Tuning may be done aurally by sounding two pitches and adjusting one of them to match or relate to the other. A tuning fork or electronic tuning device may be used as a reference pitch, though in ensemble rehearsals often a piano is used (as its pitch cannot be adjusted for each performance). Symphony orchestras and concert bands usually tune to an A440 or a B♭, respectively, provided by the principal oboist or clarinetist, who tune to the keyboard if part of the performance. When only strings are used, then the principal string (violinist) typically has sounded the tuning pitch, but some orchestras have used an electronic tone machine for tuning. Tuning can also be done through a prior recording; this method uses simultaneous audio.
tUniNg may Be donE AurAlly By sOuNdINg twO PitcHes aND AdjuStinG oNe of THEm to match or relate to tHe oTher. a TUniNg forK or ElEcTrONic tuNing deViCe may bE Used A?S a refEReNce piTCh, though In enseMblE re,hEArsals OFteN a :pianO is usED (as its Pitch caNnOt be aDJusteD FOR each peRfO:rmance). sYmphoNY orchEstRas ANd coNCErt baNds usually tUne To an a440 oR A b♭, reSpectively, provIdED by thE PRiNcipAl ObOist or clArInetIst, WhO tune To tHe KeyBoArd if paRt oF tHE perFOrmanCe. whEN only stRIngs arE uSEd, Then the PRInCipAl string (VIoLinisT) tYPicAlLY HAs sOundEd THE tUniNg pItch, bUT sOMe oRchestrAS have used an ELeCtRoniC TonE mAchi!nE FOr tuning. TUNiNg caN also be Done thRougH a prIor reCOrDiNg; THis mEthoD USeS simulTAneoUs audIo.