The Science of Sound: Part III

Have you ever wondered what your vocal cords look like? Why do some people sound the way they do? Today we will dig into those topics during the third installment of the Science of Sound.

If you missed Part I or II, just scroll down the page.

Remember, all sound waves are created by vibrations: this includes your own voice. When we speak (or make any other vocal noise) air passes through our vocal cords, causing vibrations. The tighter your vocal cords are, the higher the pitch of the sound they make. If we were to put a camera straight down our throat to look at our vocal cords, we'd see something like this:

Basically, when we go to breathe, our vocal cords open like the picture on the left. When you go to speak, the folds close up. When you push air through them, it creates a vibration, which in turn creates the sound of your voice. Since everyone's vocal muscles are shaped slightly differently, everyone has a unique sound to their voice.

Neat stuff, right? The folks at PowertoSing have created an excellent resource, and the video below shows you live action shots of your vocal cords in action. It also shows you how we make high pitches and low pitches, and what our vocal cords look like making those sounds. It's about five minutes, but well worth it:

When I showed this video to middle school students, half of them were always grossed out by it. Then again, I think middle school students tend to be grossed out by literally everything or nothing at all!

While we're talking about vocal cords, I wanted to talk about some common misconceptions about voice. Remember, everyone's vocal cords are unique to them. In general, females have vocal chords that produce higher pitches, and males lower. However, that's not always the case. Boys start with higher voices that lower in pitch as they mature; but some men (through practice and development of the vocal muscles) are able to keep that higher pitched voice and sing well with it. (Think Justin Timberlake, Michael Jackson, etc.)

In fact, in the Renaissance Era it used to be quite common for young boys within church choirs to be castrated so that they retained their higher pitched voices for use in the chorus. (Women were not allowed to sing at this point in history). These castrated, male singers were called "castrati" singers. Unfortunately, this practice continued well into the 1800s. Below is a link to a recording of Alessandro Moreschi, singing Ave Maria. He lived 1858-1922, and is widely considered to be the last castrato singer.

Thankfully, there are many successful male singers today who don't need such drastic measures to sing high. Since the vocal cords are muscles, they can be trained like anything else. Here is a short clip of Mitch Grassi singing with Pentatonix; he has the highest pitched voice of the singers in the group. Traditionally, male voices are grouped lowest to highest as follows: Bass, Baritone, Tenor. Mitch is a classified in a group above Tenor, known as a countertenor. The whole video is long, but you'll get the idea quickly.

Just as males can have naturally higher voices, females can have naturally lower voices. Traditionally, female voices are classes low to high as alto, mezzo-soprano, and soprano. Just like the males however, there are women who can sing lower. They are classified as contralto singers. Here is a fun video of Helen Leahey attempting to break the world record of the lowest note recorded by a female.

My point in all of this is that everyone's vocal sound is unique; you shouldn't be swayed one way or the other that you should sound a certain way. If you would like to sing higher or lower, you can train your voice to do so through patience and hard work. (Similar to how an athlete trains to run longer distances, lift more weights, etc).

If you're interested in hearing more of Pentatonix, I highly recommend them. There is a link at the top of the page you can click to check out their albums.

I went a bit longer than I wanted on that, but I had fun! We'll save my other topic for next week: Why does sound carry over water? How does sound travel in general?

Thanks for reading! If you like what you see, be sure to subscribe here and follow me on Facebook and Instagram!

-DMM

The Science of Sound, Part II

Welcome to Part II of the continuing series of the Science of Sound! If you missed the first lesson, you may want to click to go back and read so you're caught up.

I found a really neat site where you can play around with the different hertz levels, though be careful with your speaker volume if you go extremely high or extremely low. It's pretty entertaining to see how good (or not) your hearing really is. At the end of the post I'll include another link to a YouTube video that's a similar hearing test.

Today, we're going to talk about three topics:

-how hertz relate to a piano

-why do some notes sound good together, and others don't?

-what the heck is timbre?

Last time we learned all about hertz, and how they measure the pitch (highness or lowness) of a sound. Even if you don't have any experience in music, you probably at least know that each key on a piano plays a specific note (or pitch). Each note has a set hertz, since the hertz refers to how many waves per second the sound has. See below:

As you can see, each note has a set hertz. If you went and visited the hertz generator I mentioned above and here, you could actually go and recreate these tones by matching the specific hertz.

