Listening habits of iPod users

Reducing preferred listening levels in headphones through coherent audiotactile stimulation

Using headphones may expose the listener to potentially harmful levels of sound. This study examines whether introducing tactile vibrations to the listening experience would encourage them to reduce their headphone volume. Fifteen participants adjusted their preferred listening levels for four diverse music tracks under audio-only and audiotactile conditions. Results indicated a significant decrease in preferred audio levels with added tactile stimulation. This effect was particularly significant in songs featuring a strong beat. In contrast, only a minimal effect was observed for genres such as classical music, which typically lack a pronounced beat, at higher vibration intensities. These findings suggest that integrating tactile feedback could be a viable strategy for lowering sound exposure risk.

No Reliable Association Between Recreational Noise Exposure and Threshold Sensitivity, Distortion Product Otoacoustic Emission Amplitude, or Word-in-Noise Performance in a College Student Population

OBJECTIVES

The purpose of this study was to evaluate the relationship between recreational sound exposure and potentially undiagnosed or subclinical hearing loss by assessing sound exposure history, threshold sensitivity, distortion product otoacoustic emission (DPOAE) amplitudes, and performance on the words-in-noise (WIN) test.

DESIGN

Survey data were collected from 74 adult participants (14 male and 60 female), 18 to 27 years of age, recruited via advertisements posted throughout the University of Florida campus. Of these participants, 70 completed both the survey and the additional functional test battery, and their preferred listening level was measured in a laboratory setting.

RESULTS

There were statistically significant relationships between hearing thresholds and DPOAE amplitude. In contrast, performance on the WIN was not reliably related to threshold sensitivity within this cohort with largely normal hearing. The two most common exposures included bars or dance clubs, followed by music player use. There were no statistically significant relationships between individual or composite measures of recreational sound exposure, including preferred listening level, years of music player use, number of reported sound exposures, previous impulse noise exposure, or previous noise-induced change in hearing, and functional measures including threshold, DPOAE amplitude, and WIN measures. Some subjects were highly consistent in listening level preferences, while others were more variable from song to song.

CONCLUSIONS

No reliable relationships between common recreational sound exposure or previous noise-induced changes in hearing were found during analysis of threshold sensitivity, DPOAE amplitude, or WIN performance in this cohort. However, the study sample was predominantly female and Caucasian, which limits generalizability of the results.

Listening to music with personal listening devices: monitoring the noise dose using a smartphone application

OBJECTIVES

To monitor listening habits to personal listening devices (PLDs) using a smartphone application and to compare actual listening habits to self-report data.

DESIGN

Two stages: self-report listening habits questionnaire, and real-time monitoring of listening habits through a smartphone application.

STUDY SAMPLE

Overall 117 participants aged 18-34 years (mean 25.5 years) completed the questionnaire, and of them, 40 participants (mean age: 25.2 years) were monitored for listening habits during two weeks.

RESULTS

Questionnaire main findings indicated that most of the participants reported listening for 4-7 days a week, for at least 30 min at high listening levels with volume control settings at 75-100%. Monitored data showed that actual listening days per week were 1.5-6.5 d, with mean continuous time of 1.56 h, and mean volume control setting of 7.39 (on a scale of 1-15). Eight participants (22%) were found to exceed the 100% noise dose at least once during the monitoring period. One participant (2.7%) exceeded the weekly 100% daily noise dose. Correlations between actual measurements and self-report data were low to moderate.

CONCLUSIONS

Results confirmed the feasibility of monitoring listening habits by a smartphone application, and underscore the need for such a tool to enable safe listening behaviour.

College students' personal listening device usage and knowledge

OBJECTIVE

To determine the usage and knowledge of safe limits on personal listening devices (PLD) among college students.

DESIGN

First, information on health history was collected. Second, microphone in real ear techniques determined eardrum to free-field correction factors. Third, hearing levels were evaluated and information gathered about knowledge of safe listening behaviors.

STUDY SAMPLE

180 college students participated in a one-hour session using their PLDs and earphones set to their personal preference.

RESULTS

Virtually all participants reported knowledge of hearing loss risk due to PLD use and accurately recognized their own PLD listening levels (p = .01) as either within or exceeding safe sound limits. Forty-four subjects listened at greater than 80-dBA free-field equivalent levels. Only 7% of these participants were aware of these hazardous levels and 15% of participants' exposure surpassed free-field equivalent levels normalized to eight hours.

CONCLUSIONS

Despite reported knowledge of hearing loss risk due to PLD use in virtually all college students, 1 in 4 were found to listen to their PLDs at free-field equivalent levels greater than 80-dBA, with 94% unaware of their potential risk. Further research is needed to provide accurate PLD listening information and evaluate the possibility of long term PLD intensities that surpass recommended safety levels on hearing loss in adults over time.

