Characteristics of Sound

Sound is a form of longitudinal wave produced by vibrating objects and travels through a medium (air, water, solids).

Its main characteristics are:

• • Pitch (Frequency)
  • Loudness (Amplitude)
  • Quality or Timbre (Waveform)
  • Speed of sound (Depends on medium)

1. Pitch (Depends on Frequency)

• • Pitch tells us whether a sound is “high” (shrill) or “low” (deep).
  • It depends on the frequency of vibration of the sound wave.

\( f = \dfrac{1}{T} \)

• Higher frequency → higher pitch (e.g., whistle, mosquito buzz).
• Lower frequency → lower pitch (e.g., drum beats, man’s voice).

2. Loudness (Depends on Amplitude)

• Loudness is how “strong” or “soft” a sound appears to our ears.
• It depends on the amplitude of vibration of the sound wave.
• Greater amplitude → louder sound.
• Loudness is measured in decibels (dB).
• Example: Whisper ≈ 30 dB, Conversation ≈ 60 dB, Rock Concert ≈ 120 dB.

3. Quality or Timbre (Depends on Waveform)

• Quality (or timbre) is the property of sound that allows us to distinguish between two sounds of the same pitch and loudness but produced by different sources.
• It depends on the waveform of the sound wave.
• Example: The same note played on a violin and a flute sounds different because of waveform differences.

4. Speed of Sound

• The speed of sound depends on the medium and its temperature.
• In air at room temperature (20°C): ~340 m/s.
• In water: ~1500 m/s.
• In steel: ~5000 m/s.
• Sound travels faster in solids, slower in liquids, and slowest in gases.