Acoustics and Sound Waves

Correct Answer: Because crystal detector fails at microwave frequencies

Stage 4 (deep sleep/slow-wave sleep) has the highest arousal threshold. Waking from it causes sleep inertia - confusion, grogginess, disorientation. Stage 1 is light sleep (easy to awaken, aware). Stage 2 has sleep spindles but moderate arousal threshold. Stage 3 is also deep sleep but Stage 4 is the deepest, hence maximal confusion upon abrupt awakening.

Hearing aids amplify sound waves to help overcome conductive hearing loss, which occurs when sound cannot efficiently pass through the outer and middle ear. In nerve (sensorineural) deafness, the damage is to the inner ear or auditory nerve itself, so amplifying sound cannot help because the neural pathway for transmitting sound signals to the brain is impaired.

Yes, this is the correct answer. Sound needs medium to travel, which is not present in vacuum.

It is the larger of the two muscles of the tympanic cavity. Its role is to dampen sounds, such as those produced from chewing.

Resonant sounds are low pitched, hollow sounds heard over normal lung tissue.

Decibel (dB) is a unit that is used to measure intensity of sound level.

Sound travels through the ear in this sequence: outer ear collects sound waves, ear canal directs them to the eardrum, eardrum vibrations are transmitted through the middle ear to the inner ear, and finally the inner ear converts vibrations to electrical signals for the brain. Option D correctly lists this order.

Sound cannot travel through vacuum.

The standard audible frequency range for healthy humans is 20 Hz to 20,000 Hz (20 kHz). Option A is too narrow (only 200 Hz), option B extends only to 2000 Hz (still too limited), and option D starts at 30 Hz and extends to 30,000 Hz (incorrect range).

A rocket flying through space wil be silent because sound needs a medium to travel and cannot travel through the vacuum of space.

Sound is a mechanical wave that requires a medium to propagate and can travel through all three states of matter: solids, liquids, and gases. Options A, B, and C incorrectly limit sound to only one medium. Sound travels fastest in solids, slower in liquids, and slowest in gases.

When air is sucked from a tumbler (creating partial vacuum), there are fewer air molecules to vibrate and transmit sound waves. This reduces the amplitude of sound waves reaching your ear, making the sound softer or less loud. The loudness decreases due to reduced medium density.

Low frequency (bass) sounds are produced when vocal cords are thick and relaxed. Thicker cords vibrate more slowly, producing lower frequencies. Relaxed cords allow for slower vibration rates compared to taut cords, which produce higher frequencies. This is why male voices (with thicker, longer cords) typically have lower pitches.

Sound requires a material medium (solid, liquid, or gas) to propagate as mechanical waves. The Moon has virtually no atmosphere, meaning there is no medium for sound waves to travel through.