Abstract

Methods

This project was part of a large online survey known as Sound Check Australia, which was approved by the Australian Hearing Human Research Ethics Committee.

Materials

The full survey took ~20 to 30 minutes to complete (although this varied between participants because the number of questions differed depending on individual responses) and included several modules. These covered a range of questions regarding participants' health, how often they listened to audio with headphones, participation in leisure activities and noisy work environments, and attitudes to noise and hearing loss. After demographic information was recorded, participants were asked how often “they used headphones or earbuds to listen to audio files on a PLD.” The response options were: regularly (>4 hours total during the past month), occasionally (<4 hours total during the past month), or not within the past month. All those who had used PLDs for more than 4 hours in the last month were later presented with further questions on PLD usage. Participants were asked to estimate the hours spent each month using a range of different PLD devices across different listening environments. For each usage estimated to be greater than 5 hours per month, additional questions were asked regarding estimated volume levels and transducer type. Participants were asked to estimate their usual listening volume as a percentage of the total maximum volume level for the device and to indicate from a selection of described transducer types (with example images) the headset/earphones generally used.

Participants also were asked (in a separate module) a series of questions about their hearing health including self-reports of hearing loss (question 1), changes in hearing (question 2), experience of tinnitus (question 3), hearing health (questions 4, 5), and speech perception ability in different contexts (questions 6, 7, 8; see Table 1 ).

Table 1

Hearing Health by Population and Risk Group Status*

Questions and Response Options	All PLD Users	Young Adult PLD Users (18–35 y)
		Low Risk	High Risk	Very High Risk
n	3,929	1,569 (82%)	203 (10%)	137 (7%)
Age, mean (SD)	30 (14)	25.2 (4.6)	25.1 (4.6)	25.2 (4.6)
% male	53	54	60	49
1.Do you feel you have a hearing loss † ?
No	59	61	46	49
Yes	41	39	54	51
2.Over time, have you noticed any change in your hearing ability?
No change	46	50	38	45
Yes, improved a little	3	3	4	2
Yes, Improved a lot	1	.4	1	0
Yes, worsened a little	48	46	55	47
Yes, worsened a lot	2	1	2	6
3.Have you ever experienced tinnitus? †
Never/almost never	29	28	22	25
Occasionally	29	32	33	28
Sometimes	23	26	25	30
Frequently	11	10	13	12
Always/almost always	8	5	8	5
4.In general, how would you describe your hearing ability?
1.Very poor/can hardly hear	0	0	1	0
2.	1	1	1	2
3.	10	9	11	11
4.Neither good nor poor	18	18	17	20
5.	22	21	21	22
6.	35	38	35	33
7.Perfect/near perfect	15	14	16	12
5.Are you ever bothered by feelings that your hearing is poor?
Never/almost never	44	43	42	39
Occasionally	29	30	27	23
Sometimes	22	21	24	30
Frequently	6	5	6	8
Always/almost always	1	0.4	2	0
6.When several people are talking in a room, do you have difficulty hearing an individual conversation?
1.Never/almost never	24	25	22	24
2.Occasionally	31	34	29	25
3.Sometimes	25	25	21	23
4.Frequently	15	13	19	18
5.Always/almost always	6	4	9	10
7.Can you follow the conversation when you are at a large dinner table?
1.Always/almost always	42	43	34	36
2.Frequently	35	38	40	37
3.Sometimes	16	15	18	18
4.Occasionally	5	4	6	7
5.Never/almost never	2	1	2	3
8.Overall, I would judge my ability to make out speech or conversations to be:
1.Good	48	50	41	46
2.Average	33	34	37	30
3.Slightly below average	16	14	17	18
4.Poor	3	2	4	7
5.Very poor	0	0	0	0

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PLD, personal listening device; SD, standard deviation.

*Note: participants reporting a permanent hearing loss are not included in data set.

^†Where survey allowed for responses of “Unsure,” these were removed prior to analysis.

