Noise How it Affects Our Lives

45-75 decibels

The chapter explicitly states '45–75 decibels = range in which most people speak' and describes this as 'comfortable on the ears.' This range represents normal conversation levels that don't cause discomfort. Option A (35-50) is too low and would include very quiet sounds. Option C (75-85) extends into potentially harmful levels. Option D (85-100) is definitely in the harmful range where ear damage begins.

They expand

The chapter clearly states 'Noise causes the blood vessels in the brain to expand. It brings on pain.' This expansion of blood vessels is the physiological reason why noise causes headaches. Option A is incorrect as vessels expand, not shrink. Option C is wrong because there is a definite change in the blood vessels. Option D is false as the vessels don't stop functioning but rather react by expanding.

140 decibels

The chapter specifically mentions '140 decibels = actual pain felt.' This is the threshold where sound becomes not just harmful but physically painful to experience. Option A (100 decibels) is where hearing loss can begin, but not where pain is felt. Options B and D are not mentioned in the chapter as specific thresholds for pain.

The length of time exposed to loud noise

The chapter emphasizes 'It's the length of time of being exposed to loud noises that damages the sensitive part of the inner ear.' The rock band played at 105-115 decibels for more than eleven hours every week, showing that duration of exposure is crucial. Option A is incorrect as the music type doesn't matter, it's the volume and duration. Option C (age) is not mentioned as a factor. Option D is wrong because it's not the instruments but the loud volume and exposure time that caused damage.