Question

What is loudness?How sound measure?

Answer 1

A surprisingly complicated question.Volume -the absolutephysical property of the power of sound, ismeasured in decibels.That gives you the SPL - sound pressure level. A decibel isn’t used just for sound, it’s a ratio of properties - in this case the pressure (measured in pascals) relative to a reference. On earth, pretty much the max value for sound pressure is around 190db, although the human threshold for pain is much lower, around 130 and hearing damage can start even lower still.Loudness, however, is trickier. It’s generally a perceptivething, and the human brain does not perceive loudness evenly across the frequency spectrum or over time. Our brains are optimized to be more sensitive to sounds in the high midrange (where a lotof the “clarity” of spoken speech is) and not as much in the more extreme lows and highs. You can have a sound with a very high SPL that doesn’t sound as“loud” as you’d think because the frequency isn’t well-perceived by your brain.Dynamic range plays tricks on your brain, too. You can have two speakers each set to the same level, playing music (for example) that has thesame peak value, andone can sound louder than the other, because of the overallaverage power. However over time, the “loud” one stops seeming so loud, as the brain sort of auto-adjusts to continual loud sounds.Loudness is still sometimes roughly measured in decibels,although instead of a momentary measurement it’s an average power acrossthe spectrum - the root-mean square. These days, though, loudness is generally more accurately measured in Loudness Units (Full Scale), or LUFS. It’s similar to the RMS except it’s adjusted for human frequency perception. It’s also broken down into momentary (an individual snapshot), short term (loudness over a short window of time) and integrated (loudness over the duration of the sound).

Answer 2

Loudness is measure of how much intense the sound is heard at a particular place. it is measured in phon and to determine loudness decibel a unit is also used.