Fundamentals of Environmental Noise

What is the audible frequency range for humans?

• 100 Hz to 10,000 Hz

• 20,000 Hz to 40,000 Hz

• 20 Hz to 20,000 Hz

• 0 Hz to 20 Hz

What is the speed of sound in water?

• 1000 m/s

• 5000 m/s

• 1500 m/s

• 340 m/s

What does the decibel scale measure?

• Frequency of sound

• Velocity of sound

• Pressure variations in sound

• Temperature of sound

What is the threshold of hearing in decibels?

• 0 dB

• 20 dB

• 60 dB

• 130 dB

What happens when sound waves encounter an obstacle?

• They disappear

• They reflect

• They amplify

• They change frequency

What is a standing wave?

• A wave that travels in one direction

• A wave that does not move

• A wave formed by the interference of two waves

• A wave that only exists in fluids

What is the primary cause of refraction in sound waves?

• Change in temperature

• Change in frequency

• Change in medium density

• Change in amplitude

What is the effect of temperature on sound propagation?

• It increases sound speed in warm air

• It decreases sound speed in warm air

• It increases sound speed in cold air

• It has no effect

What is the characteristic impedance of a medium?

• The frequency of sound in the medium

• The ratio of acoustic pressure to particle velocity

• The density of the medium

• The speed of sound in the medium

What type of noise source is an engine classified as?

• Environmental noise

• Mechanical noise

• Acoustic noise

• Vibrational noise