This is actually question my daughter posed and I’m pretty stumped. She asked how, if two people with (let’s say) perfect pitch sing a song, how is it possible that we can still tell who is singing when the notes would be identical?
Note: I know absolutely nothing about music, but figured this was the best place to ask for her.
Edit: Wow, many of these answers are incredible! I had no idea this would receive such in depth and thoughtful feedback. I have learned a huge amount. I was not exaggerating above when I said I know nothing about music (I don’t even know what pitch is – just quoted my daughter on that) and I’m grateful to those of you who took the time to help me learn.
In: Biology
Timbre is the key thing here along with the overarching concept of tone. It’s also why any two different instruments (a violin and a saxophone, for example) can play the same note at the same pitch and be easily distinguishable.
The architectural and performance variables of the instrument play an intrinsic part in the “sound”. A saxophone — being made of metal, having a reed, and requiring air flow and key fingering — will undoubtedly create different tones than a violin — being made of wood, having strings, and requiring vibration via bow and manual input on the finger board.
Something nobody else has really touched on in depth: Waveforms.
So in really basic electronic music, you’ve got sine waves, sawtooth waves, and square waves. Every note is literally just a pulse of air at a given frequency. It’s why car engines, which are literally just exploding aerosolized gasoline, make audible notes.
There are videos you can search (I’d link one but I can’t right now) that show the relationship between frequency and pitch.
**So what does that have to do with a sine wave?**
Well the waveform is what the sound wave actually looks like. A square wave is completely no noise, then immediately completely 100% energy, then back to complete silence. A sawtooth wave is like a square wave at first, but instead of staying at 100% energy it trails to zero over time. A sine wave is just a very rounded (sinusoidal) square wave so the energy changes are smoother.
And all of those waves have different timbres, or tones.
But if we layer a sawtooth wave with a sine wave, or we decide to cut a huge divot in the top of a sine wave, you’ll get different tones still. Playing with these waveforms is precisely how electric keyboards attempt to synthesize other instruments.
Okay so now we can step away from the electronic sounds, and go back to the natural world. Horns, car exhausts, and the human throat all have characteristics that make their own wave form. There are so many things that can affect which frequencies are highlighted and which frequencies are subdued. You can choose to manipulate those with tongue placement and mouth shape, or bell shape and pipe length or construction material.
A voice is an instrument. While some sound similar (some even sound almost identical), subtle differences like size, materials, shape, make them sound different. Those are odd terms to use when describing people, but a 110 lb woman is going to sound different than a 300 lb woman singing the same note. The shape of their mouth, the way they push the air out, all make a difference.
It’s like if I have a trumpet and a flute play the exact same melody. They’re both wind instruments, but they sound different enough that you can differentiate them.
One of the components of a musical note is its *timbre* (pronounced TAM-bur). Timbre is all the sounds associated with the source that *aren’t* part of the pure tone.
Instruments (and the human voice – hereafter I’ll just say instrument, but it works the same either way) don’t produce a pure tone. The instrument creates the root frequency, the pitch you’re trying to make, and also overtones. Take a guitar string: it will vibrate at a particular frequency, and it will also vibrate at exactly twice that, and exactly thrice, and exactly four times, and etc. The shape of the instrument and what it’s made of and the size and shape and material of the main source of vibrations (lips, reeds, vocal cords, etc.) all change which overtones get amplified and which get diminished. Your ears can hear the differences in these overtones, although your brain filters it from your conscious perception of the sound unless you focus on it.
With a human voice, this includes the size and shape of your mouth and lungs and sinuses and skull and thickness of your skull and jaw and tongue and so on and so forth. All of these things change the overtones in subtle ways, so that even when the root pitch is the same the pitches around it won’t be.
Timbre also includes all the unique sounds that come from the instrument: things like key clicks or valve movements or breath noises or little scratchy bits in your voice, etc.
Edit: “That’s not how you pronounce ‘timbre!'”
