Matt had an interesting idea of using your phone to tune your guitar. So, I decided to do a little investigation of how that would actually work.
A touch tone phone produces two frequencies for every button. Here’s a chart:
| 1209 Hz | 1336 Hz | 1477 Hz | |
| 697Hz | 1 |
ABC 2 |
DEF 3 |
| 770Hz | GHI 4 |
JKL 5 |
MNO 6 |
| 852Hz | PRS 7 |
TUV 8 |
WXY 9 |
| 941Hz | * | OPER 0 |
# |
Next would be to find a note that is close to one of these frequencies. So I consulted a frequency chart.
The closest that I could find are:
| 1479.98Hz – F# | 1477Hz – Buttons 3,6,9,# |
| 698.46Hz – F | 697Hz – Buttons 1,2,3 |
However, you can’t play F or F# on an open string. So, it’s going to require a lot of effort to press the “1” button on the phone, play F on the guitar, turn the peg, then repeat. There is also additional error since the phone frequencies are within a ±1.5% tolerance.
So, if you happen to need to tune your guitar and you’re stuck without a tuner or a tuning fork, and you happen to be near a phone, it’s possible to tune your guitar that’s close enough for government work.
Note: I haven’t actually tried this with a guitar, so if you try this out, let me know how it works for you.
Links:
DTMF
Touchtone
DTMF Reference
Scales
Cyberfret
Frequencies of musical notes