What is Sound Characteristics And Propagation of Sound
Introduction
Sound is a fundamental phenomenon in physics and daily life, studied extensively in competitive exams like ETEA and NTS. This article covers the basic definition, key characteristics, and how sound propagates through various media.
Definition of Sound
Sound is a mechanical wave produced by vibrating objects, transmitted through a medium (solid, liquid, or gas) as successive compressions and rarefactions of the particles.
Characteristics of Sound
Pitch
Pitch refers to how high or low a sound appears, determined by the frequency of the sound wave. Higher frequency → higher pitch (e.g., a whistle), lower frequency → lower pitch (e.g., a bass drum).
Loudness
Loudness is the perceived intensity of sound, related to the amplitude of the wave. Greater amplitude → louder sound. Measured in decibels (dB).
Timbre (Quality)
Timbre, or quality, distinguishes different sound sources with the same pitch and loudness. It depends on the waveform shape and presence of harmonics.
Propagation of Sound
Mediums of Propagation
Sound requires a material medium to travel. It moves fastest in solids, slower in liquids, and slowest in gases due to particle spacing and elasticity.
Speed of Sound
Approximate speeds at 20 °C:
| Medium | Speed (m/s) |
|---|---|
| Air | 343 |
| Water | 1482 |
| Steel | 5960 |
Factors Affecting Speed
- Temperature: Higher temperature → faster speed in gases.
- Density & Elasticity: More elastic mediums transmit sound faster.
- Humidity: Increased humidity slightly increases speed in air.
ETEA, NTS & Other Exam Tips
- Memorize key terms: compression, rarefaction, frequency, amplitude.
- Practice numerical problems on wave speed and time of flight.
- Understand diagrams of longitudinal waves.
- Review past papers for question patterns on characteristics and propagation.
Conclusion
Sound’s properties and propagation principles are vital in physics curricula and exam syllabi. Mastering definitions, characteristics, and formulas will help you excel in ETEA, NTS, and related competitive exams.
