What is meant by loudness?
Loudness is the human impression of the strength of a sound. The loudness of a noise does not necessarily correlate with its sound level. Loudness level of any sound, in phons, is the decibel level of an equally loud 1kHz tone, heard binaurally by an otologically normal listener. Historically, it was with a little reluctance that a simple frequency weighting “sound level meter” was accepted as giving a satisfactory approximation to loudness. The ear senses noise on a different basis than simple energy summation, and this can lead to discrepancy between the loudness of certain repetitive sounds and their sound level. A 10dB sound level increase is perceived to be about “twice as loud” in many cases.
Loudness: Loudness is one of the more difficult aspects of domestic acoustics to learn and understand. I will try me best to get things straight. Loudness is the human impression of the strength of a sound. The loudness of a noise does not always correlate with its sound level. A-Weighting: The A-weighting scale attempts to balance the electronic pass band of a sound level meter to respond to sound at various frequencies as the human ear actually hears it after passing through the eardrum, the middle and into the inner ear (cochlea). Loudness Weighting: The actual weighting curve for the human ear is much more complex than the simplistic A-weightng curve. The ear canal creates a resonance around 4,000 Hz, and the low frequency response depends on sound level, being flatter for the highest sound levels, and cutting off rapidly at low frequencies for low sound levels. Phons: The loudness level of any sound, in phons, is the decibel level of an equally loud 1kHz tone, heard binaurally by
