A-weighted sound level approximates perceived loudness only crudely, yet remains the noise-measurement standard.

Evidence

In order to have a better, yet relatively simple, measure of the perceived level of sound, the concept of sound level is defined as a measure that is weighted with frequency so that the level roughly approximates the frequency sensitivity of hearing. Four different weighting curves are defined: A, B, C, and D, as shown in Figure 9.3. The A-weighted sound level is commonly used in noise measurements to characterize the perceived level and the risk of hearing loss. The A weighting slightly emphasizes the levels at mid frequencies and attenuates them at low and high frequencies. When the weighting curve is compared with the inverted equal-loudness curves, it is easy to see that the A weighting is just a very rough estimate. Technical simplicity and extensive use in practice are its advantages. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 988

Categorization

Category: Definitional Content

• DEFINE: Explains what A-weighting actually does and its acknowledged crudeness as an approximation of perceived loudness.
• XREF: Connects to noise regulation standards and hearing-loss risk measurement used in the One Square Inch of Silence noise-exposure material.

Related

• A-weighting is recommended for all sound levels despite fitting low levels best (similarity 0.93)
• A-weighted decibels are a rough practical approximation of perceived loudness (similarity 0.92)
• Loudness meters use frequency weightings as a compromise because ear response varies with level (similarity 0.90)
• A-weighting can miss dominant low-frequency energy in broadband sounds (similarity 0.90)
• ISO standardized loudness-based noise metrics because A-weighting proved inadequate (similarity 0.89)
• Loudness scales with frequency squared, requiring large amplitude at low frequencies (similarity 0.88)
• Loudness perception is logarithmic, which is why decibel scales fit hearing so well. (similarity 0.86)
• A-weighting, the legal noise standard, rests on dated single-frequency measurements (similarity 0.86)
• A-weighted decibels better predict hearing damage than unweighted sound pressure level. (similarity 0.85)
• The A-weighting filter is now standard for all sound levels for consistency (similarity 0.84)
• Perceived loudness meters must weight frequencies as a compromise across sound levels. (similarity 0.84)
• A-weighting won general acceptance while B-weighting was abandoned (similarity 0.83)
• A simple high-pass filter can replace elaborate loudness models (similarity 0.83)
• A-weighted dB values misrepresent perceived loudness for complex sounds. (similarity 0.83)
• Outer and middle ear damage changes the loudness frequency balance (similarity 0.82)