains speech data files with documentation describing speaker information (sex, age, education, city and state where raised), call information (date, time, call duration, Personal Identification Numbers, topic) and audit information (channel quality, background noise). The data files are not compressed. The documentation also contains reports on clipped files.

Each speech file consists of a 1,024-byte ASCII-formatted Sphere header, followed by two-channel interleaved mu-law sample data. The mu-law samples represent the actual digital data transmission from the telephone service provider (MCI), as captured separately for each side of the telephone conversation by LDC's telephone collection platform. The header also indicates the caller_pin, callee_pin, topic_id, cellular service/handset information and speaker demographic information.

Other releases in this series include:

Switchboard Cellular Part 1 Transcribed Audio (LDC2001S15)

Switchboard Cellular Part 1 Transcription (LDC2001T14)

Switchboard Cellular Part 2 Audio (LDC2004S07)


Please examine this example audio file to review a sample of this corpus.


55 missing sphere files were added the corpus on August 29, 2012. All copies ordered after that date will include those files. 

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