Sound — Set 4

Correct Answer: B. Wavelength only

The correct answer is 'Wavelength only'. Sound intensity is linked to energy flow through an area per time. In simple wave models, energy carried increases with the square of amplitude. That is why doubling amplitude can greatly increase loudness.

Correct Answer: D. Intensity is physical, loudness is perceived

Intensity is an objective physical measure of sound energy flow. Loudness is the human perception of that intensity and depends on the ear. Two sounds with the same intensity can feel different in loudness at different frequencies.

Correct Answer: C. Difference in timbre

Different instruments produce different sets of harmonics along with the fundamental. This changes the waveform and gives a distinct timbre or quality. Timbre helps us identify voices and instruments even at the same pitch.

Correct Answer: D. Any low-frequency sound only

Noise is generally defined as sound that is unwanted in a given context. It may be loud, irregular, or simply disturbing to the listener. Long-term noise exposure can harm hearing and health.

Correct Answer: B. Only resonance in a pipe

The correct answer is 'Only resonance in a pipe'. A sonic boom occurs when an object travels faster than the speed of sound. The pressure waves merge into a shock wave front. When this front passes a listener, it is heard as a sudden boom.

Correct Answer: B. Creating only infrasound always

The correct answer is 'Creating only infrasound always'. Animals emit sound pulses and listen to the returning echoes. The time delay and changes help them judge distance and shape. This biological method is similar in idea to sonar.

Correct Answer: C. Absorption of sound into bone only

Ultrasound waves reflect at boundaries where material properties differ. The device detects reflected signals and converts them into an image. Different tissues have different acoustic impedances, causing different reflections.

Correct Answer: D. Blood flow speed by frequency shift

Doppler ultrasound uses the Doppler effect on reflected ultrasound waves. Moving blood cells cause a frequency shift that depends on their speed. This helps assess blood flow in vessels and the heart.

Correct Answer: B. Increase room temperature greatly

Sound insulation reduces transmission by blocking vibrations and air gaps. Heavier doors and good seals reduce leakage and vibration transfer. Small gaps can greatly reduce insulation effectiveness.

Correct Answer: C. Radius, ulna, humerus

The correct answer is 'Radius, ulna, humerus'. Vibrations from the eardrum are passed to the middle ear bones. These bones are malleus, incus, and stapes. They help transfer vibrations efficiently to the inner ear.