It is very important to properly assess occupational fitness for several occupations such as police officer, military personnel or fire fighter. The aim of this study was to develop a British English speech in noise (SiN) test as a tool to assess occupational auditory fitness for duty (AFFD), specifically for military. Speech tests were considered for this task as pure tone audiometry is not a good predictor of speech understanding in noisy situations. Due to high face validity, the coordinate response measure (CRM) SiN test was chosen for this study with a male speaker. To make CRM more representative for British military, emergency and traffic services the NATO phonetic alphabet was applied. The aim of the first stage of this study was to measure and equalise CRM speech intelligibility function using stationary speech-spectrum noise. Stage 2 and stage 3 of this study aimed to evaluate an adaptive version of CRM for participants with normal and impaired hearing respectively. CRM tests were performed in two conditions, ‘call sign on’ where identification of all target words was required and ‘call sign off’ where calling sign was not required. Additionally, a triple-digit test was performed for comparison. Twenty and 31 normal hearing participants took part in study 1 and 2 respectively. Twenty-two participants with a level of hearing impairment took part in study 3. The results revealed good reliability and validity for both ‘call sign on’ and ‘call sign off’ conditions. However, the author indicated that more research is needed to cover the whole range of hearing impairment and to compare performance on the test and performance in real situations. Additionally, it would be interesting to investigate how using a female speaker would influence results, especially as some research suggests that higher SNR is needed for female voices.