Effectiveness of earplugs and noise cancelling headphones to improve turboprop acoustic comfort.

Participants sat in a grounded cabin, not a flying aircraft. There was no engine vibration, the sound came from a single speaker behind them, and in a real flight sound and vibration can amplify each other, which could change the results. Each device was worn for only 45 minutes, and discomfort in several areas increased over that time, so longer flights might produce different results. Only one headphone model and one earplug model were tested. The paper notes that using an inappropriate headphone model may even increase sound levels and that a different earplug could suit passengers better. Earplug insertion was not checked by the researchers, only self-checked by participants, and a poor fit can give almost no attenuation. The participants were young (average age 27) and all had normal hearing; the paper notes that hearing sensitivity declines with age, so older passengers may respond differently. The analysis corrected for multiple comparisons, but the authors report and discuss mainly the uncorrected results, so the earplug findings and the headphone-over-earplug comfort advantage do not hold once that correction is applied. Only 22 of the 24 participants completed the preference question. Everything measured was subjective. The paper itself suggests adding an objective measure of the sound level inside the protection. Participants had no set task and social interactions were not recorded, and the paper notes that what a passenger is doing can change how much noise bothers them.

The experiment was funded by the Clean Sky 2 Joint Undertaking, an EU aviation research programme, under grant agreement 945583 (ComfDemo). One author was supported by a China Scholarship Council scholarship. The authors declared no potential conflicts of interest. The study names specific commercial products and recommends that airlines provide tested headphone models with instructions.

Do not read this as evidence for giving earplugs or noise-cancelling headphones to your patients. The participants were healthy adults rating their comfort as airline passengers sitting in a grounded cabin, and no clinical, functional or communication outcome was measured. The earplug benefits were also only significant before the analysis was adjusted for multiple comparisons, so they may not be real.