Professional musicians prefer strobe tuners for their tuning speed and accuracy. The HotPaw inTuna Strobe Guitar Tuner allows you to quickly and accurately tune your guitar via unique, responsive, and high contrast visual displays. Also included is a multi-stobe tuning mode, simultaneously displaying a strobe for each string... fast and usable even in noisy environments.
inTuna includes both a large frequency meter and a precise pitch strobe window. You can let inTuna auto-select the guitar string being tuned, or touch the Lock icon to lock tuning to a selected string. A 6 string tuning indicator indicates the string which has been selected for pitch measurement. Above the tuning indicator is a unique waterfall waveform display within a Strobe window to assist with Extremely Accurate fine tuning. Configuration options include support for 8 popular guitar tunings and a Concert-A440 frequency adjustment. The iPhone's microphone is used for sound input, or you can plug a headset or mic into the headset jack.
Also, please take a look in the App store at HotPaw Sing-inTuna, a "vocal tuner" application, and Music Spectrograph for music visualization and as an aid for music transcription.