Exposure to high level noise (190 dB SPL) may cause the earmuff to vibrate off the external ear causing a leak which would allow hazardous exposure to dangerous levels of noise. In loud enough environments, the ear canal can vibrate, causing the air trapped inside the earcup to vibrate as well. This typically only occurs with low frequency noise, but can reduce the effectiveness of the hearing protection device. Technology in earmuffs is developing and shows promise in reducing the effects of airflow vibrations in the ear muffs.