Loudness

Definition

Loudness is a perceptual attribute of sound that describes the intensity or volume of a sound as it is perceived by the human ear. It is a subjective measure that depends on the physical characteristics of the sound wave as well as the sensitivity of the listener's auditory system.

5 Must Know Facts For Your Next Test

1. Loudness is measured in the unit of sones, with a 1-sone sound being the reference level for a 1 kHz tone at 40 dB SPL.
2. The human ear is most sensitive to sounds in the frequency range of 1 kHz to 4 kHz, which is why these frequencies are perceived as louder at the same sound pressure level.
3. Factors that affect the perceived loudness of a sound include the sound's frequency, duration, and the listener's individual hearing sensitivity.
4. Exposure to high-intensity sounds over an extended period can lead to temporary or permanent hearing loss due to damage to the delicate structures of the inner ear.
5. The relationship between sound pressure level and perceived loudness is not linear, as the human auditory system has a compressive response to increasing sound levels.

Review Questions

• Explain how the decibel (dB) scale is used to measure the intensity of sound and its relationship to perceived loudness.
  • The decibel (dB) scale is a logarithmic scale used to measure the intensity or power of a sound. A 10 dB increase represents a tenfold increase in sound power, but the perceived loudness does not increase linearly with the dB scale. This is because the human auditory system has a compressive response to increasing sound levels, meaning that a 10 dB increase in sound pressure level does not result in a doubling of perceived loudness. The relationship between sound pressure level and perceived loudness is described by equal-loudness contours, which show the sound pressure levels required for tones of different frequencies to be perceived as equally loud.
• Describe the role of frequency in the perception of loudness and explain how the human ear's sensitivity to different frequencies affects this perception.
  • The human ear is most sensitive to sounds in the frequency range of 1 kHz to 4 kHz, which is why these frequencies are perceived as louder at the same sound pressure level. This is due to the characteristics of the human auditory system, which is more sensitive to certain frequency ranges. The perceived loudness of a sound is not only dependent on its intensity (measured in dB) but also on its frequency composition. Sounds with a higher proportion of energy in the 1 kHz to 4 kHz range will be perceived as louder than sounds with the same overall intensity but a different frequency distribution.
• Analyze the potential long-term effects of exposure to high-intensity sounds and explain the importance of hearing protection in maintaining healthy hearing.
  • Exposure to high-intensity sounds over an extended period can lead to temporary or permanent hearing loss due to damage to the delicate structures of the inner ear. This damage can occur gradually over time, as the hair cells in the cochlea become fatigued or destroyed by the intense sound waves. Prolonged exposure to loud noises, such as those encountered in industrial settings, live music events, or even prolonged use of personal audio devices at high volumes, can result in noise-induced hearing loss. To prevent this, the use of hearing protection devices, such as earplugs or noise-cancelling headphones, is crucial in maintaining healthy hearing and preventing long-term damage to the auditory system.

Related terms

Decibel (dB): The unit used to measure the intensity or power of a sound. The decibel scale is logarithmic, meaning a 10 dB increase represents a tenfold increase in sound power.

Sound Pressure Level (SPL): The physical measure of the effective pressure of a sound wave, which is closely related to the perceived loudness of the sound.

Equal-Loudness Contours: Curves on a graph that show the sound pressure levels required for tones of different frequencies to be perceived as equally loud by the human ear.