Auditory Deficits in Employees of Business Process Outsourcing (BPO): Need to Take Preventative Action

Abstract

The present study aimed to explore auditory deficits in full-time call center workers. A total of sixty participants participated, which was divided into two groups, viz. experimental group and control group. The complete audiological test battery was performed. On comparing the groups, significant differences were obtained for both ears while analyzing the TEOAEs, PTA1, and PTA2 (high-frequency audiometry). From the results, it can be delineated that BPO employees are at risk for sensorineural hearing loss following continuous noise exposure. We conclude that this type of hearing loss may be considered an iceberg, and to overcome all the issues related to noise exposure, all BPO employees should undergo periodic audiological, psychological, and health screening.

INTRODUCTION

The employees working as call operators may suffer from various adverse health conditions, viz. ophthalmological issues,[1] stress,[1] voice disorders,[1] auditory fatigue,[2] and hearing loss.[3,4,5] The acoustic shock generated by the headsets during the call operation may lead to noise-induced hearing loss (NIHL) and auditory fatigue in the call operators.[3] Moderate noise exposure leads to the shortening of the rootlets of the stereocilia and swelling of the inner hair cells,[6] which may lead to peripheral auditory fatigue.

Call center operators work in an open space with the headsets, so they are exposed to noise via the headsets and environmental noise. For headphone users, a 90–100 dB (A) intensity level for full-time workers at call centers may lead to NIHL. Mazlan[7] reported that using headphones may worsen middle ear problems if there is a history of middle ear infections. From the literature, it can be delineated that call center employees are susceptible to hearing loss. For the same reason, repeated audiological evaluation needs to be conducted regularly to monitor the hearing sensitivity of these individuals. So, the present study aimed to profile the audiological findings of full-time call center workers.

METHOD

Ethical consideration

The study was conducted as per the guidelines of the institute's ethical committee. Before collecting the data, written informed consent was taken from the participants.

Participants

Sixty participants in the age range of 18–40 years were enrolled in the present study. The participants were divided into two groups, as given in Table 1.

Table 1:

Demographic details of the participants

Group	Age (year) Mean±SD	Sex
		Male		Female
		No.	%	No.	%
Experimental (30)	25.40±5.44	27	90.0%	3	10.0%
Control (30)	21.43±2.67	6	20.0%	24	80.0%

Tools and Instrumentation

The complete audiological test battery was performed, which included pure tone audiometry (PTA), impedance audiometry, extended high-frequency audiometry, transient evoked otoacoustic emissions (TEOAEs), and distortion product otoacoustic emission (DPOAE). To conduct the PTA and extended high-frequency audiometry, we used the Madsen Electronics ORBITER922 audiometer. For the impedance audiometry and OAEs, the MAICO immittance audiometer and HIS OAE system were used, respectively. All the tests were conducted in the sound-treated room per the norms of the ANSI/ISO standards for the maximum permissible noise levels.

Procedure

An initial otoscopic examination was conducted to detect any abnormalities of the middle and outer ear that might affect the OAE testing. The test sequence progressed from immittance audiometry, PTA, extended high-frequency audiometry, TEOAEs, and DPOAEs.

Immittance audiometry was performed using a 226 Hz probe tone to assess the middle ear status. The patient was instructed not to speak and swallow during testing. Pressure varied from +100 to -400 daPa, and compliance was between 0.25 cc and 1.75 cc. Pure tone and extended high-frequency audiometry were performed using two-channel Madsen Electronics ORBITER922. The audiometer was calibrated as per ANSI standards (1992). The test was conducted at frequencies 250 Hz, 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz, and 8000 Hz with TDH39 supra-aural headphones, whereas extended high-frequency audiometry was tested at 10000 Hz, 12000 Hz, 14000 Hz, and 16000 Hz using Senheisser HAD200 earphones. The bracketing method was used to conduct the PTA and extended high-frequency audiometry. TEOAEs and DPOAEs were recorded using IHS (USA) OAE system with the standard protocol. TEOAEs were measured using a short duration of 100 µsec, 1024 click stimulus.

Statistical analysis

The statistical analysis of the raw data of each group was performed with SPSS 20.00 version software. The difference between the groups was computed using the Chi-square test for the TEOAE and DPOAE, whereas an independent sample t-test was performed for PTA findings.

RESULTS

Impedance audiometry

All the participants in the present study had bilateral type “A” tympanogram. The range of ear canal volume was 0.23 ml to 0.74 ml, the middle ear pressure was between -16 daPa and 18 daPa, and static compliance was between 0.45 and 1.75 ml in the right ear. The ear canal volume was between 0.48 and 1.65 ml in the left ear, middle ear pressure between -23 daPa and 12 daPa, and static compliance 0.29 and 1.76 ml.

