To emphasize this 'particle like' discreteness of the electromagnetic wave, the minimum strength electromagnetic wave was called a photon.
This name is similar to the names used for the entities which used to be considered particles: electron, proton, neutron etc. The discreteness of the electromagnetic wave was conjectured by Max Planck. Summary In classical physics we had two kinds of entities: particles and waves. Quantum theory brought two changes to this picture: Particles like electrons were actually waves ; these waves could be made to cancel just like electromagnetic waves.
Thus there is just one kind of entity in quantum theory, and this entity inherits features from each of the two entities in classical physics. Each object - photon or electron - has the form of a wave, and this wave exhibits the discreteness expected of particles. The amplitude of an electromagnetic wave goes in discrete steps. Show Quiz. Table of contents « Previous Next ». I hear a much more pronounced "pop" on Firefox than I do on Chrome. 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:.
And of course, ramps can also be used for an actual "fade in" or "fade out" effect, by just making them longer. Just like with frequencies though, exponential ramps often sound better than linear ones.
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. 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: setTargetAtTime.
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.
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:. 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. An ocean wave has an amplitude of 2. Weather conditions suddenly change such that the wave has an amplitude of 5. The energy transported by a wave is directly proportional to the square of the amplitude.
So whatever change occurs in the amplitude, the square of that effect impacts the energy. This means that a doubling of the amplitude results in a quadrupling of the energy. Equations are guides to thinking about how a variation in one variable affects another variable. Two waves are traveling through a container of an inert gas. Wave A has an amplitude of 0. Wave B has an amplitude of 0. Physics Tutorial.
My Cart Subscription Selection. Student Extras. See Answer Answer: C quadrupled The energy transported by a wave is directly proportional to the square of the amplitude. Sound Movement How fast does sound travel? Why does sound get weaker as it travels? Sound Spreading Sound Absorption How does sound move? Reflection Refraction Scattering Reverberation How does sound travel long distances? Sound Measurement How is sound measured? What units are used to measure sound?
How are sounds viewed and analyzed? How is hearing measured? What sounds can people hear? What sounds can animals hear? Sounds in the Sea What are common underwater sounds? How does sound in air differ from sound in water? How do people and animals use sound in the sea? Why do sounds have certain properties? How will ocean acidification affect ocean sound levels? How does marine life affect ocean sound levels? How does shipping affect ocean sound levels?
Spherical Spreading Propagation from a sound source array in the near field and far field Wave Front Propagation How does sound travel in shallow water?
How does sound travel in very shallow waters? Use of Sound How do marine animals use sound?
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