My dad was an audiologist and worked for many years with children with cochlear implants. I remember in the 90s him bringing a laptop home with software that tested otoacoustic emissions via a microphone/earbud combo. Later I met one of his colleagues from that time who, whilst working full time and with a large young family, obtained a phd in using this tech to test newborn hearing. That work has been the basis for the UK’s national newborn hearing screening service for decades now, helping to catch issues early where the most impact can be made. I’m really in awe of this profession - it’s pretty out of sight for many but makes a huge difference.