Ac40 clinical audiometer

The LabView (National Instruments, Austin, TX, USA) environment was used for software development.
For the ripple spectrum test, the digitally synthetized signals were digital-to-analog (D/A) converted by a USB 6212 data acquisition board (National Instruments) and played in a free sound field via an SP 90 loudspeaker (Interacoustics, Middelfart, Denmark) located at a distance of 1 m in front of the CI user.
For the speech discrimination test, signals were played with an AC-40 clinical audiometer (Interacoustics, Denmark) and SP 90 loudspeaker (Interacoustics, Denmark) located at a distance of 1 m in front of CI user. The average sound level of the signals was 65 dB SPL in the clinical test.
The training proceeded at CI users’ home using their PC, and digitally synthetized signals were D/A converted by the sound card of PC. During the training, the CI users could use a comfortable sound level by their choice.

To assess the effect of the trial intervention, a complete audiologic evaluation was conducted before chemoradiation therapy and repeated 1 month after the end of chemoradiation. Pure tone air conduction audiograms were performed at frequencies ranging from 0.5 to 14 kHz using an AC-40 clinical audiometer (Interacoustics, calibrated yearly, ANSI S3.6–2004 standards) with inserted earphones (ER-3A, for 0.5 to 8 kHz) and with circumaural earphones (Koss R/80, for 9 to 14 kHz). Bone conduction audiograms were also performed for 5 frequencies ranging from 0.5 to 4 kHz. Sound intensity was measured in decibel hearing level (dB HL). In addition, distortion product otoacoustic emissions (DPOAEs) recordings were performed at 6 frequencies ranging from 1 to 6 kHz using an Echoport ILO-292-USB-II (Otodynamics). The day before proceeding to the second or third trans-tympanic injection, a complete unblinded air conduction audiogram was done for safety monitoring and was not kept blind to the ear assignment. The final audiologic evaluation was conducted by an audiologist blinded to the ear assignment and to the trial records. When the second or third trans-tympanic injection was not performed as scheduled, the complete final audiologic evaluation (including bone conduction and DPOAEs) was conducted before the upcoming chemotherapy.

After a clinical otoscopy examination, the patients underwent pure-tone audiometry using an Interacoustics° AC 40 clinical audiometer in a soundproof booth. Air and bone conduction hearing thresholds, in decibel hearing levels (dB HL), were obtained at octave intervals from 250 to 8000 Hz. For each ear, a four-frequency (500 Hz, 1, 2, and 4 kHz) average pure-tone threshold (PTA) was obtained. Tympanometric measurements were taken using an air pressure from −600 to +300 daPa (Interacoustics° AA222).

The hearing tests were conducted in an ear nose and throat (ENT) department during the patients’ stay in the hospital. All tests were performed by one and the same researcher.
All the patients underwent subjective and objective otolaryngological and otoneurological examination, with particular emphasis on the condition of the outer, middle, and inner ear as well as nearby anatomical areas that may affect the state of hearing or the generation of tinnitus (the nose, paranasal sinuses, and nasopharynx).
Hearing tests were performed through PTA (0.125–8 kHz) and HFA (8–16 kHz), using an Interacoustics AC40 clinical audiometer in an audiometric booth. In PTA and HFA, threshold curves were determined in the 0.125–16 kHz frequency range. The next step was to characterize tinnitus in each patient (excluding the group A) in terms of its frequency and intensity. The data collected during the study were analyzed as follows:

hearing impairment was diagnosed based on the results of PTA and HFA;

a sound threshold of 20 dB was considered the limit between normal hearing and hearing impairment.

All measurements were performed in a soundproof booth. TEOAEs were recorded using the ILO92 system (Otodynamics Ltd., London, UK). The Otodynamics 5.6 clinical OAE software was used, and responses were recorded by a standard transducer (Otodynamics Model UGS TEOAE Probe). The probe, comprising a transmitter and a microphone, was fitted to the external auditory meatus with a foam rubber tip. CAS was delivered with a headphone (TDH49) using an AC40 clinical audiometer (Interacoustics, Middlefart, Denmark).