Extended high-frequency thresholds in college students: effects of music player use and other recreational noise

BACKGROUND

Human hearing is sensitive to sounds from as low as 20 Hz to as high as 20,000 Hz in normal ears. However, clinical tests of human hearing rarely include extended high-frequency (EHF) threshold assessments, at frequencies extending beyond 8000 Hz. EHF thresholds have been suggested for use monitoring the earliest effects of noise on the inner ear, although the clinical usefulness of EHF threshold testing is not well established for this purpose.

PURPOSE

The primary objective of this study was to determine if EHF thresholds in healthy, young adult college students vary as a function of recreational noise exposure.

RESEARCH DESIGN

A retrospective analysis of a laboratory database was conducted; all participants with both EHF threshold testing and noise history data were included. The potential for "preclinical" EHF deficits was assessed based on the measured thresholds, with the noise surveys used to estimate recreational noise exposure.

STUDY SAMPLE

EHF thresholds measured during participation in other ongoing studies were available from 87 participants (34 male and 53 female); all participants had hearing within normal clinical limits (≤25 HL) at conventional frequencies (0.25-8 kHz).

RESULTS

EHF thresholds closely matched standard reference thresholds [ANSI S3.6 (1996) Annex C]. There were statistically reliable threshold differences in participants who used music players, with 3-6 dB worse thresholds at the highest test frequencies (10-16 kHz) in participants who reported long-term use of music player devices (>5 yr), or higher listening levels during music player use.

CONCLUSIONS

It should be possible to detect small changes in high-frequency hearing for patients or participants who undergo repeated testing at periodic intervals. However, the increased population-level variability in thresholds at the highest frequencies will make it difficult to identify the presence of small but potentially important deficits in otherwise normal-hearing individuals who do not have previously established baseline data.

Digital music exposure reliably induces temporary threshold shift in normal-hearing human subjects

OBJECTIVES

One of the challenges for evaluating new otoprotective agents for potential benefit in human populations is the availability of an established clinical paradigm with real-world relevance. These studies were explicitly designed to develop a real-world digital music exposure that reliably induces temporary threshold shift (TTS) in normal-hearing human subjects.

DESIGN

Thirty-three subjects participated in studies that measured effects of digital music player use on hearing. Subjects selected either rock or pop music, which was then presented at 93 to 95 (n = 10), 98 to 100 (n = 11), or 100 to 102 (n = 12) dBA in-ear exposure level for a period of 4 hr. Audiograms and distortion product otoacoustic emissions (DPOAEs) were measured before and after music exposure. Postmusic tests were initiated 15 min, 1 hr 15 min, 2 hr 15 min, and 3 hr 15 min after the exposure ended. Additional tests were conducted the following day and 1 week later.

RESULTS

Changes in thresholds after the lowest-level exposure were difficult to distinguish from test-retest variability; however, TTS was reliably detected after higher levels of sound exposure. Changes in audiometric thresholds had a "notch" configuration, with the largest changes observed at 4 kHz (mean = 6.3 ± 3.9 dB; range = 0-14 dB). Recovery was largely complete within the first 4 hr postexposure, and all subjects showed complete recovery of both thresholds and DPOAE measures when tested 1 week postexposure.

CONCLUSIONS

These data provide insight into the variability of TTS induced by music-player use in a healthy, normal-hearing, young adult population, with music playlist, level, and duration carefully controlled. These data confirm the likelihood of temporary changes in auditory function after digital music-player use. Such data are essential for the development of a human clinical trial protocol that provides a highly powered design for evaluating novel therapeutics in human clinical trials. Care must be taken to fully inform potential subjects in future TTS studies, including protective agent evaluations, that some noise exposures have resulted in neural degeneration in animal models, even when both audiometric thresholds and DPOAE levels returned to pre-exposure values.

The challenge of detecting minimal hearing loss in audiometric surveys

PURPOSE

This tutorial provides framework and context for understanding the complex interaction of hearing measurement methodology and cohort social factors, as well as their relation to approaches to data interpretation and identification of minimal hearing loss (HL) in audiometric surveys.

METHOD

Pertinent archival studies were reviewed, and an original analysis on U.S. Centers for Disease Control and Prevention (CDC) audiometric survey data from children (ages 6-19) was performed.

CONCLUSION

The definition of an otologically normal individual, the pass-fail criterion representing the upper limit of the range of normal hearing, and the quality of the audiometry affect the percentage of persons who are falsely identified as having a minimal HL. An upper limit of normal hearing of 15 dB HL yields an unacceptably high false-positive rate, particularly when the more variable higher audiometric frequencies are examined. When air-conduction thresholds are assessed in isolation to estimate potential noise damage, the failure to exclude persons who have possible middle and external ear problems, including earwax, results in high false-positive rates. When these factors and other limitations are considered, audiograms from teens from a recent CDC survey do not show evidence consistent with widespread noise-induced HL. Suggestions are made to improve the effectiveness of pure-tone audiometry and the identification of minimal HL.