Precocious Auditory Evoked Potential Recording with Free-Field Stimulus

*Juan Bautista Calero del Castillo, Alberto Guillén Martínez and Francisco García Purriños*

## **Abstract**

The aim of this study is to determine the thresholds of normality in the recording of precocious auditory evoked potentials with free-field stimulation and to compare them with conventional stimulation with insertion headphones. For this purpose, we have carried out a case series study of children with normal hearing stimulated with insertion headphones, who underwent Auditory Brainstem Response (ABR) and Auditory Steady-State Response (ASSR) with free-field stimuli. Fifty-four ears with normal criteria of children between 6 months and 24 months of age were assessed. The latencies found with free-field stimulation in ABR were significantly longer than the latencies with insert earphone stimulation (p<0.05), and no differences were found in the inter-latencies. No significant differences were found in the thresholds of the ASSR response. We conclude that the ABR thresholds obtained in the free-field correspond to the delay due to the distance of the sound source to the eardrum and, therefore, are superimposable, being applicable to patients where it is not possible to stimulate with insert phones.

**Keywords:** auditory evoked potentials, ABR, ASSR, free field