Results

Age, Gender, and Educational Characteristics

As shown in Table 2 , the study cohort consisted of PLD listeners age between 15 and 91 years (mean [M]=31.4, standard deviation [SD]=15.3). The majority (59%) of listeners were age 29 or younger; however, regular PLD use was prevalent among older individuals with 17% of users age 50 or over. There was a slightly higher proportion of males than females, and the majority of participants were highly educated, with 46% holding a university degree.

Table 2

Distribution of Age, Gender, and Highest Level of Education Attained in the PLD User Population

Variable	n	% of Sample	Mean Listening Duration (h/mo)	Mean Listening Volume (%)
Age
15–19	1,040	25	88	53
20–29	1,437	34	72	55
30–39	640	15	61	55
40–49	375	9	46	53
50+	693	17	47	48
Sex
Male	2,233	53	68	53
Female	1,932	47	67	53
Education
No formal schooling	3	<1	*	*
Primary	21	<1	73	58
Some secondary	848	20	89	54
Completed secondary	777	19	72	55
Trade/technical qualification	631	15	63	53
University degree/postgrad	1,904	45	58	52

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PLD, personal listening device.

*Means not reported due to small group size.

Listening Volumes, Durations, Environments, Devices, and Transducers

Listening Volumes

The mean self-reported PLD listening volume was 53.3% of maximum volume setting (SD=21.1). As shown in Table 2 , males and females reported listening volumes at similar levels, and listening volumes were similar across most age groups. However, those age 50 and above showed significantly lower listening volumes than all other age groups ( F [4, 3,525]=12.95, p <0.001).

Listening Durations

Listening duration data were analyzed to obtain an overview of how participants used PLDs. The total hours of listening per month were calculated, overall, and across different groups and activities to examine PLD usage profiles (see Table 2 ).

PLD mean listening durations differed significantly by age ( F [4, 4,048]=35.83, p <0.001). Mean monthly listening hours for 15- to 19-year-olds (M=88, SD=93) were significantly higher than that for 20- to 29-year-olds (M=72, SD=77) and 30- to 39-year-olds (M=61, SD=74), which were higher again than the mean monthly listening hours for those age 40 to 49 years (M=46, SD=53) and 50 to 59 years (M=47, SD=56). No significant differences were found in mean listening hours between 20- to 29- and 30- to 39-year-olds, or those age 40 to 49 and 50 or over. There was also no significant difference in mean listening durations for males and females ( t [4,001]=0.36, p =0.722).

Listening Environments

Across the sample, the highest proportion of listening time occurred during home-based leisure (23%), followed by working in quiet (18%) and commuting (16%; see Fig. 1 ). The percentage of individuals listening in each environment is shown in Fig. 2 ; PLD use during leisure time at home and commuting were most popular with 63% of individuals reporting participation. The next two most popular activities were working or studying in a quiet environment and exercising outdoors, which also showed participation rates of more than 50%.

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Figure 1

Percentage of total listening duration by listening environment.

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Figure 2

Percentage of participants who reported using PLDs at least once in each listening environment.

Participants' mean reported listening volumes for each listening environment are shown in Fig. 3 . Reported listening volumes were generally higher for environments with greater background noise (such as exercising, commuting, working in busy environment) than quieter environments.

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Figure 3

Mean volume (as percent of maximum PLD volume), by listening environment. PLD, personal listening device.

Devices and Transducer Types

MP3 devices, computers, and phones were the most commonly used devices, making up a combined 88% of total listening duration across the sample ( Fig. 4 ). Transducer use was recorded in relation to individual listening activities, with many participants using different transducers for different listening environments and/or devices. As shown in Fig. 5 , more than a quarter of participants' overall listening time was undertaken using the default earbuds or headsets that came with their nominated device. For the remaining listening hours, earbuds, which were generally reported to be used more for phones/MP3 devices for commuting and exercising, were more popular than headphones, which were predominantly used with computers or while spending leisure time at home. Only a small percentage of listening time was undertaken with noise-canceling devices (7.5%).

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Figure 4

Percentage of total listening duration by device type.

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Figure 5

Percentage of total listening duration by transducer type. ( Default refers to the transducer that came with the device, and may include either earbuds or headphones.)

