Chapter 1 22 attenuation caused by the overlying skin and soft tissues. A significant difference of 5-20db is observed between 1-4 kHZ when comparing softband mounting to percutaneous mounted devices, associated with a SRT improvement of 4- 7 dB which translates into a 20-40% difference in speech understanding [82,83]. However, as these studies utilised different processors for this analysis direct comparison is challenging. A study comparing the same Baha® 5 processor in a matched patient group with single sided deafness concluded that word understanding and phoneme recognition scores at both 62 and 47 dB SPL were significantly worse for the softband group as compared to the percutaneous group by 16%. Furthermore, the greatest deviations were in the high frequencies above 2000 Hz [84]. In mixed hearing losses [85] and in conductive hearing losses [86] less of an improvement was demonstrated. For a conductive loss of <25db, both the passive Baha® Attract and ADHEAR have comparable audiological performance to a softband system without the requirement of pressure. Aided sound field thresholds of 33+/- 6 in Baha® Attract, 32+/-9 ADHEAR and 27+/-6 in softband were reported and, no significant difference in speech understanding in both the quiet (20dB) and in noise (54dB) found [87]. With regards to the superiority of percutaneous verses active transcutaneous, there is ongoing debate of which provides the best rehabilitation option. When comparing the percutaneous Oticon Ponto system to the active transcutaneous Med-EL bone bridge it was found that the Bonebridge® performed slightly better in the mid-frequencies, while the Ponto had superior results for the lowest and the highest frequencies. The PTA4 improvement was 31.0 ± 8.0 dB for Bonebridge®, and 31.5 ± 2.8 dB for the Ponto system. However, there was no statistically significant difference between the two devices. [88] Passive systems provide excellent audiological rehabilitation however limited by the maximal output as compared to percutaneous option. Hol et al 2013 demonstrated that although either option provides audiological benefits, percutaneous options provided better sound field thresholds, speech recognition and speech comprehension combined with a 10 dB higher output [89]. In 2015, M Iseri et al demonstrated poorer transcutaneous audiological outcomes when compared to the percutaneous BAHI due to the indirect connectivity between the processor and implant [90]. These conclusions were again supported in 2019 by Kohan et al who compared average audiological results in (dB) between two different passive transcutaneous devices and the percutaneous Baha® system. Again, this showed the percutaneous Baha® to be better at low and mid frequencies. Interestingly it also compared different versions of the
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