4.17 Interference of Sound Waves

True or false? The interference pattern created from 2 sound sources is similar to the interference pattern created from 2 vibrational sources in a ripple tank.

• True

• False

When standing between 2 sound sources, it's possible to hear a sound that is louder than either of the sources alone because

• both sounds are in phase, so the peaks of 1 sound wave meet with the troughs of the other sound wave

• both sounds are in phase, so the peaks of both sound waves interfere and the troughs of both waves interfere

• both sounds are out of phase, so the peaks of 1 sound wave meet with the troughs of the other sound wave

• both sounds are out of phase, so the peaks of both sound waves interfere and the troughs of both waves interfere

Select all that apply to destructive interference:

• When standing between 2 speakers, you don't hear anything even though you know both speakers are emitting sound waves.

• 2 sound waves are in phase.

• 2 sound waves are out of phase.

• The peaks of 1 sound wave encounter the troughs of the other sound wave.

• The peaks of both sound waves meet and the troughs of both sound waves meet.

When increasing the wavelengths of 2 sound sources, their interference pattern will have

• more areas of constructive and destructive interference

• less areas of constructive and destructive interference

• more areas of constructive interference but less areas of destructive interference

• less areas of constructive interference but more areas of destructive interference

Noise-cancelling headphones work because

• they absorb all sounds from your surroundings

• they create constructive interference with sounds from your surroundings

• they create destructive interference with sounds from your surroundings

• they increase the wavelength of sounds from your surroundings