Comparison of Relative Loudness Judgment in Children using Listening Devices with Typically Developing Children.

Introduction  Loudness perception is considered important for the perception of emotions, relative distance and stress patterns. However, certain digital hearing devices worn by those with hearing impairment may affect their loudness perception. This could happen in devices that have compression circuits to make loud sounds soft and soft sounds loud. These devices could hamper children from gaining knowledge about loudness of acoustical signals. Objective  To compare relative loudness judgment of children using listening devices with age-matched typically developing children. Methods  The relative loudness judgment of sounds created by day-to-day objects were evaluated on 60 children (20 normal-hearing, 20 hearing aid users, & 20 cochlear implant users), utilizing a standard group comparison design. Using a two-alternate forced-choice technique, the children were required to select picturized sound sources that were louder. Results  The majority of the participants obtained good scores and poorer scores were mainly obtained by children using cochlear implants. The cochlear implant users obtained significantly lower scores than the normal-hearing participants. However, the scores were not significantly different between the normal-hearing children and the hearing aid users as well as between the two groups with hearing impairment. Conclusion  Thus, despite loudness being altered by listening devices, children using non-linear hearing aids or cochlear implants are able to develop relative loudness judgment for acoustic stimuli. However, loudness growth for electrical stimuli needs to be studied. Fundação Otorrinolaringologia. This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. ( https://creativecommons.org/licenses/by/4.0/ ).

Introduction

Loudness judgment is utilized for several day-to-day activities. Perception of loudness has been found to help in the judgment of relative distance, 1 2 emotions, 3 4 5 and perception of stress in speech. 6 7 8 In normal hearing children, the ability to perceive loudness similar to adults has been behaviorally observed as early as 4 to 5 years of age. 9 10 Thus, studies have demonstrated that normal hearing children develop the ability to differentiate loudness at an early age.

In individuals using hearing aids with compression, the acoustic signals are modified such that the soft sounds are made audible and the loud sounds are reduced to be within a comfortable level. 11 Musa-Shufani et al 12 found that with high compression ratios in hearing aids intensity differences were difficult to perceive.

Variations in the loudness of a signal has also been reported to be important for the perception of relative distance. 1 2 Strybel et al 2 reported that adults with normal hearing used loudness difference cues for the judgment of relative distance only when the signals were far and not when near. Ashmead et al 1 also observed that adults with normal hearing were able to judge the relative distance when sound pressure cues were preserved, but had difficulty when these pressure cues were removed.

Similar to hearing aids, cochlear implants are also reported to use compression while coding sounds in the auditory system, 13 which could impact the perception of loudness. A wide acoustical input dynamic range of nearly 120 dB is known to be coded within the limited electrical dynamic range of cochlear implants. 14 15 Hence, it is possible that loudness perception may be affected in those using cochlear implants.

Further, intensity coding through cochlear implants has also found to be influenced by various features such as the microphone sensitivity, 16 channel-specific gain, 17 and adaptive dynamic range optimization. 18 19 Loudness perception has also been found to be affected by the pulse width and phase duration used in stimulating a cochlear implant. 14 20 21 22 Increasing the microphone sensitivity is reported to increase the knee point and further result in the representation of low level sound within the electrical dynamic range. 17 23 24 The input acoustic signals above this knee point is reported to result in infinite compression. 17 In spite of increased perception of low level sounds with increase in microphone sensitivity, James et al 16 found that Sprint cochlear implant users had poor preference for high microphone sensitivity setting.

Loudness perception has been evaluated with the use of adaptive dynamic range optimization (ADRO). 18 25 Dawson et al 18 found that, with ADRO, environmental sounds were heard more comfortably. However, James et al 25 reported that 31% of their participants showed no preference to programs with or without ADRO.

