I have a Yamaha baby grand that needed a full tuning every 4 months, so every time I had to pay $90-100 to have a professional tuner tuning my piano (so spending a minimum of $300 a year). After one year, I got sick (too much money!), so I bought a good piano lever, miscellaneous material to tune the piano and tried this little program. Well, I am a professional violinist so my hear is very good to understand if a note is high or low, but sometimes I get confused and this little program helps me to understand right that.

Now I am keeping my piano tuned by adjusting those single notes every two weeks and it's great.

Be careful though! To tune a piano is not so easy and immediate, you must be a good musician first (to know the 5th basic tuning), have a good hear and be careful to turn your string pins VERY slowly.