Otoacoustic emission

The analysis revealed that TEOAEs were present in 26.7% and 80% of the right ears of the experimental and control groups, respectively. In contrast, it was absent in 73.3% and 20% of the right ears of the experimental and control groups, respectively. Only 26.7% and 76.7% for the left ear could pass TEOAE screening in the experimental and control groups, respectively, as given in Table 2. Significant differences were obtained for both ears between the experimental and control group.

Table 2:

Comparison of TEOAEs between experimental and control group

Ear	Groups		Chi-square
	Experimental (30)	Control (30)
Right
Present	26.7%	80.0%	0.000
Absent	73.3%	20.0%
Left
Present	26.7%	76.7%	0.000
Absent	73.3%	23.3%

On the analysis of the DPOAEs, 70% and 73.3% of the experimental and control groups, respectively, passed the DPOAEs in the right ear. For the left ear, 76.7% and 80.0% of the study and control group presented DPOAE, as given in Table 3. Statistically, no significant difference was obtained for both ears in comparing the experimental and control groups.

Table 3:

Comparison of DPOAEs between control and study group

Ears	Group		Chi-square
	Experimental (30)	Control (30)
Right
Present	70.0%	73.3%	0.082
Absent	30.0%	26.7%
Left
Present	76.7%	80.0%	0.098
Absent	23.3%	20.0%

Pure tone audiometry

The PTA1 (i.e. the average of hearing thresholds at frequencies 500 Hz, 1000 Hz, and 2000 Hz) and PTA2 (i.e. the average of hearing thresholds at frequencies 10 kHz, 12 kHz, and 14 kHz) were computed. The mean of PTA1 for the right ear was 11.2 ± 3.21 dB and 17.7 ± 1.93 dB for the control and study groups, respectively. Similarly, for the left ear, the mean of PTA1 was 10.0 ± 3 dB and 18.0 ± 2.20 dB in the control and experimental group, respectively. A significant difference (P < 0.01) was obtained in the statistical analysis between the two groups, as given in Table 4.

Table 4:

Comparison of average of PTA1 between the control and study group

Ear	Group (Mean±SD)		P
	Control (30)	Study (30)
Right	11.22±3.21	17.72±1.93	0.000
Left	10.0±3.00	18.00±2.20	0.000

On analysis, the mean of PTA2 for the right ear was 23.9 ± 7.39 dB and 49.1 ± 15.1 dB in the control and study groups, respectively. Similarly, the mean of PTA2 for the left ear was 23.9 ± 9.1 dB and 53.5 ± 18.6 dB for the control and study groups, respectively. A significant difference (P < 0.01) was obtained between the two groups in the analysis, as given in Table 5.

Table 5:

Comparison of average of PTA2 between the control and study group

Ear	Group (Mean±SD)		P
	Control (30)	Study (30)
Right	23.9±7.39	49.1±15.1	0.000
Left	23.9±9.18	53.5±18.6	0.000

DISCUSSION

The present study examined the audiological profile of full-time employees of the call center without any previous history of hearing-related issues. The present study revealed that all the participants had a “type A” tympanogram indicating normal middle ear physiology. Most literature[8,9] also reported the absence of middle ear pathology in BPO employees. In the present study, no significant differences were seen for the DPOAE, whereas significant differences were obtained for TEOAEs. From the previous study[10] and the results of the present study, it can be delineated that TEOAE is more sensitive to outer hair cell damage compared to DPOAE. The otoacoustic emissions give information about the status of sensory hair cells of the inner ear. TEOAEs are more sensitive to changes in the temporary hearing threshold, whereas DPOAEs are most effective in detecting high frequencies.[11]

The person working at the call centers wearing headphones seems to be exposed to a high magnitude of higher frequencies. The previous study[12] reported that individuals who use headphones or earphones showed a decreased amplitude of otoacoustic emissions. A handful of studies are available regarding the audiological evaluation of hearing thresholds. Beyan[4] did a case report in which hearing thresholds were compared pre and post, and it was found that the subject had normal hearing levels initially. However, after 50 months of noise exposure with a duration of 8 hours per day, the subject was diagnosed with NIHL. Results of the present study revealed a significant difference for both PTA1 and PTA2. It was observed that high frequencies were more affected than lower frequencies, and it was attributed to the continuous exposure of noise, which could have reduced the function of the hair cells following irreversible damage to the hair cells.[13]

CONCLUSION AND RECOMMENDATIONS

Based on the present study's results and the past literature, we recommend that sensorineural hearing loss following continuous noise exposure be considered an iceberg. All BPO employees should undergo periodic audiological, psychological, and health screening right from their entry stage to overcome all the issues related to noise exposure. They also need regular follow-ups of all these parameters by employers to monitor their quality of life. The hearing conservation program must be implemented in all industries where noise exposure is common.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.