Thus, from the review, it can be speculated that various programming/mapping parameters in hearing aids/cochlear implants are likely to affect loudness perception in users of these hearing devices. The literature regarding relative loudness judgement in children using listening device is relatively sparse. It is hypothesized that loudness perception in individuals using digital hearing aids and cochlear implants would be different compared with normal-hearing listeners. Loudness growth perception is recommended to be measured when selecting listening devices. 26 27 28 However, it first needs to be established whether children with congenital hearing loss using listening devices are able to identify the relative loudness of different environmental sounds like their age-matched typically developing children. Hence, the present study aimed to compare relative loudness judgment of children using listening devices with that of age-matched typically developing children.

Methods

Participants

A total of 60 children, in the age range of 6 to 14 years old, were evaluated. Among them, 20 were typically developing children, 20 used binaural digital hearing aids, and 20 wore cochlear implants. Sample characterization is provided in Table 1 . The study was done using a standard group comparison research design. The participants were selected by the experimenters using purposive sampling. The clinical group was selected from those who visited the diagnostic center where the study was conducted. The typically developing children were recruited from schools in and around the diagnostic center. It was ensured that those using listening devices had aided thresholds well within the speech spectrum. All of the participants had normal IQ on the ‘Raven's Progressive Colored Matrices’. 29 The receptive language age of all of the participants was at least 5 years on the ‘Receptive and Expressive Emergent Language Scale’. 30 The demographic details of the hearing aid users and the cochlear implant users are given in Table 2 and Table 3 respectively. Prior to evaluating the participants, informed consent was obtained from the caregivers in accordance with the ethical guidance of the institute. 31

Table 1

Sample characterizations

Parameter	Normal hearing children	Haring aid users	Cochlear implant users
Mean age (SD)	9.25 (2.23)	9.25 (1.51)	9.85 (2.95)
Number of males	9	13	12
Number of females	11	7	8
Total number of children	20	20	20

Abbreviation: SD, standard deviation.

Table 2

Demographic details of the participants using hearing aids

Participant	Age (Years old)	Gender	No. of Years hearing aids were used	Aided thresholds (in dB)
				Ear	500 Hz	1 kHz	2 kHz	4 kHz
1	11	Female	8	R	40	55	65	70
				L	25	25	50	50
2	6	Male	4	R	25	30	35	40
				L	20	30	30	35
3	9	Female	5	R	35	40	40	40
				L	40	25	35	40
4	9	Male	4	R	25	30	25	30
				L	25	30	30	35
5	9	Male	7	R	25	25	30	35
				L	20	25	25	30
6	8	Female	7	R	30	35	40	40
				L	35	35	30	35
7	11	Male	6	R	30	40	45	45
				L	30	40	30	30
8	9	Male	7	R	30	30	35	40
				L	30	30	40	50
9	11	Female	7	R	35	45	40	50
				L	40	45	40	45
10	9	Female	5	R	25	25	35	50
				L	30	30	35	45
11	8	Male	6	R	35	40	45	60
				L	40	40	35	60
12	11	Male	7	R	30	25	30	25
				L	35	35	40	35
13	12	Male	2	R	25	25	35	30
				L	30	30	35	30
14	11	Male	8	R	30	25	25	30
				L	25	25	25	20
15	9	Female	7	R	40	45	35	50
				L	40	40	45	45
16	8	Male	2	R	40	40	40	50
				L	40	40	45	55
17	10	Male	8	R	30	35	40	35
				L	35	35	40	35
18	8	Male	6	R	30	25	45	50
				L	45	30	40	55
19	7	Female	3	R	35	40	35	50
				L	30	45	45	50
20	9	Male	8	R	40	30	30	45
				L	25	30	30	40

Abbreviations: L, Left ear; R, Right ear.

