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Recording control

The subject will be prompted by an automatic system - EUROPEC running on the SESAM workstation positioned outside the anechoic room. The EUROPEC system will be controlled by a recording manager (operator), viewing the standard SESAM monitor. The subject will use a second monitor placed in the anechoic chamber, taking its video input from a ``T'' connection from the SESAM video output. The size and positioning of the monitor will allow the subject to see the prompted text and level meter without stress. The positioning of the monitor with respect to the microphone will ensure that there is no detectable noise pickup, either acoustically or electrically (particularly at line and frame frequencies.) Bochum University suggest that by using EGA or VGA graphics mode the line frequency is above 20kHz and therefore unlikely to be a source of interference.

The speaker to microphone distance, azimuth and elevation will be controlled by ensuring minimal head movement commensurate with minimum subject stress. A headrest is highly recommended.

The subject will have, for the material/country combinations specified in the recording material section, an acoustical prompt generated by a second SESAM fed by the RS232 output of EUROPEC.

The operator will continuously listen to the subject at all times via the recording chain. This will allow subject-operator communication and enable the operator to do a 100% check on the speech material content. Bochum University suggest that 2 operators should be employed simultaneously to reduce fatigue. The headphone output of the PCM/DAT digital audio safety backup machine would be a suitable source for audio monitoring.

The operator will speak to the subject in the anechoic room via a one way intercom/loudspeaker system, which will be switched off during takes. The gain of the intercom system shall be set to a level at the ear representing speech 1 metre from the lips of an average talker. The setting of this level is important as it will tend to effect the speaking level of the subject - and should be consistent across recording sites.

Speaking effort will be controlled for some speaker/material combinations as specified in the reference material section. This will be done by the use of a speech level meter displayed on prompting monitor by EUROPEC. There will be three modes of operation:

  1. The level meter gain set to nominal, after the speaker has stabilised in level the recording gain will be adjusted so that the normal peak level of the speech reaches a reference point, 12 dB below peak. The speaker is controlled for consistent speaking level during the subsequent take by being asked to keep to reference point as much as possible.
  2. The level meter gain is set 6dB lower, the speaker keeps to reference point and so will speak 6dB louder.
  3. The level meter gain is set 6dB higher than nominal, the speaker keeps to the reference point and so will speak 6dB more quietly.

Speaking style will be controlled by:

  1. For some specified material the prompting system will show sets of sentences as a single item, and for other material they will be shown as separate items.
  2. For some country/material combinations the speaker will be additionally prompted by an audio stimulus. The audio will be generated as a result of an RS232 serial output from EUROPEC/SESAM.

Speaking rate will not be controlled except that the maximum rate of presentation of prompted items will be at a rate set within EUROPEC dependent on the material. This rate will be defined within the choice of material section.

There will be no attempt to produce stress in the subject. The total amount of material recorded in each session will be restricted to 8 minutes representing approximately a 30 minute elapsed time session. This limit will minimise stress on the subject and represents the maximum time that can be recorded on a 20 Megabyte disc.

The recording manager will ensure that the subject is in a relaxed condition.

There will be no attempt to control any speaking effect due to the time of day of the session.

next up previous contents index
Next: Recording procedure Up: Recording protocol Previous: Recording mode and prompting

EAGLES SWLG SoftEdition, May 1997. Get the book...