Risk Categorization

Participant risk status was calculated based on participants' self-reported PLD listening volumes and durations with respect to reported transducer type used.

To determine the relevant decibel level corresponding to participants' reported listening levels, we used three regression equations provided by the authors of an earlier publication that examined PLD listening habits. ¹⁵ Table 3 shows the equations provided by Portnuff (written communication, April 2017) across three common transducer types.

Table 3

Regression Equations for Converting Reported Percentage Volumes to Decibel Equivalents, by Transducer Type*

Transducer Type	Regression Equation	Corresponding Transducer Types (Current Study)
Earbuds	0.6143 x +39.395	Default earbuds/earbuds
Isolator	0.6159 x +42.561	Canal/noise-canceling earbuds
Supra-aural	0.6147 x +34.939	Supra-aural/circumaural/noise-canceling headphone

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*Where x represents reported device volume as a percentage of maximum (based on data presented in Portnuff et al ¹⁵ ).

For each listening event, participants' reported listening level was converted to a decibel estimate by selecting the regression equation most appropriate for the transducer type used. Listening durations were then converted from the reported hours per month to daily duration based on a 30-day month. This duration information, along with the decibel values previously described were used to calculate exposure estimates for each activity, as a percentage of the daily recommended workplace exposure limit (where 100%=8-hour 85 dB L _Aeq ). Activity exposure estimates were summed to give a PLD daily noise dose (DND) for each participant.

Of the 4,185 PLD users, 3,578 participants provided suitable volume and duration details to calculate their risk status (see Table 4 ). Participants receiving less than 0.5 PLD DND from all their listening activities were classified as low risk. Participants whose PLD DND was greater than 0.5 were categorized as high risk, and those with a PLD DND over 3 as very high risk. A total of 401 participants (over 10% of all PLD users) had exposures of greater than 1 PLD DND—that is, they were receiving exposure levels from PLDs alone that exceeded the maximum recommended daily workplace exposure guidelines.

Table 4

Risk Classification and Related PLD DNDs*

Risk Status	PLD DND Criteria	n (%)	Mean PLD DND (SD)
Low risk	<0.5	3,017 (84.8)	0.05 (0.10)
High risk	0.5–3	338 (9.4)	1.24 (0.65)
Very high risk	>3	223 (6.2)	11.26 (11.6)

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DND, daily noise dose; PLD, personal listening device; SD, standard deviation.

*1 PLD DND=DND.

A significant difference was found across the three risk groups with respect to age ( F [2, 3,577]=30.35, p <0.001). Post hoc tests showed that the age of low-risk participants (M=32, SD=15) was significantly higher than that of high-risk and very-high-risk participants (M=28, SD=12 and M=25, SD=10, respectively); however, the mean age of the latter two risk groups did not differ from each other ( p =0.210).

Pearson chi-square showed a significant difference in the proportion of males and females in the three risk groups (χ ² [2, N =3,562]=7.13, p =0.028), with a slightly higher percentage of females (54%) than males in the very-high-risk group.

There were significant variations in total hours per month of PLD listening across the three risk groups ( F [2, 3,551]=155.59, p <0.001). Tukey post hoc tests showed significant increases from low- (M=65, SD=68) to high-risk groups (M=103, SD=92), and from high- to very-high-risk groups (M=148, SD=124; p <0.001).

The durations of PLD usage for individual activities also varied significantly across the three risk groups, with the exception of going to sleep. Activity durations were generally greatest for the very-high-risk group, followed by the high- and then low-risk groups (see Fig. 6 ). However, there was no difference between the high- and very-high-risk groups for leisure time at home or working in a busy environment or between the low- and high-risk group for working in quiet or busy environments, or working around the house. Furthermore, only the low- and very-high-risk groups differed significantly in the hours spent using PLDs while watching sport.

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Figure 6

Mean monthly activity duration participation, by risk group. ns, not significant.

