Further elaboration: I’m wondering if sound waves have sizes in the same way that the electromagnetic spectrum does. Like how visible light can’t reflect off viruses because they are too small. Is it like that with sound?
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Sound waves as well as electromagnetic waves vary in amplitude (height difference between peaks and dips) as well as frequency (distance between peaks).
Yes, all waves have a wavelength. Deeper notes have a longer wavelength, that’s why subwoofers have to be so big. Higher end sound systems will send the higher pitched notes to tiny speakers called tweeters.
If you had a microscope, you could look at the grooves of a vinyl record and see the sound waves etched into the record.
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Yes, and by the way, waves aren’t ordinary matter, they can be of any size. A wave is nothing more but just a disturbance in a medium.
Yes they do! The lower the sound the longer the wavelength.
>Like how visible light can’t reflect off viruses because they are too small. Is it like that with sound?
Very much, the same thing happens with sound. What the sound waves can pass through or reflect off of depends on the size of the thing relative to the wave, just like with light.
Example: You are outside a club or bar and can hear the bass thumping, or you hear the muffled sound of music through a closed door. Why does it sound like that? Why are all the high-pitch sound waves blocked, while you can still hear the low-pitch parts through the wall or door? In both those cases, the low-pitch waves have a wavelength that is big compared to the door or wall thickness, so they can pass through. High-pitch soundwaves are “smaller” (aka shorter wavelength) than the wall’s thickness, so they get absorbed or reflected and don’t make it to you on the other side.
Yes, all waves (including sound waves) have “sizes”, but “sizes” needs some unpacking here.
A wave is a periodic disturbance in… *something*. The wave’s “amplitude” is the magnitude of the maximum disturbance from the *something’s* mean value. The wave’s “wavelength” is the distance between the peaks of the disturbance in the *something*. Both of these could be called measures of the wave’s “size”. (The other defining characteristics of a wave are its frequency and its speed, but these can’t really be described as the “size” of the wave, so I’ll ignore these.)
I’ll take three cases, getting less intuitive as we go.
In **water waves**, the disturbance (in… water) is at right-angles to the wave’s direction of travel. The amplitude is the maximum distance (in metres) between the peak height of the water and the water’s mean height. The wavelength is the distance (in metres) between peaks.
In **sound waves**, the disturbance is a pressure wave – periodic compression in the packing of the constituent particles of some medium (air, water, solids) where the disturbance is in the same direction as the wave’s direction of travel. (The usual analogy is to a Slinky being pushed to get a compression in the coils travelling along the toy’s length.) The simplest and most direct measure of amplitude for sound waves is the difference in pressure of the air (or other medium) between its maximum and mean levels as the pulse of pressure passes. (For the Slinky, it would be the increased packing density of the coils.) With sound, we normally express amplitude indirectly – as a measure of loudness (in decibels). The wavelength is the distance (in metres) between points of maximum compression in the medium.
In **electromagnetic waves (e.g. light)**, things get trickier, because we’re no longer talking about a disturbance in a physical medium; we’re now talking about a disturbance in an electric field. (There’s also a paired magnetic field, but we can stick to the electric field for this example.) As with water waves, the disturbance is at right-angles to the wave’s direction of travel and the wavelength is the distance (in metres) between peaks in the disturbance. The amplitude of the wave is the maximum disturbance in the electric field. This is most directly measured in newtons per coulomb, or in volts per metre. For light, an increase in amplitude results in a higher intensity (brightness) of the light (measured in candelas).
(Edit to clarify section on amplitude of sound waves.)
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