Table 3

Demographic details of children using cochlear implants

Participant	Age (Years old)	Gender	No. of Years of implant use	Aided thresholds						Devices details
				Ear	500	1k	2k	4k	Implant	Processor	Coding Strategy	Other Settings
1	15	Male	13	R	20	15	25	25	Med El Sonata 100	Opus 2 Power	FSP4	–
2	12	Male	7	R	25	25	25	30	Med El Sonata 100	Tempo+	CIS+	–
3	6	Female	1	L	25	20	25	25	Hi Focus Hires 90K	Neptune	HiRes Optima S	Clear Voice Medium
4	6	Male	4	R	40	30	45	40	Hi Focus Hires 90K	Neptune	HiRes Optima S	–
5	11	Male	1	R	35	35	35	35	Hi Focus Hires 90K	Harmony	HiRes Optima S	Clear Voice Medium
6	6	Male	2	R	30	35	30	30	Digisonic SP	Saphyr SP	Crystalis XDP	Voice Track Low
7	8	Female	3	R	25	30	30	30	Digisonic SP	Saphyr SP	Crystalis XDP	Voice Track low
8	14	Male	7	L	25	30	30	25	Freedom CI 24RE	Freedom	ACE	ADRO, ASC
9	8	Female	4	R	25	25	25	30	Freedom CI 24RE	CP802	ACE	ADRO, ASC
10	11	Male	6	R	20	25	25	25	Freedom CI 24RE	CP810	ACE	ADRO, ASC
11	5	Male	3	R	10	10	10	10	Freedom CI 24RE	CP810	ACE	ADRO, ASC
12	13	Female	2	R	20	20	20	25	Freedom CI 24RE	CP802	ACE	ADRO, ASC
13	8	Male	6	L	15	15	15	15	Freedom CI 24RE	Freedom	ACE	ADRO
14	13	Female	7	L	25	20	25	20	Nucleus 24(R)	Sprint	ACE	ADRO, ASC
15	12	Female	10	L	20	25	25	20	Nucleus 24(R)	CP810	ACE	ADRO, ASC
16	12	Male	8	R	20	20	25	20	Nucleus 24(R)	Sprint	ACE	ADRO
17	7	Female	4	L	20	20	15	10	Nucleus 24(R)	CP802	ACE	ADRO, ASC
18	10	Male	5	R	25	25	25	30	Freedom CI 24RE	CP802	ACE	ADRO, ASC
19	8	Male	4	R	30	25	25	25	CI 422	CP910	ACE	Scan
20	12	Female	7	R	25	25	25	25	CI 512	CP810	ACE	ADRO, ASC

Abbreviations: ACE, Advanced Combination Encoder; ADRO, Adaptive Dynamic Range Optimization; ASC, Auto Sensitivity Control; CIS, Continuous Interleaved Sampling; FSP, Fine Structure Processing; L, Left ear; R, Right ear.

The normal-hearing children had bilateral air and bone conduction thresholds ≤ 15 dB in the octave frequencies 250 Hz to 8 kHz and 250 Hz to 4 kHz, respectively. None of them had any other significant history of speech and hearing, otological or medical problems.

Among the children using hearing aids, four had profound hearing loss and one had moderate hearing loss. The remaining had moderately-severe to severe hearing loss (mean PTA = 74.79 dB HL; standard deviation [SD] = 13.15; range = 43.33 to 103.33 dB HL). All but 2 had symmetrical hearing loss, with the mean aided thresholds for 500 Hz, 1,000 Hz, 2,000 Hz and 4,000 Hz being 36.16 dB HL, SD being 6.78 and the range being 23.75 to 57.50 dB HL ( Table 2 ). They used binaural digital behind-the-ear hearing aids. The compression ratio used by all of the participants varied from 1.6:1 to 3.2:1, based on the recommendation of audiologists. The age at which the children started utilizing their hearing aids ranged from 1 to 10 years old, with the mean age being 3.45 years old. Although a few of the children started using their hearing aids late, they were able to develop a fairly high level of language due to the degree of hearing loss being lower. The number of years of use of the hearing aids ranged from 2 to 8 years. Only participants who consistently used binaural hearing aids were included in the study.

