Transformation of live versus recorded speech from the mouth to the open or occluded ear

Abstract

Auditory self‐monitoring studies require the participants’ speech feedback to be manipulated experimentally and then presented to the ear. The acoustic levels of the altered speech must be the same as those under normal speech feedback conditions when speech is transmitted to the ear live, directly from the mouth. Therefore, it is critical to understand the transfer function between the mouth and the eardrum. To further this understanding, live and played‐back self‐generated speech for two female and two male individuals were recorded using a probe tube microphone inserted into the ear canal at a fixed distance from the tragus. The played‐back speech samples were delivered via a B&K artificial mouth, at the sound pressure level calibrated to match the level at the lips. The artificial mouth was placed offset to the participants right side and in line with the x and z axes of his/her mouth position. Recordings were conducted with the ears either open or sealed with ER‐3A insert earphones. In addition, the level and content of speech were systematically varied. The equivalent sound level and long‐term average spectra of the corresponding pairs of speech samples were analyzed as a function of the experimental manipulations.