There was a significant difference in mean listening volumes across the three risk groups ( F [2, 3,518]=662.81, p <0.001). Post hoc tests showed that very-high-risk participants listened at significantly higher volumes (M=84, SD=14) than high-risk participants (M=75, SD=13), who in turn listened at significantly higher volumes than low-risk participants (M=49, SD=19).

Significant effects for risk groups also were seen for mean listening volumes in the various listening activities (see Fig. 7 ). Participants in the high-risk status group reported listening at significantly higher levels than participants in the low-risk status group for all activities. The very-high-risk group showed significantly higher mean listening levels than the high-risk group for each activity except watching sports (where participation numbers were low). Furthermore, the very-high-risk group was most likely to report mean listening levels above the critical 80% volume level.

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Figure 7

Mean activity listening volume (by risk group). ns, not significant.

Discussion

This study aimed to profile PLD users in Australia, identify their listening habits, calculate the proportion potentially at risk for NIHL from their listening behaviors, and examine whether risk is associated with self-reported hearing difficulties.

The profile of PLD participation rates showed a disproportionately high level of use by younger listeners compared with older age groups. Listening durations and volumes also showed an association with age, with listening durations decreasing with age and those age 50 and over listening at significantly lower volume levels than younger users. Age was also a significant factor overall in relation to risk status, with higher-risk groups having a younger average age overall. On the other hand, there was no significant difference in gender between the risk groups. These findings are consistent with several other studies that have found PLD usage is associated with age but not gender. ^{3 4 25}

Listening volumes were highest for activities associated with higher levels of background noise, such as exercising and commuting. Activities associated with less ambient noise, such as working in a quiet environment and going to sleep, showed the lowest listening volumes. These results support previous findings that background noise affects listening levels. ^{18 19 20} It should be noted, however, that those activities associated with the highest listening levels (e.g., exercise-related activities) were among those with the lowest levels of participation (hours per month). Providing hearing health education to PLD users, therefore, needs to reference not only activities with high listening volumes but also those with a high listening durations . PLD hearing health messages should avoid focusing only on volume reduction as a single solution. Rather, hearing health messages may be more effective if a flexible approach is taken that promotes decreasing listening volumes and/or decreasing durations, whichever is most relevant on an activity-by-activity basis. For example, users may be encouraged to find ways to decrease their PLD volumes while exercising, while for at-home activities, the focus may be to encourage listeners to decrease the amount of time spent using PLDs. For activities with high listening volumes and duration, participants should be encouraged to be more aware of their usage and decrease either or both volume and duration.

In general, earbud and canal earbuds (where earbuds are inserted into the ear) were the most commonly reported transducer type used, particularly preferred for phones and MP3 devices. This is most probably due to their ease of portability, convenience, and availability, because this style is also generally the transducer provided with PLDs. Thus, it is likely that many of the participants reporting using these were in fact using the default transducers. Furthermore, although the current survey did not differentiate between styles within the default option provided, it is likely that a large proportion of those participants reporting using these transducers were using earbuds. Headphones were most often used with the computer or while spending leisure time at home where less portability is required.

Perhaps the most important finding to emerge from this study was that ~15% of the PLD users surveyed appear to be at risk of hearing damage from high listening volumes coupled with excessive listening duration. Although this finding is on the lower end of previous estimates of prevalence, which range from 16.7 to 51.9%, ^{4 17 18} it is nonetheless a substantial proportion of listeners when considering the overall popularity of PLD use. The significant differences in listening duration and volume across the three risk status groups indicate that both volume and duration are significant contributors to exposure levels.

Of particular concern are the 400 participants (over 10% of PLD users) whose exposure exceeded 1 PLD DND. These individuals are exceeding, from PLD usage alone, the total DND recommended by workplace noise exposure guidelines. As such, these listening behaviors place individuals at considerable risk of NIHL particularly when considering that PLD use is unlikely to be the only source of noise exposure for this group. ²⁵

It is also important not to dismiss the potential impact of PLDs for those whose exposure may appear relatively low. A listener with even just 0.5 PLD DND may only be receiving 50% of an acceptable noise dose from their PLD usage—an amount unlikely to be enough to directly risk hearing damage—but they are at risk of more quickly reaching their daily exposure limit if they participate in any other noisy activities during work or leisure time. For many of these users, PLD exposure may be taking up any safety net they may have had, leaving them more vulnerable to other noise exposures (one-off or otherwise) putting them over the limit. The difficulties of devising a meaningful acceptable noise exposure guideline now that many people are exposed to multiple uncontrolled noise sources has previously been discussed. ⁹ The development of hearing health advice, particularly that which is aimed at PLD users, should take these issues into account.

