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
Member Year(s): 2001
DCMI Type(s): Sound
Sample Type: 2-channel ulaw
Sample Rate: 8000
Data Source(s): telephone conversations
Project(s): SID, GALE, EARS
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.


The Switchboard Cellular Part 1 collection focused primarily on GSM cellular phone technology. The collection commenced 11/12/1999 and was completed on 05/15/2000. 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.

The Switchboard Cellular Phase 1 Audio produced by the Linguistic Data Consortium, catalog number LDC2001S13 and ISBN number 1-58563-213-9. This release contains speech data files ONLY, along 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.


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

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 the LDC's telephone collection platform. The header also indicates the caller_pin, callee_pin, topic_id, cellular service/handset information and speaker demographic information.

The documentation also contains reports on clipped files.

There are a total of 1,309 files, for a rough total of 109 hours of audio data, 6,545 Mbytes.


55 missing sphere files were added on August 29, 2012. All copies ordered after this date will come complete. Contact ldc@ldc.upenn.edu with any questions.

Available Media

View Fees

Extra Copy
Login for the applicable fee