Question

The loudness or softness of a sound is determined basically by its:
A. amplitude
B. waveform
C. wavelength
D. frequency

Answer 1

Hint: Loudness is caused by the vibrational pressure generated by the sound wave. Which in turn is directly proportional to the amplitude. Higher the amplitude, higher will be the loudness.

Complete step by step solution:
Loudness is basically an auditory sensation, according to which we can determine a scale for sound ranging from quiet to loud. It is the perception of pressure generated by a sound wave.
The loudness of sound is determined by basically the sensitivity of the ear and by the amplitude of the sound wave. The vibrations occurring in a source sets the wave amplitude. Thus, larger amplitude signifies more energetic vibrations and vigorous back and forth movement of molecules.
Loudness varies with the amplitude of vibration directly and is proportional to its square.
Hence, option a is the correct answer.

Additional information:
Sound levels are generally measured in decibels (dB). A normal breathing generates about 10dB. Soft whisper, when heard from a distance less than 5m generates about 30dB. During a normal conversation, humans generate about 60dB and a factory can produce on an average a loudness of 80dB. A human ear cannot hear sounds above 80dB. The pressure generated by very loud noises affects the hearing sensation of the human ear, which alters the hearing ability.

Note: Pitch and loudness often seem to be the same but they differ in their tone quality. Pith is dependent on the frequency of sound and how our ears respond to it unlike the loudness which depends on the wave energy. Pitch is the reason why every individual has a different voice quality.