Department of Special Education and Communication Disorders


Date of this Version



Published in Journal of Voice, Vol. 28, No. 4, pp. 523


© 2014 The Voice Foundation Used by Permission.


Objective. To elucidate capabilities and limitations of the VocaLog, a device marketed to log-calibrated dB sound pressure level (SPL). Study Design. The study design varied depending on the experiment. All were prospective. Some were case series, and others were cohort studies without controls.

Method. Experiments were conducted to determine (1) whether the VocaLog logged phonatory activity and silence when it should, (2) if nonphonatory activities were detected, (3) correlation of VocaLog dB values to an external sound level meter (SLM), and (4) accuracy of phonation time (PT) and speaking time (ST) estimates from the VocaLog.

Results. Silence and phonatory activity were logged as such nearly 100% of the time. Nonphonatory activities were sometimes detected as dB values, including coughs, throat clear, belching, and swallows. The dB values from the VocaLog were strongly correlated with dB SPL from an external SLM. When on the neck, the device rarely picked up external sounds when the external noise was between 85 and 103 dB SPL. The VocaLog gave a reasonable estimate of ST but overestimated PT.

Conclusions. Overall, the VocaLog holds promise as means of indexing vocal loudness via calibrated dBSPL levels. However, some nonphonatory activity is also likely to be logged. The device provides a reasonable estimate of ST, but not PT.