1.4 DISCUSSION
The outcomes from this study are evident to support the use of the
mobile-app based FFCT to screen hearing loss. This digital method of
hearing screening is the pioneer study carried out in a clinical
practice in Malaysia. The limitations of voice test and audiogram can
thus be eliminated. A developmental study conducted on
smartphone-connected hearing devices proved that the usage was higher
than conventional hearing aids.14
FFVT on the other hand can be performed using words, numbers or phrases
to suit the age of patients. A study conducted using certain higher
frequency speech stimuli proved that FFVT is an acceptable hearing
screening in the geriatric population. Phonetically-balanced words or
phrases were included to increase the reproducibility of the testas loss
of hearing at higher frequencies is a feature of
presbycusis.15 A systematic review was conducted to
determine the accuracy of whispered voice test. Though the sensitivity
in four of the adult studies was 90-100%, there was no standardization
of loudness of the whisper among the examiners and no proper spoken
sequence of words. The distance between the examiner and patient also
varied.8 Thus, these factors affect the accuracy and
reproducibility of the test. The effectiveness of FFVT using numbers and
phonetically balanced monosyllabic (PB) words were analysed in a
comparative study. It is revealed that numbers or easily recognizable
words were effortlessly identified and repeated by patients than PB
words. But, the real relationship of hearing threshold and hearing
distance were not very accurate. It was revealed that 42% of patients
who passed FFVT using numbers were found to have hearing loss when
tested using PB words later. This was applicable mainly in patients with
high-frequency hearing loss, such as presbycusis and acoustic
trauma.16
Hearing screening with PTA is the gold standard test. PTA is performed
by trained audiologists with an instrument that creates a standard range
of test stimuli set at premeasured loudness of sound using decibels. The
American Speech-Language-Hearing Association and the American Academy of
Audiology had given recommendations that define screening at 20dB at
frequencies of 1000, 2000 and 4000Hz. Thus, PTA was the gold standard
test in our study that was compared with FFVT and
FFCT.17 PTA serves as a significant apparatus to
determine the type and degree of hearing loss involved in the diagnosis
of various otological-related diseases. PTA plays key role in helping
clinicians with surgical decisions and to monitor treatment progress.
However, the audiogram is a relatively old method to screen hearing, and
it has only advanced minimally over the past
decades.18 The limited audiology facilities and
expertise are its drawbacks too. PTA is usually not available in the
general practice or district hospitals. A long waiting time is almost
always experienced by patients to have their hearing screened by
audiologists, thus, causing more delays in treatment and rehabilitation
services.
There are various hearing-related mobile-based apps available online.
However, there is no hearing app found so far which can be incorporated
into our daily otolaryngology practice. Most of the apps are not
validated against PTA and thus rendering them not suitable to be used as
screening tools. During the World Hearing Day in 2019, the World Health
Organization had developed a mobile and web-based software for hearing
screening. The software is known as ‘hear WHO app’. This app was based
on validated digits-in-noise technology. It is useful in monitoring
hearing of people with noise exposure at workplace and avid earphone
users. But, as the app is language-dependent, it demands further
validation and conversion into different languages prior to its
worldwide usage.19 A review was performed by Bright
et.al. in 2016 on smartphone-based hearing apps. About 30 apps were
chosen from Google Play and Apple App Store. These apps were validated
against PTA but, their accuracies varied.20 This
review concluded that more detailed, independent validation studies are
required to further test the accuracy of these apps for clinical
practice. Another review was conducted among army servicemen in India to
compare the sensitivity of FFVT with a free iOS application to detect
hearing loss. It was reported that the hearing check app was more
sensitive than the conventional voice test (98% and
73%).21
We report that in our study FFCT has a more standard way of examination
with constant broadband sounds produced in correspondence to pure tone
average. This differs from FFVT as there was a lack in the
standardization of speech sound levels of the examiners. FFCT is user
friendly as it only requires a mobile phone/tablet with an iOS/Android
operating system to access the app. It is much easier for patients to
acknowledge the sounds produced instead of repeating the spondee words
used in FFVT. This is especially useful in patients with presbycusis and
with language problems. FFCT requires minimal practice before one can
start to operate it. There was no cost involved as our team incorporated
basic programming skills to develop the app. FFCT was able to be
completed faster than FFVT with the average time of 1 minute. FFCT was
shown to be more sensitive than FFVT while, FFVT has a higher
specificity for normal hearing levels. [Table 2] FFCT has numerous
potential uses as it can provide a rapid test to predict hearing loss
and can be easily accessible by medical personnel as the programming
language is open-sourced. It is a suitable tool to screen hearing when
audiograms are not available, especially during night shifts and in
district hospitals. FFCT is a convenient way to monitor treatment
response such as in sudden-onset sensorineural hearing loss. It serves
as a teaching tool and as a beginner’s teaching module for doctors
interested in learning programming subject whereby more health-related
mobile apps or medical devices can be developed.
Given the COVID-19 pandemic presently, hearing screening can be rather
challenging to be carried out. Avoiding close contacts between hospital
staffs and patients are the utmost priority to be adhered upon and
hence, FFCT can be very useful in times of crises as such. With social
distancing we can still carry out hearing screening safely while
minimizing community transmission of this deadly virus among healthcare
workers.22 Hearing screening via mobile-app has an
added advantage of being able to perform faster especially in crowded
hospitals. FFCT is user-friendly for patients whom prefer to maintain
appropriate physical contact and distance from the examiners.