This book is available as an open access ebook under a CC-BY licence. Measurements, and their manipulation, have been underestimated as crucial historical forces motivating and guiding the way we think about disability. Using measurement technology as a lens, and examining in particular the measurement of hearing and breathing, this book draws together several existing discussions on disability, phenomenology, healthcare, medical practice, big data, embodiment, and emerging medical and scientific technologies around the turn of the twentieth century. These are popular topics of scholarly attention but have not, until now, been considered as interconnected topics within a single book. As such, this work connects several important, and usually separate academic subject areas and historical specialisms. The standards embedded in instrumentation created strict, but, ultimately arbitrary thresholds of what is categorised as normal and abnormal. Considering these standards from a long historical perspective reveals how these dividing lines shifted when pushed.