Final answer:
d) Cotton balls Cotton balls are not an acceptable form of hearing protection. Effective types include earplugs, earmuffs, and noise-cancelling headphones, which use destructive interference to reduce external noise.
Step-by-step explanation:
The form of hearing protection that is NOT acceptable for effective noise reduction is cotton balls. The adequate forms of hearing protection include earplugs, earmuffs, and noise-cancelling headphones. Earplugs and earmuffs provide a physical barrier to incoming noise, reducing its intensity before it reaches the eardrums. In contrast, noise-cancelling headphones use a sophisticated technology called destructive interference to create a sound wave exactly opposite to the incoming sound, effectively cancelling it out. This technology can be more effective than simple passive attenuation at protecting against noise exposure. It’s important to use proper hearing protection, as exposure to sounds above 85 decibels (dB) for prolonged periods can result in hearing damage.
Noise-canceling headphones differ from standard headphones used to block outside sounds in that they use destructive interference to reduce the loudness of outside sounds. Standard headphones only block sound waves with a physical barrier, while noise-canceling headphones create a sound wave that is exactly opposite to the incoming sound, cancelling it out. This technology makes noise-canceling headphones more effective than simple passive attenuation used in most ear protection.