Evaluation of sound localization and speech recognition with a sound enhancing connection tube for non-linear earplugs

Abstract

Noise-induced hearing-loss (NIHL) can occur when an individual is exposed to high-intensity acoustic stimuli. To prevent NIHL, individuals may use non-linear-earplugs (NLEPs) that provide some attenuation, substantially within the frequency range of 1–4 kHz. Wearing NLEPs can reduce speech recognition as well as sound localization. As weapon noise is mostly present in the 1–4 kHz range and is therefore partly attenuated by NLEPs, there is a downside to the reduced ability of a soldier using them to localize the source of enemy gunfire. A perforated sound-enhancing connection tube (SECT) was designed to connect to NLEPs for improving the user’s ability to localize sound and speech recognition in noise while retaining the NLEPs's noise attenuation benefits of protecting one's hearing. A previous experiment examined the effect of the SECT with NLEPs on the Head Related Transfer Function (HRTF) of a head-and-torso-simulator (HATS) (manikin). The obtained HRTF demonstrated a 3–10 dB difference in the 1–4 kHz frequency range relative to the HRTF with the NLEPs alone, implying that sound stimuli in that frequency range might be more audible to the user. The presented work will demonstrate the speech recognition in noise and sound localization of participants when using the SECT with NLEPs.