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The electroglottograph, or EGG,
is a non-invasive device primarily used to measure vocal fold contact.
It does this by applying a small, high frequency current to a pair
of electrodes and measuring the conductance. The electrodes are held
on either side of the laryngeal area by means of a velcro collar. The
EGG signal provides an accurate indication of fundamental frequency,
and can also provide information regarding open quotient and skewing
quotient. These in turn are related to voice quality and efficiency.
The Rothenburg flow mask, named for its
inventor, Martin Rothenburg, is a clear plastic, circumferentially
vented mask with a rubber seal around the perimeter. The mask is contoured
to fit over the subject's mouth and nose, and is manually held in place.
One transducer in the mask measures oral flow; by using inverse filtering
techniques, an estimate of glottal flow can be obtained. A second transducer
is attached to a short tube which extends past the lips into the mouth;
this measures oral pressure during bilabial closure (e.g., the consonant
/p/). These respiratory signals can also be used to determine efficiency
and quality. For additional information regarding the EGG or flow mask,
visit Glottal Enterprises.
The National Center for Voice and Speech is a Division of The Denver Center for the Performing Arts and a Center at The University of Iowa.
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National Center for Voice and Speech, www.ncvs.org