Measurement Method for Speech Intelligibility of Firefighter Radios

In the event of a large-scale fire, not only the fire department but also multiple government agencies collaborate in response. For effective communication, secure radios capable of data transmission are utilised. However, when firefighters use radios in fire suppression environments, intelligibility is often compromised due to background noise as well as the presence of water and other environmental factors. Therefore, evaluating the speech intelligibility of firefighter radios should take into account not only ambient noise but also the effects of water exposure. This study compares the speech intelligibility of conventional radios and firefighter radios with data transmission capabilities. The impact of varying noise levels on speech intelligibility was also examined. Conventional radios were found to generate a sound level of 80 dB, with a Speech Transmission Index (STI) exceeding 0.8. In contrast, firefighter radios with data transmission capabilities produced relatively lower sound pressure levels. Additionally, the presence of water used in fire suppression was found to reduce both sound pressure levels and speech intelligibility. Future research should focus on standardising measurement methods for assessing the speech intelligibility of firefighter radios, considering the noise characteristics and water exposure conditions specific to fire suppression environments.