A new reusable eartip for audiometry: An alternative eartip for the KUDUwave insert earphones
In April 2021, a worldwide shortage of 3M™ E-A-RLINK™ foam eartips was reported due to manufacturer production delays – this is still ongoing to date. The KUDUwave audiometer, the only comprehensive diagnostic boothless audiometer, makes use of modified 3M™ E-A-RLINK™ foam eartips. As a result, eMoyo has no supply of KUDUfoam insert eartip products for use with the KUDUwave audiometer (ETA from 3M™ is unclear, as we have already been waiting for more than 2 months for our orders). Due to this, an alternative eartip solution had to be designed, tested, and developed to offer our current and new clients an alternative solution.
One of the challenges that the KUDUwave audiometer offers a solution to, is the inaccessibility of hearing healthcare services due to expensive and bulky equipment, such as a sound booth. The KUDUwave uses Ambi-DomeTM technology, a double attenuation solution (circumaural ear cup and a foam eartip) to provide increased attenuation during audiometric testing. This technology affords the clinician the ability to test outside of a sound booth.
The new reusable KUDUtip is a triple flange eartip designed specifically for pure tone and diagnostic audiometry. The KUDUtip is manufactured with materials that do not adversely affect auditory and general health. In addition, the eartip is manufactured in accordance with EN 352-2. The EN 352-2 standard specifies the design, development, and performance of ear tips. This includes specifications for the sound attenuation of the eartips, which is particularly important for audiometric measurements conducted outside of a sound booth.
The KUDUtip has been designed to provide optimal ambient noise attenuation during audiometry, whilst still being comfortable in the patients’ ear canal. The KUDUtip is a one-size-fit-all eartip, which is easy to insert deeply into the ear canal.
Clinical trials conducted with the new reusable KUDUtip for audiometric measurements, air and bone conduction thresholds obtained using the KUDUfoam (yellow and beige eartips) and those obtained using the new reusable KUDUtip were compared. The KUDUfoam and the new reusable KUDUtip had thresholds within test-retest reliability thresholds of each other across the frequency spectrum. This showed that KUDUwave audiometers using the new reusable KUDUtip can be calibrated in the same fashion as those using the current KUDUfoam. KUDUtips can be used to obtain reliable and accurate air conduction audiometric measurements.
The second important evaluation that was conducted was the ambient noise attenuation (noise reduction) levels of the KUDUtip. The KUDUwave audiometer is mainly used outside of a sound booth; thus, it is important that it attenuates ambient noise sufficiently to allow for screening and diagnostic audiometry outside of a sound booth.
The attenuation levels were determined by using a free-field speaker in an audiometric sound booth, to measure hearing threshold levels on an individual with ears unoccluded versus with the KUDUwave + KUDUtip occluding the ears (Table 1).
Figure 1: Attenuation values in dB HL of the KUDUwave and new reusable KUDUtip (shown by the blue line) and the KUDUwave & KUDUfoam (shown in yellow).
The attenuation levels of both configurations are similar between 125 Hz and 8000 Hz, with the biggest attenuation difference at 4000 Hz of a little more than 10 dB. The ambient noise attenuation levels of the new reusable KUDUtip combined with the KUDUwave circumaural ear cup are significantly high and closely mimic the ambient noise attenuation levels of a 1X1 sound booth. Thus, the ambient noise attenuation of the new KUDUtip with the KUDUwave circumaural cup allows for testing down to 0 dB HL for both screening and diagnostic audiometry outside of a sound booth in a typical open office environment.
The third evaluation that has been performed is the determination of the occlusion effect of the new reusable KUDUtip. The occlusion effect (OE) is the enhancement of bone-conducted signals as a result of occluded ear canals. OE is a well researched and known phenomenon. The magnitude of the OE generally depends on the earphone or headset you use to occlude the ears. It is a well-accepted knowledge that insert earphones with deeper insertion offers smaller OE magnitudes than most audiological headsets.
The below table shows the occlusion effect values when using the new reusable KUDUtip covered with a KUDUwave circumaural headset, determined through psychoacoustic evaluation. The OE values are 13.9 dB at 250 Hz, 8.0 dB at 500 Hz, and 3.0 dB at 1000 Hz. OE values are important to consider when conducting bone conduction audiometry.
The Pros of using the new reusable KUDUtip for audiometric measurement
- High attenuation values to allow for testing outside of a sound booth
- Can be used for both screening and diagnostic purposes
- Reusable and therefore cost-effective, as it is common practice to clean and reuse KUDUtips
- One size fits all
- Easy to insert
- Soft on the ear and comfortable for all patients