An interventional study of In-ear Air Conduction Headphones and Open-ear Bone Conduction Headphones in Noise Exposure, Preferred Loudness Level and Normal Hearing, sponsored by Second Affiliated Hospital, Zhejiang University, School of Medicine. Recruiting at 1 site in China. Open to participants aged 18 Years to 35 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-11-12.
Sponsored by Second Affiliated Hospital, Zhejiang University, School of Medicine · Not applicable, Interventional, and Basic science
Open-ear bone conduction headphones are increasingly used as an alternative to conventional in-ear air conduction headphones. Because bone conduction headphones do not block the ear canal, it is often assumed that users may be more affected by background noise and may increase their listening volume to hear music clearly. However, direct evidence supporting this assumption is limited.
This study aims to compare self-adjusted listening volumes between bone conduction and air conduction headphones under different background noise conditions. Approximately 32 healthy adults aged 18-35 years with normal hearing will participate in the study. Each participant will test three listening conditions: in-ear air conduction headphones, open-ear bone conduction headphones, and bone conduction headphones combined with ear occlusion. Each condition will be tested in a quiet environment and under four levels of background noise (30, 40, 50, and 60 dB(A)).
Participants will listen to the same music and adjust the volume themselves to a level they consider comfortable and clear for prolonged listening. The selected listening volume and adjustment behavior will be recorded and compared across headphone types and noise conditions.
The findings may provide behavioral evidence on whether open-ear bone conduction headphone users choose higher listening volumes in noisy environments compared with users of conventional in-ear air conduction headphones, helping to improve understanding of potential noise exposure and hearing safety.
Second Affiliated Hospital, Zhejiang University, School of Medicine is the lead sponsor of 100 studies on the registry; 68 are open to participants now.
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Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will first use in-ear air conduction headphones (AC), followed by open-ear bone conduction headphones (BC), and then bone conduction headphones combined with ear occlusion (BC+Occlusion). Each listening condition will be tested in a quiet environment and under background noise levels of 30, 40, 50, and 60 dB(A). Participants will independently adjust the music volume to a level they consider comfortable and clear.
Behavioral: In-ear Air Conduction Headphones · Behavioral: Open-ear Bone Conduction Headphones · Behavioral: Bone Conduction Headphones with Ear Occlusion
Participants will first use open-ear bone conduction headphones (BC), followed by in-ear air conduction headphones (AC), and then bone conduction headphones combined with ear occlusion (BC+Occlusion). Each listening condition will be tested in a quiet environment and under background noise levels of 30, 40, 50, and 60 dB(A). Participants will independently adjust the music volume to a level they consider comfortable and clear.
Behavioral: In-ear Air Conduction Headphones · Behavioral: Open-ear Bone Conduction Headphones · Behavioral: Bone Conduction Headphones with Ear Occlusion
Participants will wear in-ear air conduction headphones and independently adjust the music volume to a level they consider comfortable and clear for prolonged listening. Testing will be conducted in a quiet environment and under background noise levels of 30, 40, 50, and 60 dB(A). The final selected volume and adjustment behavior will be recorded.
Participants will wear open-ear bone conduction headphones and independently adjust the music volume to a level they consider comfortable and clear for prolonged listening. Testing will be conducted in a quiet environment and under background noise levels of 30, 40, 50, and 60 dB(A). The final selected volume and adjustment behavior will be recorded.
Participants will wear open-ear bone conduction headphones while simultaneously inserting in-ear air conduction headphones into both ear canals to create an ear occlusion condition. Music will be delivered exclusively through the bone conduction headphones. Participants will independently adjust the music volume to a level they consider comfortable and clear for prolonged listening. Testing will be conducted in a quiet environment and under background noise levels of 30, 40, 50, and 60 dB(A). The final selected volume and adjustment behavior will be recorded.
Change in Self-Adjusted Listening Volume From Quiet to 60 dB(A) Background Noise Levels
The change in final self-adjusted music volume from the quiet condition to the 60 dB(A) background noise condition will be calculated separately for each headphone condition (in-ear air conduction headphones \[AC\] and open-ear bone conduction headphones \[BC\]). The change will be calculated as the final volume at 60 dB(A) minus the final volume in the quiet condition. The differences in volume change among the two headphone conditions will be compared.
Time frame: During the study visit (approximately 1-2 hours).
Change in Self-Adjusted Listening Volume From Quiet to 30, 40, and 50 dB(A) Background Noise Levels
The change in final self-adjusted music volume from the quiet condition to each background noise level (30, 40, and 50 dB(A)) will be calculated separately for in-ear air conduction headphones (AC) and open-ear bone conduction headphones (BC). The change will be calculated as the final volume at each noise level minus the final volume in the quiet condition. The volume changes between the two headphone conditions will be compared at each noise level.
Time frame: During the study visit (approximately 1-2 hours).
Final Self-Adjusted Listening Volume at Different Background Noise Levels
The final self-adjusted music volume at quiet condition, 30, 40, 50, and 60 dB(A) background noise levels will be recorded and compared between AC and BC headphones.
Time frame: During the study visit (approximately 1-2 hours).
Number of Volume Adjustments
The total number of individual volume adjustments made by each participant during each test will be recorded and compared between AC and BC headphones under different background noise conditions.
Time frame: During the study visit (approximately 1-2 hours).
Total Time Required for Volume Adjustment
The total time from the beginning of volume adjustment to reaching the final self-adjusted listening volume will be recorded and compared between AC and BC headphones under different background noise conditions.
Time frame: During the study visit (approximately 1-2 hours).
Cumulative Magnitude of Volume Adjustments
The cumulative magnitude of volume adjustments during each test will be calculated as the sum of the absolute values of all individual volume changes, regardless of the direction of adjustment, and compared between AC and BC headphones under different background noise conditions.
Time frame: During the study visit (approximately 1-2 hours).
Subjective Perception of Vibration During Bone Conduction Headphone Use
Participants will be asked whether they perceive vibration while using bone conduction headphones at their final selected listening volume. The presence or absence of perceived vibration will be recorded under different background noise conditions.
Time frame: During the study visit (approximately 1-2 hours).
Change in Self-Adjusted Listening Volume With Ear Occlusion During Bone Conduction Listening
The change in final self-adjusted music volume from the quiet condition to each background noise condition (30, 40, 50, and 60 dB(A)) will be calculated when participants use bone conduction headphones with bilateral ear occlusion (BC+Occlusion). The results will be compared with those obtained using bone conduction headphones without ear occlusion (BC) to evaluate the effect of ear occlusion on noise-induced volume adjustment.
Time frame: During the study visit (approximately 1-2 hours).
Final Self-Adjusted Listening Volume With Ear Occlusion During Bone Conduction Listening
The final self-adjusted music volume under quiet and background noise conditions (30, 40, 50, and 60 dB(A)) will be recorded during bone conduction headphone use with bilateral ear occlusion (BC+Occlusion) and compared with the corresponding BC condition without ear occlusion.
Time frame: Time Frame: During the study visit (approximately 1-2 hours).
Start is estimated for Nov 2026; primary completion for Jun 2027, 7 months later.
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Second Affiliated Hospital, Zhejiang University, School of Medicine →