The children using cochlear implants wore their device in one ear for a minimum of 1 year and had stable maps. Among them, 13 children also wore a behind-the-ear hearing aid in the non-implanted ear. The mean aided threshold for 500 Hz, 1,000 Hz, 2,000 Hz and 4,000 Hz of the participants using cochlear implants was 24.44 dB HL, with SD being 6.52 and the range being 10 to 38 dB HL ( Table 3 ). Among those who wore hearing aids in the nonimplanted ear, the mean aided threshold for 500 Hz, 1,000 Hz, 2,000 Hz and 4,000 Hz was 58.83 dB HL with SD being 20.08 and the range being 37.5 to 101.25 dB HL. The cochlear implants worn by the participants varied. Among them 2 used Med-EL devices (Innsbruck, Tyrol, Austria), 3 used Advanced Bionics devices (Los Angeles, California, USA), 2 used Neurelec devices (Vallauris, France) and 13 used Cochlear Nucleus devices (Sydney, NSW, Australia). The age at which children started using cochlear implant ranged from 2 to 11 years old (mean = 4.65 years). The number of years of use of the cochlear implant ranged from 1 to 13 years, with only 2 participants using their device for 1 year.

Material

To evaluate relative loudness judgment, a test was developed. The ‘Relative Loudness Judgment Test’ consisted of 30 sets of stimuli, each consisting of two pictures depicting sounds produced by common objects/situations ( Fig. 1 ). Initially, 38 of these pairs were developed and 10 normal-hearing adults were required to judge whether the stimuli in each pair produced distinctly different loudness. Based on their responses, three pairs that were considered ambiguous were excluded from the test. The remaining 35 stimulus pairs were pictorially depicted, with each picture having a dimension of 12 × 10 cm. A total of 25 adults, who had not judged the material earlier, were instructed to describe what the pictures indicated as well as to judge whether the objects/situations in each pictorial pair depicted distinctly different loudness. These adults included parents of typically developing children, parents of children with hearing impairment, and speech and hearing professionals. As three of the pictures were labeled as being ambiguous, they were eliminated and the final ‘Relative Loudness Judgment Test’ contained 32 pairs of stimuli, of which 2 pairs served as practice stimuli.

Fig. 1

Sample of a stimulus-pair used in the ‘Relative loudness judgment test’, with the figure in the left depicting the louder stimulus.

Further, the selected 30 pairs of test stimuli were categorized as being ‘grossly different’ and ‘finely different’. This categorization was based on the responses of 10 adult participants. ‘Grossly different’ stimuli were those pairs of stimuli that were considered to have distinctly different loudness by at least 80% of the adults. The ‘finely different’ stimuli included pairs that were considered as having fine difference in loudness by at least 80% of the participants and pairs having no consensus as being gross or finely different. From the responses of the participants, 17 stimulus pairs were labeled as ‘Grossly different’ and 13 were considered to be ‘Finely different’. Description of the test stimuli are provided in Appendix A .

Instrument and Environment

To determine the hearing status of the participants, a Piano diagnostic audiometer (Inventis, Padova, Italy) was used. The absence of any middle ear pathology was confirmed with the help of a GSI Tympstar immittance audiometer (Grason-Stadler, Eden Prairie, MN, USA). A HP Envy Laptop (Intel Core i7) (Hewlett-Packard, Palo Alto, CA, USA), loaded with the software ‘Paradigm’ (v2.5.0.68) designed by Tagliaferri 32 was used to test relative loudness judgment.

The audiological tests were performed in a sound-treated suite that met the specification of ANSI/ASA S3.1–1999 33 The loudness testing was performed in a distraction-free quiet room.

Procedure

Those participants who met the participant selection criteria were subjected to further evaluation. The children were reported to use their prescribed hearing aids/cochlear implants regularly in the settings recommended by qualified audiologists.

All of the participants were tested with 32 pairs of stimuli (2 practice and 30 test stimuli). The pairs of stimuli were presented through the Paradigm software, loaded in the laptop, kept at a distance of 0.5 m and at 0° azimuth from the head of the participants. Pairs of pictures were presented one after the other and the participants were instructed to point or click on the picture that depicted the louder sound. If a child could not use the computer mouse, the examiner clicked on the selected picture. Those who had difficulty with the practice items were reinstructed and it was once again demonstrated what they were expected to do. The time taken to evaluate each child was ∼ 10 minutes and the testing was done in a single session. The Paradigm software was programmed to automatically assign a score of 1 for each correct response and of 0 for each incorrect response. Thus, the maximum possible score that could be obtained was 30. Test-retest reliability was done on 10% of the participants, with representation from all three groups.

