Hi, this is Wayne again with a topic “How Waves Make The Sounds We Hear”.
Hello, i’m carrie sundra of alpenglow industries, where we make frivolous circuits and handy tools for both electronics, enthusiasts and engineers. Today, i’m going to show you how you can use a waveform generator to produce different sounds. This is part of a make series on measurement and test equipment and is sponsored by liquid instruments who makes an all-in-one tool called the moku go. It performs the same functions as several of the tools that you see on my workbench behind me. You can find more info on me make and the moku go in the links in the description below when we think of waves.
We tend to think of a nice round repeating pattern like waves of sand or waves on the ocean. This type of wave is called a sine wave, a sine wave in its purest form repeats at a single frequency and when we hook it up to a speaker, it sounds like this. A triangle wave at the same frequency sounds a little different and a square wave different. Still, let’s see how we can create and analyze these waves using a moku go.
The moku go is a device that is eight different test instruments, plus a power supply in a small portable form factor. You can use it as an oscilloscope waveform generator data, logger logic, analyzer, arbitrary waveform, generator spectrum, analyzer, pid controller or frequency response generator, just plug it into your computer and a power source and you’re ready to see what’s happening inside of your circuit. Here i’m creating a single sine wave with the waveform generator and putting it through a 100 ohm resistor directly to the positive input of a small speaker. The negative input of the speaker is attached to ground, we’ll start with a one kilohertz sine wave with the waveform generator. I can adjust the frequency which adjusts the pitch of the note, and i can adjust the amplitude which adjusts the volume [ Laughter ]. We can use the oscilloscope module to get a better look at our sine wave.
Now. We can also see how it’s changing as we adjust the frequency and the amplitude as well as hear it here. We’Re adjusting frequency and now amplitude a single sine wave we hear is a pure tone, but what happens when we add two or more sine waves? Together, the waves interfere with each other, some parts add and become larger and more noticeable. Some parts subtract and become smaller and softer, and we hear all of these frequencies simultaneously.
A triangle wave is made of many sine waves added together, and you can hear the harmonics created by these interfering waves. We can also see these harmonics by using the fast fourier, transform or fft mode. An fft calculates the frequency content of a signal, and our fft graph shows us the relative magnitude of each frequency present in our waves. This is our pure sine wave at one kilohertz. You can see it’s comprised of one main frequency. This is our triangle wave at one kilohertz. You can see it’s comprised of many different frequencies. You still hear a central main pitch because the sine waves that were added decrease in amplitude as they get farther away from that main center frequency, but you’ll hear a little softening around the main note, which can actually be a bit more pleasant to the human ear. Since most sounds, we hear are indeed made of multiple frequencies. Now, what happens? If we add more sine waves with larger amplitudes, then we get a square wave which you can see has larger magnitude harmonics.
You can really hear them too square waves, sound retro, because some of the very first video games used them for sound. We can also measure the frequency content of waves directly using the spectrum analyzer. You can see the measurements correlate very well with the predictions we saw using the fft calculation, here’s our sine wave, our triangle wave and our square wave. Let’S listen to the waves again, a pure sine wave, a triangle wave and a square wave fun fact.
Sine waves are the basic building blocks of waves. You can create any shape of wave by adding them together. Human voices are just a complex bunch of sine waves. I hope you’ve learned a little bit about waves and what they sound like in our next segment.
We’Ll show you how a special type of square wave known as a pwm can be used to create motion and light for more videos about electronics, be sure to subscribe. To mink’s channel and to our alpenglow industries, channel and liquid instruments channel as well, also check out the links below for our websites and more information on the moku go see you next time. You .