Electroglottography Lab 7

Electroglottography (EGG) zTransduce impedance changes in the area between the electrodes zSignal not effected by the vowels being produced zTransduces the VOCAL FOLD CONTACT AREA yONLY information about when the vocal folds are in contact- nothing about the open phase (or glottal width)

Electroglottography (EGG) zDemonstrates vocal fold contact area zUseful in understanding aspects of vocal fold vibration- Asses Lx function zNoninvasive, inexpensive, zNo information concerning area of glottal opening, zSmall electrodes on neck; yglottis opens= impedance rises, yglottis closes= impedance falls

zLines between electrodes represent the electrical current traversing through the v.f.’s Electrodes Glottis Vocal fold contact area Electroglottograph electronics EGG

EGG Signal (inverse filtered) zClosing (upward trace); Opening (downward trace) zv.f.’s touch (close) = greater current Airflow EGG MSEC

Glottogram Point of max Closing ClosingOpening Closed Open Width of area of glottis (% of Maximum) Open 1 Cycle (T)

EGG Contact zAs vocal folds open & close during vibration, the signal’s intensity changes zAir = bad conductor (shows v.f. abduction) zTissue= good conductor (little impedance) zThe electrodes sense resistance. zDoes not measure glottal area but the amount of tissue in contact with other tissue.

EGG Contact Area Ventilatory position Open Phase Closed Phase Different degrees of vocal fold contact during closed phase

Interpretation of EGG Waveforms zGraph represents vocal contact area

Graph Interpretation zA flat Segment 1 represents minimal contact of the vocal folds. It shows the period during which the vocal folds are separated, it is during this phase that peak glottal flow occurs zDuring Segment 2 interelctrode impedance falls rapidly, marking the growing contact of the vocal folds zSegment 3 is the period of maximal vocal fold contact. zVocal fold contact is lost during Segment 4 until a minimum is again reached, ending the glottal cycle

Laboratory zPart I: EGG Setup & Electrode Placement: yPlace electrodes on thyroid lamina: Label printout “Thyroid” xSustain /i / yPlace electrodes just below hyoid: Label printout “Subhyoid” xSustain /i / yPlace electrodes on the cricoid : Label printout “Cricoid” xSustain /i / ySummarize effects of electrode placement

Laboratory zPart II: The Lx wave yPlace electrodes on thyroid xAdjust gain on CSL (Channel 2)  Sustain / a /and printout records: **can capture 2 waveforms on each printout from view A & B Comfortable pitch & loudness Somewhat lower pitch & same loudness Somewhat higher pitch & same loudness Comfortable pitch and softer than comfortable loudness Comfortable pitch and greater than comfortable loudness

Laboratory zPart II: The Lx wave (cont.) yFill in table with F 0 ’s from the sample x# of cycles/total time x 1000= F 0 (Hz) xif it looks like 1/2 a cycle count as such (3.5, 5.5 etc.) yFill in the table with open % and contact % yCompare different pitch and loudness levels(amplitude, frequency of waveform and vocal contact time)

Laboratory zPart III: Lx and Vocal Register yUse Figure A: xModal register xPulse xFalsetto yCalculate F 0 of each yCharacteristics of each register

Laboratory zPart IV: Lx and vocal disorder yUse Figure B: yMark any strange characteristics of this waveform yWhat can you say about this waveform in comparison to normal voices?