The invention relates to a test to measure the ability of a subject to discriminate between speech sounds. The speech sounds may be selected from the worlds most widely spoken languages to enable the test to be carried out irrespective of the language spoken by the subject. Speech sounds may be presented in sequences, such as triplets. The subject would then be required to detect which speech sound in each sequence is different from the others. The test may be provided on a computer or similar device, in an embodiment a tablet computer, enabling the subject to conduct a self-assessment. The test may be performed on hearing aid users to determine the likelihood of a hearing aid user obtaining better test results after receiving one or two cochlear implants.