Title. Don’t they have the same frequency? Why would they sound different?
In: Physics
Really good question, the answer is called “Timbre” to summarize from wikipedia –
In simple terms, timbre is what makes a particular musical instrument or human voice have a different sound from another, even when they play or sing the same note. For instance, it is the difference in sound between a guitar and a piano playing the same note at the same volume. Both instruments can sound equally tuned in relation to each other as they play the same note, and while playing at the same amplitude level each instrument will still sound distinctively with its own unique tone color.
In the physical world the difference is caused by slight variations in the wavelengths of different sounds even when playing same frequencies
The actual *note* as we know it may be the same, but the underlying harmonics are not.
Let’s take an overdrive-riding djent guitarist managing to hit the same note as their bassist. Let’s toss some arbitrary Hz number out there like 200hz frequency for the note. The actual sound may be passing through the zero point 400 times a second, but the actual shape of the wave would not be purely sinusoidal. For example the guitar since it is overdriven is probably clipping, so instead of nice smooth peaks and valleys the wave reaches a high point and sharply levels out before dropping down. Meanwhile the bass guitar soundwave might look a lot more like a natural sine wave.
So in effect a note is just how many times per second the soundwave “passes through zero” (how fast it is vibrating), but the actual shape of that soundwave gives it the distinct actual sound. You can play around with this for yourself with a free app from the app store on your phone that gives you instruments like sawtooth waves and square waves — the actual shape of the wave is different.
A sound isn’t usually just a single frequency, it’s actually collection of frequencies called [harmonics](https://en.wikipedia.org/wiki/Harmonic_series_(music)), which are all a multiple of the fundamental frequency. Different instruments have different harmonics.
No they are not always the exact some frequency, Notes come in sets of octaves. for example, the note A has a frequency of 440hz, if you move it up an octave, making it a higher pitch, it is 880hz, down an octave is 220hz.
Different instruments play generally in different octaves. Take a cello and violin, they can play the same note, but the much larger cello is going to play it in a much lower octave with a much deeper sound.
Sounds also sound different to their length. A flute the is putting out a bunch of quick bursts of notes is going to sound different than a violin playing the note by pulling the bow long across the string.
The note you hear is the fundamental frequency of the sound wave. This is the main way that instrument causes vibrations. But there are many ways for a string, drum membrane, or tube of air to vibrate.
Since instruments use different materials and are crafted differently, each and every instrument will activate these other vibrations – called harmonics – at different levels of intensity. Musicians refer to this expression of harmonics as timbre, while physicists refer to them as the sound’s frequency spectrum.
I suggest you download a FFT Spectrum Analyzer app on your phone and repeatedly play a single note for it. Perhaps try whistling loudly. You’ll notice a VERY large peak (the fundamental frequency) and a bunch of tinier peaks (the harmonics).
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