Andrew Crawford is well known for his studies of the mechanism of hearing in vertebrates. In 1976, Andrew and Robert Fettiplace developed a method of recording the electrical responses of hair cells in the isolated cochlea of reptiles. These remarkable experiments, which were the first to give extensive quantitative records from auditory receptors, showed that each hair cell is sharply tuned to a characteristic frequency and that much of the frequency selectivity in the turtle’s ear can be attributed to electrical resonance in the hair cell membrane. Later work proved that nerve impulses in efferent nerve fibres reduced the sensitivity and sharpness of tuning of hair cells by increasing the electrical damping. Another important result, obtained by imposing mechanical displacements, was the direct demonstration that basilar membrane vibrations of about 0.1 nanometres can be detected by the cochlea and correspond to the behavioural threshold of the animal. Andrew has also published a series of important papers on neuromuscular transmission in frogs and crabs.