[It is in American English.](https://en.m.wiktionary.org/wiki/timbre) It is at the very least *one* correct pronunciation in English. Yes, I know it’s borrowed from French but this comment isn’t in French, it’s in English. I don’t expect everyone on the internet to understand English, but if you’re reading this in the original that means you understand English. Some 60% of the English lexicon comes directly from French so if you’re gonna get upset every time someone pronounces a French word “wrong” in English you’re not going to get very far.
The sound isn’t just the exact pure tone of the pitch they’re singing in. Every instrument and voice has a distribution of frequencies around the main pitch, known as its *timbre*. A piano, for example, is very concentrated around a specific pitch, while a drum is more spread out (which makes piano a better instrument for expressing detailed harmonies, but also makes it sound much more dissonant if you play a note that’s a bit off).
Every response I’ve seen is correct, but I’m a music teacher and here’s a great way to visualize it.
Sound comes in the form of waves, and waves are fundamentally the same whether they’re waves on the water or in the air. If you took two waves of water and compared them for visually-identifiable differences, after enough thought you might realize that there’s a few things that can be measured:
1. Height
2. Width
3. “Texture”
Height simply means measuring from a trough to the peak of the wave. Width is measuring from trough to trough (or from peak to peak). The third one is SLIGHTLY more complicated but it would be, for example, the difference between a glassy smooth wave, or a choppy one. It’s disturbances on the surface of the wave and there are millions of slight variations that are possible there. You can have two choppy waves, but their choppiness can be varied.
If you can see those three characteristics in water waves, you can also HEAR them with sound waves! It’s just harder to imagine because we find it easier to think through our eyes.
When you hear a taller sound wave, you perceive that as volume. Taller waves are louder, shorter waves are quieter.
When you hear the width of the waves, you perceive that as pitch. Narrower waves, bunched up closer together are higher in pitch. Broad waves are lower.
That leaves the texture. If you can see it, you can hear it… but it’s an easy one to forget about. If you have two sounds that are at the same pitch and volume, and yet sound distinct… that’s the texture! In music we call it the timbre but it’s the same thing. A choppy wave sounds much different than a smooth one, even if they’re the same height and width.
Examples of textures you can observe:
1. Someone with a really nasal voice, or a deep booming voice.
2. On a piano, the thick gravelly sound of the bottom notes, compared to the clear bell-like sound of the high notes.
3. The pluck of a guitar vs. the pluck of a harp.
4. Every vowel is technically a different timbre too! If you sing every vowel on one pitch, the fact that you can discern the difference between an “a” and an “e” means that they have different timbres!
Interestingly, it’s the beginning and end of notes that hold most of the key in differentiating between instruments. The middle sounds pretty similar: https://youtu.be/thD6TNUoyIk
You might also get good answers at /r/musictheory
Music teacher here.
The same way that you can have dark green and light green and green stripes and green spots and shiny green and matte green (importantly, all without changing the color towards red or blue), you can have a note come out in many different ways without changing the pitch (high-ness or low-ness of a note).
In music, this is called timbre (pronounced TAM-BER for some reason), or “Tone Color”.
As an interesting exercise, have them hit a single note, and move their mouth through the vowels.
Compare the ‘O’ sound with the “EEEE” sound. The O sounds lower, while the EEEE sounds higher, even though the pitch stays the same.
When we make sounds with our mouths, there is one main pitch, and lots of little “sub-pitches” called harmonics, that change the way the main pitch sounds.
There exists a type of note with no extra harmonics, called a Sine Wave, which is only the main pitch and nothing else. YouTube can play it for you.
A piano, guitar, marimba, glockenspiel, flute, harpsichord, harp, and…you get my point, can all play for the most part a set of identical notes, and yet you could easily distinguish them from one another.
Human voices are all different in the same way. We all have differences in our voices that contribute to how our singing voice sounds. Though I will say, the more well trained they are and how perfect their pitch is, you’d find it hard to distinguish 2 female soprano singers singing an E6 or similarly high note. But down in the mid range of your singing voice which comes from a combination of your chest and head voices, you’ll start to hear the differences between 2 singers quite clearly.
A fun example—
If you take recordings of instruments playing the same sound, and you cut off the beginning and end for each instrument, you’ll have trouble identifying the difference.
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