NCERT Solutions for Class 9 Science Chapter 12
Important NCERT Questions
Sound
NCERT Books for Session 2022-2023
CBSE Board and UP Board
Intext Questions
Page No-166
Questions No-1
Which wave property determines
(a) loudness,
(b) pitch?
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(a) Loudness: Amplitude
– Explanation: Loudness refers to the perceived volume or strength of a sound. It is intricately linked to the amplitude of the sound wave. Amplitude represents the peak height of the sound wave, indicating the magnitude of its vibrations and the energy carried by the wave.
– Relation to Loudness: When a sound wave has a higher amplitude, it causes more pronounced variations in air pressure. As a result, our ears perceive these more forceful vibrations as louder sounds. Hence, louder sounds are associated with sound waves that have larger amplitudes.
(b) Pitch: Frequency
– Explanation: Pitch describes the perceived frequency or highness/lowness of a sound. It is determined by the frequency of the sound wave, which represents the number of oscillations or cycles per unit of time.
– Relation to Pitch: Sound waves with higher frequencies produce higher-pitched sounds, while those with lower frequencies create lower-pitched sounds. For instance, a high-pitched whistle has a high-frequency sound wave with rapid oscillations, whereas a low-pitched drumbeat has a lower frequency with slower oscillations.
In summary, loudness is closely tied to the amplitude of a sound wave: larger amplitudes lead to louder sounds. Conversely, pitch is intricately linked to the frequency of the sound wave: higher frequencies result in higher-pitched sounds, while lower frequencies produce lower-pitched sounds. These two properties—amplitude and frequency—play pivotal roles in shaping our perception of sound characteristics like loudness and pitch.