Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Sound quality

  1. Nov 30, 2015 #1
    It's a very simple question but still,
    When two identical guitars are played day two persons to give notes of the same pitch, will they differ in quality?
    Please specify with reason.
    Thanks for the replies.
     
  2. jcsd
  3. Nov 30, 2015 #2

    f95toli

    User Avatar
    Science Advisor
    Gold Member

    Sure this will differ. The pitch just tells you which note is played; there are lots of other variables that affect how we perceive the sound (relative amplitude of harmonics, amplitude, duration, envelope etc).
    Hence, if by "quality" you mean the spectra as a function of time (i.e. a spectrogram) then the answer is yes.

    As an extreme example just compare the sound of an open and palm-muted string, the pitch is the same but they sound very different.

    Note that the same is true for all analogue instruments, you can change the sound of a e.g. piano quite a bit depending on how you play it.
     
  4. Nov 30, 2015 #3

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member

    Any musical instrument is a very complex structure. So are instrumentalists. They will pluck the strings at different distances from the bridge (altering the harmonic content) and with different force and velocity. The stopping finger can be pressing hard or sofltly and the finger pads can greatly affect the damping (just try an experiment where you stop hard or soft / right behind the fret wire or well behind it. If a barre is being played, the strength of the hands can make a big difference to the damping of the string. Then the tension can be altered by the stopping finger (not only when pulling the note) and can brighten a note by raising the pitch fractionally. I have noticed that the dynamics of the stopping finger can make a difference to the sustain; it's easy to kill a note by removing the finger too soon, ready for the next note. Many jazz guitarists seem to release between notes (that's part of the 'jazz sound'), even when there is no chord change whereas others get more continuous sounds by keeping the pressure. The action makes a difference to what you can actually achieve, here. A high action can be very hard work, which some players can cope with and others not. They many never fully depress the string. In an acoustic guitar, the arms and body can damp differently, depending on how the guitar is held or the clothing.
    I am sure there will be other factors that I haven't thought of. But, strangely (?) a good player always seems to make a nicer sound than a beginner- and certainly better than I can.
     
  5. Nov 30, 2015 #4
    By saying quality I meant timbre.
    And if amplitude and frequency is same does that mean timbre will be same if the sound is played on identical instruments?
     
  6. Nov 30, 2015 #5

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member

    My last post gives a list of reasons why notes may not sound the same from player to player. i.e. Timbre will be different - and even pitch, in subtle ways. The player can make at least as much difference as you get between instruments of the same quality / price group. Of course, a really duffer guitar will probably never sound nice but a £1000 instrument can be made to sound terrible by some people.
     
  7. Nov 30, 2015 #6
    OK, one last time
    What if the same person plays the same notes on both these instruments (without any human error) will they differ.
    I mean is there any property other than pitch and amplitude due to which quality (timber) of sound will be different.
     
  8. Nov 30, 2015 #7

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member

    Yes, absolutely. A single pure tone (sinusoid) is the only note that will sound the same as another of the same pitch. All instruments have harmonics and also the attack and decay / sustain will affect the sound. Pitch and amplitude are easy quantities to measure and describe but the detailed shape of the waveform is pretty well impossible to quantify - except in very broad terms. Reading reviews of instruments (as with hi fi and radio reviews) is full of BS phrases and the occasional meaningful one where the writer has tried to describe the sound. If you google terms like stringed instrument waveforms then you will find images and soundbytes. You have used the term "timbre" and that is used to cover all that stuff, plus all the other expressions like "bright", "toppy", "dead", "groovy", which are only qualitatitve and mean different things to different people. Perhaps my reply could be summed up by "Yes but you can't measure it reliably"
    Cheers.
     
  9. Dec 1, 2015 #8
    It is very importantwhat materialthe stringswere made
     
  10. Dec 1, 2015 #9

    I said already the guitars were identical so the material of the strings would also be same.
     
  11. Dec 1, 2015 #10

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member

    If everything is identical then why should they? You are changing the rules here.
    Different people will make different sounds on the same guitar and one person will make different sounds on two identical guitars.
    I am not sure where you are wanting to go with this any more - except to establish that 'timbre' is something extra, on top of pitch and amplitude.
     
  12. Dec 2, 2015 #11

    OK let's forget about any guitars.
    If there are two sounds with same frequency and same pitch and everything else is also same then their timbre also has to be same if they are being produced from identical sources or same source.
    Or else every single sound produced in this universe is unique.
     
  13. Dec 2, 2015 #12

    sophiecentaur

    User Avatar
    Science Advisor
    Gold Member

    "Identical" means identical but two real sounds will differ by a finite amount. That's the same for all quantities, applied to all things.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Sound quality
  1. Sound refraction? (Replies: 16)

  2. What is sound? (Replies: 31)

  3. Sound and heat (Replies: 1)

  4. Speed of sound (Replies: 2)

Loading...