Why do some notes sound good together and some don't? When two notes don't sound good together, we call that sound dissonance. There is a scientific explanation for this. When the sound waves cross each other in a pattern at some point in their wave, it produces a sound that is pleasing to the ear. For example, let's take the two notes above of C and G, recorded on my piano.

The combination sounds good to the ear, because the pattern of the sound waves line up every so often in a pattern (for more information that is heavily mathmathical, visit here). Contrast that with the following video, which is of me playing an E and an F.

Ignoring the fact that the video ended up sideways, you should definitely hear a difference. The notes sound extremely dissonant, because the sound waves don't ever cross in any particular pattern, and so clash against each other.

When composers write music, they have to keep these dissonances in mind. In fact, sometimes the best moments in music come when a composer writes a dissonance in on purpose. Here's a an easy example by the Georgia Tech marching band, though I suggest skipping to the 1:30 mark to keep it short and sweet.

I do love the sound of a good, solid marching band. It's interesting you can have so many different instruments and sounds come together like that. Each instrument has its own flavor, or "timbre". (Pronounced "tam-ber". No falling trees here).

In the music world, timbre has nothing to do with volume or pitch. Instead, it refers to the characteristics that make each sound unique. Sometimes timbre is referred to as tone color, but scientifically it refers to the shape of the sound wave. When we think of a normal sound wave, we probably think of the smooth, curved arches we've seen so far. If instead of those arcs, the wave was shaped like a rectangle, the sound would be different.

Go here and play around with some of the different timbres; it's really pretty fascinating!

The more jagged the shape, the more harsh the sound will be. You will find that the smoothest looking sound waves produce the sounds easiest on the ears.

To review, there's a reason why we hear sounds the way we do. Some sounds are pleasing to the ear, and others aren't, depending on how the sound waves match each other. Timbre (or the shape of the sound wave) also greatly affects how we perceive a sound.

So, how good is YOUR hearing? This is fun, but starts out at a hertz only audible to dogs and works its way down. Make sure you're in a quiet environment, and watch your volume if you have headphones in. Pause the video when you hear the sound, and see how you did!

Have you ever wondered what your vocal chords look like? Why is it that sound always carries more over water? We'll dive into that next week on the Science of Sound, Part III!

-DMM

The SCIENCE of SOUND

Science and sound are irrevocably tied together (mathemathics as well, but anywho). Why does your voice sound so different when you hear it recorded versus when you normally talk? I'm not normally a math or science gal, but this stuff is fascinating.

All sound is energy that is caused by a vibration; sound waves. Sound waves that are more mathmatically perfect make sounds that are more pleasing to the ear (such as an instrument, bell tone, etc), and ones that aren't we would classify more as "noise". There is more to the mathmatics of it, but I won't go into that here.

My amazing, fantastic MSPaint skills aside, above is a rudimentary representation of "music" versus "noise". The first group of sound waves would be something considered noisy; a jackhammer, a loud truck, etc. The waves are inconsistent and are not symmetrical at all. The bottom group of waves would be a sustained tone of an instrument or a human voice, or even an electronic sound. You can see these waves are much more uniform (disregarding the aforementioned MSPaint skills).

When those sound waves (vibrations) are heard by us, it becomes sound. Or does it? It goes back to the saying of "If a tree falls in the woods, and no one is around to hear it, does it make a sound?" Many people would argue something isn't a sound unless it's heard by someone or something. I'll let you toil under that philosophical question.

When we hear vibrations, whether or not something sounds high or low is measured by the sound wave's hertz. Here is a quick chart to give you an idea:

Humans can generally hear anything starting at 20 Hertz (or hz) and going as high as 20,000. Someone with better than average hearing could hear more. The frequency or hertz of sound refers to its pitch; or how high or low it sounds. The lower the hz, the lower the sound. Think of a dog whistle; the frequency of the dog whistle is so high human ears can't hear it, but dogs can!

Volume is separate, and measured in decibels. Most of us know that if we listen to a sound at too high of a decibel level, we can cause hearing damage.

So to review, how loud something is refers to its decibel. If we want to translate that into its sound wave, we look at volume as amplitude. How high or low pitched something sounds is measured by hertz. When looking at a sound wave, we refer to that as its frequency.

Phew, that was a lot of information! Now onto something I had always wondered:

Why does my voice sound so different when I hear a recording, versus when I hear myself speaking?

I've always wondered this! The answer is just as scientific as everything above. The folks at SciShow have made a great video about this.

Well, that does it for Part I of the Science of Sound! Stay tuned for Part II!

-DMM