File:  callinfo.txt
-------------------

Explanation of the audit information provided in "callinfo.tbl"

The file "callinfo.tbl" contains the information produced by manual
auditing of the Switchboard-2 Phase III conversations.  The auditing
process was set up to accomplish two things: (a) provide information
about the speaker and (b) provide information about the channel
quality for the conversation.

The table file contains a single line for each side of a conversation
with comma separated fields to provide the following information:

Field 1 = call ID
Field 2 = date
Field 3 = participant PIN
Field 4 = channel
Field 5 = echo/crosstalk
Field 6 = background noise
Field 7 = distortion
Field 8 = empty
Field 9 = comments

The information on echo (echo or crosstalk in the telephone circuit
refers to the audibility of the channel A speaker in channel B and
vice-versa), background noise (refers to the amount of sounds not made
by the speakers, e.g. baby crying, television, radio, etc.),
distortion (refers to echo and other types of recording problems) and
empty (duration of call) should be interpreted as follows:

- for echo, background noise and distortion:
    0 = none
    1 = discernible
    2 = moderate
    3 = excessive 

- auditor comments (e.g. "cordless_phone", "television", "static",
  "phone_hum")

Calls which showed excessive levels of noise, distortion or echo were
excluded from publication.  All attributes are thus rated on a scale
of 0 to 2, where 0 always refers to optimal channel/call conditions
and 2 refers to the least optimal, but still usable channel
conditions.

An automatic echo-cancelation process was applied to all waveform
files after the auditing was done, so non-zero values "echo/crosstalk"
judgment in the callinfo.tbl do not actually represent the published
quality of the waveform files.