Analyses

Descriptive and inferential statistics were conducted using IBM SPSS Statistics for Windows. Version 21 (IBM Corp., Armonk, NY, USA). The Shapiro-Wilk test performed to check the normality indicated that the data were not normally distributed ( p  < 0.05), hence nonparametric statistics was done. Both descriptive and inferential statistics were done.

Results

The results are provided to depict the comparison of the relative loudness judgment between the participant groups (normal-hearing children, children using hearing aids, and children using cochlear implants). Additionally, comparison of scores for the ‘grossly different’ and ‘finely different’ stimulus-pairs within each group as well as between the three participant groups are given. The relationship between the duration of experience with the listening device and relative loudness judgment scores are also presented.

Comparison of Relative Loudness between the Participant Groups

The means and SDs as well as medians and ranges of the overall scores for the 30 test items are depicted for the 3 participant groups in Table 4 . It can be noted from the table that the relative loudness judgment scores for all the participants approximated the maximum possible score. However, the median scores obtained for the normal hearing children was higher than that of the hearing aid users and the cochlear implant users. The range was also found to be higher in the clinical population when compared with the normal-hearing group.

Table 4

Comparison of normal hearing children, children using hearing aids and children using cochlear implants

Participant Groups	n	Mean#	SD	Median	Range	p-value*
Normal hearing	20	29.60	0.60	30.00	28 to 30	0.06
Hearing aid users	20	29.10	1.12	29.00	25 to 30
Normal hearing	20	29.60	0.60	30.00	28 to 30	0.008*
Cochlear implant users	20	28.35	2.00	29.00	22 to 30
Hearing aid users	20	29.10	1.12	29.00	25 to 30	0.29
Cochlear implant users	20	28.35	2.00	29.00	22 to 30

Abbreviations: n , number of participants; SD, standard deviation.

Note: # Maximum possible score = 30; *Mann-Whitney U test results with Bonferroni correction for 3 comparisons.

The Kruskal-Wallis test of significance was conducted to compare the ability of the three participant groups to judge relative loudness. The results revealed that there was a significant difference in the ability to judge relative loudness between the three groups [ H (2) = 7.29, p  = 0.02]. Furthermore, to determine which of the pairs of groups differed from each other, Mann-Whitney U tests were performed. The ability to judge relative loudness did not significantly differ between the normal-hearing listeners and the hearing aid users [ U  = 139.00, p  = 0.06, r  = - 0.29] as well as between children using hearing aids and children using cochlear implants [ U  = 164.00, p  = 0.29, r  = - 0.17]. However, a significant difference was observed between the typically developing children and the children using cochlear implants [ U  = 113.00, p  = 0.01, r  = - 0.42] ( Table 4 ).

Comparison of Grossly Different and Finely Different Stimulus-pairs within each Group

Within each participant group, the relative loudness judgment scores for stimuli that were categorized as ‘Grossly different’ were compared with stimuli that were categorized as ‘Finely different’. As there were unequal numbers of stimulus-pairs between the two categories (gross and fine), the scores were converted into percentages. Table 5 represents the mean, SD, median and range of the percentage scores.

Table 5

Comparison of percentage scores of ‘Grossly different’ and ‘Finely different’ stimulus-pairs within each group

Participant Groups	Loudness difference of stimulus-pairs	Mean %	SD	Median %	Range	p-value
Normal Hearing	Grossly different	98.82	2.41	100	5.88	0.49
	Finely different	98.46	4.02	100	15.38
Hearingaid users	Grossly different	96.76	4.86	100	17.65	0.46
	Finely different	96.53	4.65	100	15.38
Cochlear implant users	Grossly different	93.82	6.74	94.11	23.53	0.62
	Finely different	95.00	7.60	100	30.77

Abbreviation: SD, standard deviation.

Notes: *Wilcoxon signed rank tests, significance level = 0.05; r  = effect size.

