National Acoustic Laboratories Library

In-situ audiometry: How close is it to conventional audiometry?

DURISALA, NARESH

In-situ audiometry: How close is it to conventional audiometry?

Technology in the hearing aid industry is ever changing. One of the many features that may improve accuracy of hearing
aid fi ttings and patients ’ satisfaction is the inception of in-situ audiometry, which allows the clinician to measure hearing
thresholds with a hearing aid in the patient ’ s ear. Objective : The present study aimed to investigate the validity of in-situ
audiometry measured with a behind-the-ear hearing aid coupled to a customized earmould relative to conventional thresholds
measured using supra-aural head phones . Study design : A total of 24 ears from 15 participants with varying degrees
of sensorineural hearing loss ranging from moderate to severe, were selected for the study. Pure tone hearing thresholds
and real-ear-to-dial-differences were measured for both conventional and in-situ thresholds across 250 Hz to 6 kHz. Results :
Slight but signifi cant mean differences ( p 0.05, paired t -test) of 3.2 and 3.4dB between conventional and in-situ thresholds
at 2000 and 6000 Hz were found before adding REDD corrections with in-situ thresholds yielding better (lower)
thresholds. Except at 250 Hz in dB HL, individual threshold variability between conventional and in-situ threshold
measurements was within or equal to 10dB for 95% of ears before and after adding REDD corrections. Large interparticipant
variation in measured ear canal SPL was noticed at 250, 500, 4000 and 6000 Hz when measured in-situ compared
to headphones, which was attributed to differences in earmould vent sizes provided for different degrees of hearing
loss at the low frequencies and probe placement in the high frequencies. Conclusion: Overall in-situ audiometry proved to
be valid especially in individuals with symmetrical sensorineural hearing loss. Although there are statistically signifi cant
differences, they are within clinically accepted standards. Furthermore, thresholds measured in ear canal SPL will be more
comparable as any changes in hearing threshold levels in either of the measurements will be refl ected by an inverse change
in measured ear canal SPL during REDD measurements.


sensorineural , ,
, hearing loss
hearing aid
real-ear-to-dial-difference

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