A comparison of different methods to measure the EGG contact quotient

Abstract

The results from six published electroglottographic (EGG-based) methods for calculating the EGG contact quotient (CQ_EGG) were compared to closed quotients derived from simultaneous videokymographic imaging (CQ_KYM). Two trained male singers phonated in falsetto and in chest register, with two degrees of adduction in both registers. The maximum difference between methods in the CQ_EGG was 0.3 (out of 1.0). The CQ_EGG was generally lower than the CQ_KYM. Within subjects, the CQ_EGG co-varied with the CQkym, but with changing offsets depending on method. The CQ_EGG cannot be calculated for falsetto phonation with little adduction, since there is no complete glottal closure. Basic criterion-level methods with thresholds of 0.2 or 0.25 gave the best match to the CQ_KYM data. The results suggest that contacting and de-contacting in the EGG might not refer to the same physical events as do the beginning and cessation of airflow.

• Closed quotient
• electroglottography
• videokymography