It was noted that in the normal-hearing children the mean percentage scores for the ‘Finely different’ category was marginally poorer than for the ‘Grossly different’ category. However, the ‘Finely different’ category tended to have more variability than the ‘Grossly different’ category. Likewise, the mean scores in the two groups with hearing impairment differed marginally across the two levels of difficulty. On the other hand, the variability between the two levels of difficulty did not differ much in both groups of children with hearing impairment.

Furthermore, to establish whether the scores were statistically different, a Wilcoxon signed rank test was done within each group to compare the percentage scores between categories. It was noted that there was no significant difference between the two categories within each group ( Table 5 ).

Comparison of Grossly and Finely Different Stimuli-pairs between Participant Groups

The Kruskal-Wallis test of significance was conducted to compare the relative loudness judgment scores across the three participant groups for the stimuli categorized as ‘Grossly different’ and ‘Finely different’. The results indicated that there was a significant difference among the three groups for the ‘Grossly different’ stimuli [ H(2)  = 8.392, p  = 0.015], but not for the ‘Finely different’ stimuli [ H(2 ) = 4.260, p  = 0.119]. Since there was a significant difference between the groups for the ‘Grossly different’ stimuli, further analysis was done and no further analysis was done for the ‘Finely different’ stimuli.

Pair-wise comparisons of the groups using Mann-Whitney U tests revealed that for the ‘Grossly different’ stimuli there was no significant difference between the typically developing children and children using hearing aids [ U  = 156.00, p  = 0.242, r =  - 0.234]. Also, there was no significant difference in the judgment of relative loudness between children using hearing aids and children using cochlear implants [ U  = 148.500, p  = 0.165, r  = - 0.24]. However, there was a statistically significant difference between the typically developing children and children using cochlear implants [ U  = 108.00, p  = 0.012, r  = 0.449].

Relation between the Duration of Usage of Listening Device and Relative Loudness Judgment

To study if a correlation exists between duration of useful listening experience with the hearing devices and the ability to judge relative loudness, the Spearman correlation was done. For the typically developing children, the hearing experience was calculated as their chronological age. With all three groups combined, no significant correlation was observed between the duration of listening experience and the overall scores obtained on the relative loudness judgment test [ r (58) = 0.22, p  > 0.05]. Similarly, the correlation remained poor for the typically developing children [ r (18) = 0.12, p  > 0.05], children using hearing aids [ r (18) = -0.28, p  > 0.05], and children using cochlear implants [ r (18) = 0.14, p  > 0.05].

The correlation of years of experience with the listening devices was also studied for the ‘Grossly different’ and the ‘Finely different’ stimuli for each group of participants separately. For the ‘Grossly different’ stimuli, the correlation was poor for the typically developing children [ r (18) = 0.294, p  > 0.05], children using hearing aids [ r (18) = 0.212, p  > 0.05] and children using cochlear implants [ r (18) = 0.253, p  > 0.05]. Likewise, for the ‘Finely different’ stimuli, the correlation was poor for the typically developing children [ r (18) = -0.119, p  > 0.05], children using hearing aids [ r (18) = -0.559, p  > 0.05] and children using cochlear implants [ r (18) = 0.077, p  > 0.05].

The responses of the 10% ( n  = 6) of the participants on whom the ‘Relative loudness judgment test’ was repeated were analyzed using Cronbach α. As the α value was 0.81, it indicated that the test-retest reliability was high. Also, the percentage of agreement between their responses was calculated. It was found to range between 90% to 100%, indicating a good test-retest agreement.

Thus, the findings of the study indicated that a statistically significant difference in relative loudness judgment scores was observed between the typically developing children and the children using cochlear implants. However, no such difference was obtained between the typically developing children and those using hearing aids, as well as between the two groups with hearing impairment. All of the three participant groups demonstrated no significant difference in perceiving the ‘Grossly different’ and ‘Finely different’ pairs of stimuli. However, there was a statistically significant difference when the scores of ‘grossly different’ stimuli were compared between the typically developing children and the children using cochlear implants. Furthermore, it was noted that there was no correlation between the experience with the listening device and the loudness judgment scores obtained.

