Audiological testing was to be carried out every second week (Baseline and weeks 2, 4, 6, 8, 10 and 12). The total duration was three months or until dropout.
The audiological measures consisted of otoscopy, tympanometry, cerumen
management (if indicated), PTA and DPOAEs. Testing was conducted in the same order for all the participants, with the left ear being tested first. Noise levels were monitored
throughout, and universal infection control was carried out. The details can be seen in Table 5.12
Table 5.12
Audiological Measures and Equipment
Audiological Measures and Equipment
Measure Equipment Rationale Description
Otoscopy Welch Allyn Pocket Otoscope Speculae
An otoscopic examination is performed to evaluate the state of the outer ear, and tympanic membrane for abnormalities and/or infection (Rappaport & Provencal, 2002).
Otoscopy is used to determine the condition of the external auditory meatus and tympanic membrane, to ensure that there were no obstructions in the external canal or conditions that may have influenced additional testing procedures (Rappaport & Provencal, 2002.
The normal otoscopic examination was considered as a visible tympanic membrane, no perforations, cone of light, with no obstructions in the canal (besides for cerumen).
Impacted cerumen can affect the reliability of tympanometry and OAEs (Wilson & Roeser, 1997).
Therefore, the removal of cerumen allowed for a clear external auditory meatus to assist in ensuring further reliable audiometric measures.
Cerumen management for cerumen occlusion of more than 70% was performed via the suctioning procedure.
No participants however required cerumen management.
Tympanometry Tympanometer (Maico Easytymp – supplied by
Amtronix)
Tympanometry evaluates middle ear status through the depiction of tympanic membrane motility as a function of variations in air pressure (Clark, Roeser & Mendrygal, 2007). This test serves as an irreplaceable evaluative tool
The appropriate size nub was chosen, and the test was conducted according to the equipment’s’ procedure manual to ensure accurate outcomes.
Audiological Measures and Equipment
Measure Equipment Rationale Description
representing middle ear functioning (Clark et al., 2007). The presence of middle ear pathologies results in severely diminished OAEs, and more severe cases may also influence the results obtained with ABR testing (Swanepoel et al., 2007), thus affecting the reliability of the OAE measures and air conduction PTA measures.
Normal middle ear status for this study was classified as:
• Type A tympanogram [ECV of 0.2 to 2.0 ml, SC of 0.2 to 1.8 ml; MEP of +50 to -100daPa (Jerger, 1975)
• Type As with a slightly decreased static
compliance, however, not yet flat compliance as with a Type B tympanogram (Martin & Clark, 2003) or a
• Type Ad with slightly increased static compliance.
Distortion
OAEs were measured to obtain objective measures regarding the integrity of the cochlea (Prieve &
Fitzgerald, 2002). Therefore, contributing to the differential diagnosis linked to auditory functioning at this level of the auditory system. They provide obtainable results for a wider range of hearing impairment (Prieve & Fitzgerald, 2002) and offer greater frequency specificity (Prieve & Fitzgerald, 2002).
DPOAEs were measured by placing a probe tip (of the appropriate size) in the patients’ ear canal, presenting the tone into the external ear canal and measuring the distortion response obtained from the cochlea.
The frequencies included: 2 kHz, 4 kHz, 6 kHz, 8 kHz, 10 kHz, 12 kHz
Repeated measures were conducted, and noise levels were monitored throughput to ensure valid responses.
This is an objective test as the participant was not required to respond.
Audiological Measures and Equipment
Measure Equipment Rationale Description
DPOAE testing, prior to and after the treatment with kanamycin/capreomycin allowed the researcher to determine changes in amplitude related to the treatment with these drugs.
Responses were from +20 to -20, where -20 was considered absent.
Selected appropriate SNR was +6 dB (see chapters 6 and 7)
PTA Path Sentiero
supplied by Amtronix Acer Laptop
PTA assesses hearing sensitivity as a function of frequency (Bess & Humes, 2008). This provides insight into the integrity of the auditory system as well as information relating to the symmetry, laterality, degree, and configuration of a patients hearing thresholds (Harrell, 2002).
PTA can include air (AC) and bone conduction. Yet, only AC testing was done, as pure tone bone
conduction (BC) thresholds cannot be done over 4 kHz.
Generally, ototoxicity would begin in the high frequencies, and BC audiometry cannot assist in monitoring this. Bone conduction audiometry is often used to rule out conductive components; however, in this case, tympanometry was used to assist with this.
Although BC would have been ideal, the participants
Frequencies tests included:
0.25, 0.5, 1, 2, 3, 4, 6, 8, 9, 10, 11.2, 12.5, 14 and 16 kHz.
Response Mode: Press Button
A mobile diagnostic audiometer was used so that testing could take place at the participants’ bedside if necessary. This was important, as in the beginning stages when participants were hospitalised and were too sickly to leave their beds, testing could be done at their bedsides.
A laptop was used to transfer the results to an excel spreadsheet for accurate recording, and to be placed in the study file.
Change in hearing loss from baseline was recorded, and the overall hearing thresholds and norms were used to monitor the ototoxicity.
Audiological Measures and Equipment
Measure Equipment Rationale Description
were sick and fatigued quickly, and thus reliable BC results were unlikely to be achieved.
Noise
Noise levels were monitored throughout the testing with a sound level meter.
The sound level meter was placed next to the
participant when conducted DPOAEs and PTA. Noise levels did not exceed 55 dB SPL.
Infection control is essential to prevent the transmission of infection (Franklin& Grady, 2001) and allows for ethical and safe research.
Universal precautions were taken to ensure infection control.