Module 5.3: Overview of Sound Frequencies

Sound Frequencies

• Vibrating Objects: Sound waves are generated by vibrating objects (e.g., vocal cords, guitar strings). The medium's particles vibrate at a specific frequency, contributing to the sound wave's characteristics.

• Frequency Definition: The frequency of a wave refers to how often the particles of the medium vibrate as the wave passes. It is measured in hertz (Hz), where 1 Hz = 1 vibration/second.

• Sound Waves as Pressure Waves: Sound waves are pressure waves, consisting of compressions (high pressure) and rarefactions (low pressure). The frequency counts both vibrations and occurrences of compressions/rarefactions per unit time.

• Pitch Perception: Frequency directly affects pitch. Humans can hear frequencies from 20 Hz to 20,000 Hz. Frequencies below 20 Hz are inaudible (infrasound), whereas those above 20,000 Hz are also inaudible (ultrasound).

• Animal Hearing Ranges: Different species can hear varying frequencies:

  • Dogs: Up to 45,000 Hz

  • Bats: Up to 20,000 Hz

  • Elephants: As low as 5 Hz

• Musical Pitch: The sensation of detecting frequencies is termed pitch. Higher frequency results in higher pitch.

• Musical Octaves: An octave consists of 8 notes, with frequencies having a 2:1 ratio. For example, a higher C has double the frequency of a lower C.

• Harmonics: Harmonics are frequencies that are integer multiples of a fundamental frequency. The original wave is the first harmonic, with subsequent reproducing waves being the second, third, etc. Harmony in music involves the combination of these frequencies.

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This concludes the overview of sound frequencies. Further discussions will continue with sound in practical applications in the next module.