Discussion

The results of the study are discussed with reference to the comparison of the relative loudness judgment between the participant groups (20 normal-hearing children, 20 children using hearing aids, and 20 children using cochlear implants); comparison of scores for the ‘Grossly different’ and ‘Finely different’ stimuli pairs within each group, as well as between the three participant groups; and the relationship between the duration of experience with the listening device and relative loudness judgment scores.

Comparison of Relative Loudness Judgment between the Participant Groups

All of the three groups of children obtained fairly high scores on the ‘Relative loudness judgment test’, there being no statistically significant difference between the typically developing children and those using hearing aids. This indicates that despite the hearing aids being non-linear and compressing the acoustical signals, children using these devices aids were able to perceive relative loudness like their normal-hearing peers.

This finding in the present study is supported by Shi et al, 34 who found that adults using hearing aids were able to perceive the loudness of environmental sounds. Also, it was noted by Schmidt et al 35 that children using hearing aids could use the intensity cues to perceive emotions similar as normal-hearing listeners.

Thus, it can be construed that non-linear hearing aids do not hamper the perception of loudness of sounds. Children using these devices are able to develop knowledge of the relative loudness of different signals in the environment. Hence, administering tests of loudness growth, as a part of hearing aid selection/fitment, can be performed on those who are at least 6 years old.

However, in the current study, children using cochlear implants were found to have significantly poorer judgment of relative loudness compared with the normal-hearing children. A possible reason for the children using cochlear implants having poorer relative loudness judgment could be due to them having a higher differential limen for intensity. Adults using cochlear implants have been reported earlier to have a higher differential limen for intensity as compared with normal-hearing individuals by Nikakhlagh et al. 36 It is possible that, like adults, children using cochlear implants also have a higher difference limen for intensity.

Further, cochlear implants are known to have algorithms that make soft sounds loud and loud sounds soft. 37 The majority of the children evaluated in the current study used cochlear implants that utilized these algorithms. This could have affected their loudness judgment abilities. However, all but one child using cochlear implants obtained scores that were > 80%. This indicates that despite performing poorer than typically developing children, these children also had fairly good relative loudness judgment abilities.

Comparison of ‘Grossly Different’ and ‘Finely Different’ Stimuli-pairs within and between Participant Groups

Within all three participant groups, no significant difference was observed between the scores for ‘Grossly different’ and ‘Finely different’ stimuli. This indicates that children are able to perceive relative loudness in a similar manner even if the loudness of pairs of stimuli is not very different or is difficult to judge. However, across the participant groups, a significant difference was seen between the typically developing children and the children using cochlear implants only for the ‘Grossly different’ stimuli and not for the ‘Finely different’ stimuli. This could have happened as the variability in scores for the ‘Grossly different’ stimuli were the least in the typically developing children, but was relatively much higher in the children using cochlear implants. This difference in variability between the two groups could have resulted in the significant difference for this category of stimuli. Thus, although adults categorized some of the stimuli as being grossly different and others as being finely different, all of the children perceived them with equal ease. However, the children using cochlear implants demonstrated varied loudness judgment responses. On examination of the raw data of the children using cochlear implants, it was observed that that the children with poorer scores varied in terms of the company/model that they used. Hence, the poorer performance in a section of the children using cochlear implants cannot be attributed to the features in the device worn by them.

Relation between the Duration of Experience with the Listening Device and Relative Loudness Judgment

The duration of hearing device usage was found to have no significant effect on the relative loudness judgment ability of children. This was seen in all three groups. It can be inferred from the findings of the study that children using hearing aids for just 2 years or children using cochlear implants for just 1 year are able to make judgments about loudness of stimuli in the environment.

Conclusions

The findings of the study revealed that children with hearing impairment using cochlear implants are not able to develop the ability to judge relative loudness to the same extent as typically developing children. However, children using nonlinear hearing aids were able to respond similarly to typically developing children. Despite the children with cochlear implants performing poorer than the typically developing children, they obtained fairly high scores indicating that they did have the ability to judge relative loudness.