Click on the buttons to play the sound like a telephone dialing. Press the right-bottom gray button to stop the sound (or key "/") 1/2/3/6/9/#/C somehow sounds like a D major scale which can be used to play a song. Keyboard Support: 7 8 9 a <space> 4 5 6 b <up arrow> 1 2 3 c <down arrow> */<left arrow> 0 #/./<right arrow> d
The only sound file used is the A440 sine wave, using pitch effect to adjust the frequency. The first four columns are 1209 Hz, 1336 Hz, 1477 Hz and 1633 Hz while the first four rows are 697 Hz, 770 Hz, 852 Hz, 941 Hz and the three special tones use consecutive frequencies from 350 Hz, 440 Hz, 480 Hz and 620 Hz 350 Hz: 3.962 semitones below A440, sounds very close to F (-4) 440 Hz: defined as concert A 480 Hz: 1.506 semitones above A440, sounds close to B♭ (+1) and B (+2) 620 Hz: 5.937 semitones above A440, sounds close to E♭ (+6) 697 Hz: 7.964 semitones above A440, sounds very close to F (+8) 770 Hz: 9.688 semitones above A440, sounds close to F♯(+9) and G (+10) 852 Hz: 11.440 semitones above A440, sounds close to A♭ (+11) and A (+12) while close to 1 whole tone above 770 Hz 941 Hz: 13.160 semitones above A440, sounds close to B♭ (+13) 1209 Hz: 17.499 semitones above A440, sounds close to D (+17) and E♭ (+18) 1336 Hz: 19.228 semitones above A440, sounds close to E (+19) 1477 Hz: 20.965 semitones above A440, sounds close to F♯ (+21) 1633 Hz: 22.703 semitones above A440, sounds close to G♯ (+23) https://en.wikipedia.org/wiki/Dual-tone_multi-frequency_signaling keywords: phone sound telephone mobile
