Headphones originated as noise isolation for radio operators

Evidence

Another way to transform an electrical audio signal into acoustic sound is by using headphones (also called earphones) (Borwick, 2001). Headphones were designed initially to isolate radio-communication operators from external acoustic noise. However, they are used nowadays in portable personal audio equipment and high fidelity systems. Furthermore, they are also important for research purposes, especially when the sound in each ear must be controlled individually. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 476

Categorization

• XREF: Connects to the broader theme of individualizing acoustic control for research (binaural/HRTF audio) — relevant to the reader’s interest in acoustic communication applications. — connects to: Good noise isolation reduces preferred playback levels and hearing damage; Modern headphones can prevent rather than cause hearing loss; High ambient noise forces listeners to raise volume toward hearing-loss levels — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2562
• corroborated: 3 independent passages support this claim — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 476

Broader Connections

• Modern headphones can prevent rather than cause hearing loss #expands (0.72)
• Good noise isolation reduces preferred playback levels and hearing damage #complicates (0.70)
• High ambient noise forces listeners to raise volume toward hearing-loss levels #expands (0.70) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2562