Pitch is a word that gets thrown around quite a bit. Some people have high pitched voices and some people have low pitched voices. Have you ever thought about what pitch means though? Sure, we know when someone’s voice sounds high pitched, but what is the reason for that high pitch? You can probably sort the people in your life into “those that have high pitched voices” and “those that have low pitched voices”. This sorting that you are doing in your head may not correspond to typical concepts of gender either. I would wager that you can think of some female friends that have low pitched voices and some male friends that have high pitched voices. There may be another pattern that you notice in these people though. I bet that most of the people in your life with low pitched are taller on average and those with high pitched voices are typically shorter. It turns out there are many factors we can look at that correlate with vocal pitch.
But really, what exactly is pitch? Like I said, we have this idea of what pitch is from just listening to something, but what actually makes something high pitch? Well, those of you with musical training are likely already a few steps ahead of me on this one. The pitch of one’s speech, similar to a musical note, is measured in Hertz (Hz) and corresponds to how ‘quickly’ something is vibrating. But what is doing the vibrating? In speech, it is our vocal folds that are vibrating when we produce vowels and voiced consonant sounds.
I have talked about the vocal folds before, but I will do a quick refresher here. Your vocal folds are the folds of tissue located in your throat that are responsible for phonation. During the production of a vowel or a voiced consonant, these vocal folds will press together and the air that passes through them at this time will cause them to vibrate producing the sounds that we hear.
Let’s compare these vocal folds to the string of a guitar. In a standard tuning of a six-string guitar, the sixth string will be tuned to E with a frequency of 82.407 Hz. What this means is that when you pluck this string, it will vibrate in a cyclical fashion and should repeat that cycle of vibration approximately 82 times every second. If you were to adjust the tuning peg and tighten the string, the note that you hear would increase in pitch and the frequency of the note would also increase meaning that the string vibrates more times per second. Conversely, if you loosen the string, the note sounds lower and the frequency of the note would also decrease.
Our vocal folds function the same way as a guitar string. The tighter you hold them together and the faster they vibrate, the higher the pitch that you produce. This is how we are able to produce different pitches in our voices as we sing and speak. But wait, I also mentioned that there was a likely correlation of the pitch of one’s voice and their height, right? Let’s go back to the guitar for a second.
Again, in standard tuning, the sixth string is tuned to E (82.407 Hz). If you place your finger on the fifth fret of the guitar and pluck the string, the note that will come out will be an A with a frequency of 110 Hz. All you are doing by placing your finger on this fret is making the string shorter by a set length to raise the pitch, so from this we can infer that in addition to tension, the length of the string also plays a factor in the pitch.
When it comes to vocal folds, it stands to reason that people who are taller also have larger proportions in most area’s of their body. I mean, you know what they say about people with big feet right… That’s right! They do say that they have longer vocal folds! Now this is not true of every tall person in the world (there are exceptions to almost everything).
Alright so now that we have a better understand of how we quantify someone’s pitch, how can we measure it? Well, thanks to modern technology, we can have software do it for us. A piece of software widely used in the world of linguistics called Praat is used to analyze many aspects of recorded speech including pitch. In the image below, you can see a spectrogram of a recording of me saying the word “fantastic”. On this spectrogram (the bottom half of the image), the blue line represents the pitch tracking that the computer calculates and the average for my pitch ends up being approximately 131 Hz (which is slightly above average for a man my age).
You will also see that there are gaps in the blue line and there is an explanation for them. Pitch can only be tracked and calculated on voiced consonants and vowels, but many of the consonants in “fantastic” are voiceless meaning that the glottis is spread open when they are produced, and the vocal folds are not vibrating. So, we know that the computer can tell us this number, but how is this number calculated? Let’s zoom in close on one of the vowels in this recording to get a better idea of what is going on.
If you look at the waveform here (in the top half of the image), you can see that even though there is a lot of variation in the line, there are patterns that are repeating in it. I have highlighted one of these chunks and you can see that it takes approximately 0.00713 seconds for one of these cycles. To convert this into pitch, we need to figure out how many of these repetitions can happen in one second (that’s what Hz stands for after all!). So if we do some cross multiplication and division like we are in high school, it turns out that this works out to 140.25 Hz, which is very close to what the computer is calculating for this particular vowel (140.4 Hz). Keep in mind that the computer is looking at the entirety of the word while we are just doing the math based on a single cycle. The computer has a complex algorithm that it uses which takes into account several cycles and the surrounding environment, but this is just a quick showcase of how it works.
And before I go on for an eternity, I think we can stop here and call this a solid primer to the mechanics of pitch. I hope that it was informative though and I have enjoyed getting back into the habit of writing like this again. I still have so much to share and I hope that you will come back to learn more. If you have any topics that you want to know more about, please reach out and I will do my best to write about them. In the meantime, remember to speak up and give linguists more data.
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Thanks. Super interesting.
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