Explain the relationship between amplitude and loudness

waves - Relationship between amplitude and loudness (again)? - Sound Design Stack Exchange

explain the relationship between amplitude and loudness

Loudness is typically measured in decibels, dB. In these units, the relationship is. LI=10log(II0). where LI is the sound intensity level relative to. What is the relationship between amplitude and loudness??? The larger an amplitude of a wave the louder the sound and the lower the. If you decrease the amplitude, you are making the sound softer. Characteristics that scientists use to describe sound, such as amplitude, can be.

In any case it's better to avoid instant changes in gain because they may present a problem. For this reason, we want to use a ramp even for loudness changes that should sound instantaneous. If we use a ramp duration of something like 30 milliseconds, we will eliminate the pops but still get a seemingly instant change, which is exactly what we want: But the problem with exponential ramps is that they don't really work when zero values are involved, as they are if we want to fully fade something in or out.

This is because of the way the exponential formula is defined in the Web Audio spec. The source value is used as a divisor which means there would be a division by zero.

Relation between loudness,amplitude and pitch,frequency? Sound-Science - Class 8

We could use fades with numbers very close to bot not exactly zero to work around this, but we can also use an alternative exponential ramping function that AudioParam provides: It uses a different formula and requires a bit more work because you need to figure out an additional "time constant" argument. But with a suitable value we get a ramp that we perceive as a very smooth fade: We've seen how the perceived loudness of a sound can be controlled by changing its amplitude.

But usually when people talk about loudness, they use a different measure: They talk about how many decibels the volume level of a sound is. A tech rider for the band Sunn O mentions they operate at "dB on stage".

The Fundamentals of Amplitude and Loudness

They play some fantastically loud shows. Decibels indeed measure the loudness of sounds and it is often useful to use them in Web Audio applications as well. But there are two key points to understand about how decibel scales work: Decibels are always a relative measure. There's an exponential relationship between the amplitude of a sound wave and its loudness in decibels.

explain the relationship between amplitude and loudness

When you say how loud an audio signal is in decibels, you're always comparing it to some other audio signal. One signal is 80dB relative to something else.

So theoretically there's an infinite amount of different decibel scales you could use, because you could compare any two possible sound signals with each other. If this was all there was to it, it would be very difficult to talk about loudness though. To talk about loudness in a meaningful way you need shared reference points. Its reference sound is a very quiet one: The lower threshold of human hearing, or, "roughly the sound of a mosquito flying 3 m away".

So effectively, when we want to talk about loudness in decibels, we always compare it to the sound that mosquito at the other end of the room is making. In Web Audio, and digital audio in general, this isn't quite as useful a measurement as you might think though. There is no way for us to make a sound in Web Audio that's, say, "ten times louder than a mosquite flying 3 m away". This is because the sound volume that a user actually hears depends on the air pressure changes caused by soundwaves reaching their eardrums.

To begin with, pretty much every laptop and smartphone in the world has a "master volume" control which impacts how loud everything is. Not only that, but the volume a user perceives also depends on how far away from their speakers they happen to be sitting. That's because soundwaves in the air become weaker the farther they get.

Because of external factors such as master volume controls, we cannot do much about the actual perceived volume in Web Audio. All we can really do in Web Audio is measure wave amplitudes and let the user's audio system determine how loud they actually end up being.

But what we can do is define how loud our sounds are relative to each other. For this purpose, a useful decibel measurement for us is Decibels relative to full scale dBFSwhich is anchored on the maximum peak level possible in the system.

As we already discussed, in Web Audio our signal peak level is 1, since that is the highest sample value we can have.

explain the relationship between amplitude and loudness

This is our anchoring point for dbFS. The wave coming from an OscillatorNode is at the peak level already, so its loudness is exactly 1 dBFS. But what about levels other than 1?

How frequency and amplitude affect pitch and loudness respectively

What is our dBFS scale? The Relationship Between Amplitude and Decibels In the previous article we established that there's an exponential relationship between the frequency of a soundwave and the pitch that we hear when we listen to it. Interestingly enough, there's a very similar exponential relationship that relates to loudness: When we make a sound a certain amount of decibels louder, the underlying sound wave's peak amplitude grows exponentially.

explain the relationship between amplitude and loudness

In dB SPL the mosquito three meters away a0 is 0. We can also flip the formula around, so that if we know the desired decibel level dBFSwe can get the corresponding amplitude from that: Or, conversely, as we increase the amplitude, the decibel level grows more slowly than that.

We need a large change in amplitude to get an audible difference in the sound level. And what's with the magic number 20? Amplitude and Loudness So decibels express amplitude or loudness levels as a value relative to some reference value or beginning value. For example, dBSPL by itself is meaningless. Most people begin to hear a slight change in level at plus or minus 2dB to 3dB.

A 6dB change is perceived as a significant change in level and 10dB to 12dB can be heard as a doubling or halving of loudness. Having a good understanding of these ideas will speed up your mixing process substantially by fine-tuning your isomorphic mapping abilities.

explain the relationship between amplitude and loudness

That is, your knowledge of what sonic effects will be created by a particular slider or knob before you make the adjustment. A Pascal is an absolute unit that can be measured. But saying that The Who concert in broke the world record for loudness at dBSPL at a distance of feet from the stage is meaningless, unless you compare that to 0dBSPL at the same distance, which is the Threshold of Human Hearing. That is the quietest sound a human being with undamaged hearing can detect given a test tone of Hz.

This perceived level is subject to environmental issues like temperature and is also frequency dependent. The Fletcher Munson Equal-Loudness contours are a graphical representation of our sensitivity to various parts of the frequency spectrum.

explain the relationship between amplitude and loudness

Each line represents an equal perceived loudness level at various frequencies. From these contours, compiled via extensive laboratory testing, we can deduce that we are most sensitive to frequencies between roughly 1kHz and 6kHz, and must adjust levels upward in lower and higher frequencies to attain the same perceived loudness.

What is crucial to comprehend, is that the contours change significantly as the reference value or overall level goes up. Take that same mix and listen to it at a very soft level and it will sound bass-light. Likewise, mixing at very low levels will result in overbearing bass at loud levels, because of overcompensation for your lack of sensitivity in the low end at those softer levels.

So what to do? Many believe that mixing at moderate levels is a good practice, somewhere between 65 and 75dBSPL is a good place to start. Then audition your mix at various levels to see how well it translates.

Sound - Characteristics Of Sound - Examples & Diagrams - Lecture 10

While many home stereo systems have a loudness control which is intended to compensate for light bass in low-level listening situations, you cannot count on your listener either having this control, knowing what it does or how to use it even if they do.

Of course, if your mix is destined for the ears of a qualified Mastering Engineerthey will be well aware of these issues. Common Amplitude Measurements and Loudness I am going to resist the urge to put formulas in this article based on my teaching experience and the mathematical anxiety many people needlessly impose on themselves. Instead, I have assembled a list of amplitude measurements you might come across in equipment specifications, plugins, and audio applications.

Weighted filters are used to adjust for human hearing sensitivity across the frequency spectrum and include: Curves A, B and C are for low, medium and high loudness sounds.

D is specifically for measuring very loud aircraft noise. For instance, while dBFS level might be at 0dBFS, it is still possible to have a dBTP above zero since the natural curve of the measured waveform may tend to rise above zero between samples. This is undesirable and in fact not allowable for certain deliverables, particularly in broadcast environments.