This study also provides insight into the extent to which hearing difficulties may be present for PLD users. Tinnitus was reported by nearly three-quarters of all PLD users, which is comparable to that reported elsewhere. ²⁶ The absence of a significant difference in tinnitus experience between the 18- to 35-year-old risk groups may be explained in several ways. Tinnitus prevalence is known to increase with age, ²⁷ and it may be that for this younger group there is insufficient variation in age to see differences in tinnitus experience. Alternatively, it has been proposed that the presence of tinnitus can act as a motivator for reducing noise exposure. ^{25 28} In this case, many participants who have experienced tinnitus may have already reduced their exposure. A potential alternative explanation is that lower-intensity exposure from PLDs may be less likely to trigger hearing damage symptoms such as tinnitus, an outcome with potential implications for education. Short-term hearing difficulties, such as temporary threshold shifts and tinnitus (often considered warning signs of longer-term damage), are generally associated with higher-intensity exposures (e.g., nightclub attendance). As PLD usage is often associated with lower intensity of exposure, albeit often for longer durations, there may be fewer “red flags” that exposure doses are being exceeded. As such, many PLD users may be more likely to remain unaware of potential damage following exposure events. Hearing health messages should perhaps warn PLD users that the possibility of NIHL from low-volume PLD exposures is all the more insidious, requiring greater vigilance and monitoring of their exposure.

Interestingly, we did find differences between risk groups in relation to self-reported difficulty listening to speech in noise. The significant, albeit small, differences between risk groups were consistent across multiple items; that is, high-risk users were more likely to report hearing difficulties, particularly in relation to speech and conversation, compared with those with lower levels of risk. Although this study did not include objective measurement of hearing, these results suggest a potential relationship between PLD use and speech-in-noise difficulties. Such difficulties often precede clinical hearing loss as measured by pure tone audiometry and could therefore be considered an early warning sign for PLD users at risk of NIHL.

Conclusions

This study showed that the population of Australian PLD users is both large and diverse. A selection of hearing health indicators suggested that several high-risk users may be experiencing early warning signs of hearing damage. These findings highlight the importance of engaging with PLD users about their hearing health and encouraging them to monitor their exposure. In particular, this study suggests that to encourage safe listening behaviors in frequent PLD users, messages that are framed according to individual PLD listening patterns may be most effective. For example, for those using PLDs in higher noise environments, a major concern is corresponding increases in listening volumes. Encouraging lower volume settings or the use of transducers that provide greater attenuation (negating the need for high volumes) may be the most relevant strategies for these users. For those in lower volume environments, strategies that encourage users to monitor and limit their listening duration may be more appropriate.

Although the vast majority of those surveyed were listening at levels many would consider to be relatively safe, we would strongly argue that this does not negate the need for targeted and sustained hearing health messages for PLD users. The widespread use of, and related noise exposure from, PLDs means that a large proportion of the community is receiving consistent noise exposure, even at low levels, that may be increasing their risk of exceeding exposure guidelines once other noise sources are considered. According to the data, it would be disingenuous to suggest that PLD use alone places the majority of users at greater risk of NIHL. However, messages that position PLD exposure within the greater context of daily noise exposure guidelines may allow users to better manage their risk. Furthermore, the widespread usage of PLDs across all age groups means that hearing health campaigns incorporating PLD messages are likely to be relevant to a large cross section of the community. By targeting PLD use as a starting point for promotional activities, general awareness of hearing health could be increased, paving the way for more specific messages aimed at target groups engaged in other high-risk activities.

Acknowledgments

References