Simple Tuner example - frequency not accurate about 1000 Hz?

Is there any way to improve accuracy of the frequency detection, above 1 KHz? When I try the Simple Tuner example it seems accurate up to 1K-2K, but beyond that I get messed up readings ?

eg. if I play an 8K sine wave at the tuner, it only reports it as 4K ? 4K seems to be the max value I can attain ?

I tested on a pair of iPhone 4s

Simple Tuner example is here:
http://developer.anscamobile.com/node/4359/subscribe#subscribe

Can I improve the accuracy and how? I know some may think ,well…so what ? But it’s really important for something I’m working on. [import]uid: 97524 topic_id: 18567 reply_id: 318567[/import]