iPhone app that records audio during specific time
try this free app 

Some of the features:Compare These Features:


One Touch Recording
One Touch Stop &amp; File Saved
Super Small MP4 Recording File Sizes
Send Voice Emails Up to 5MB
Records for Seconds or Hours
Pause Record and Resume
Adjustable Recording Qualities
Flip Mode For Mic on Top Recording
Record Timer and Playback Counter
Double Tap for Quick Playbacks
Auto File Naming w/Optional Renaming
Finger Scroll Through Messages
Pause Play and Resume Modes
Drag Slider for Seek/RWND/FFWD
Audio Level VU Meter
Displays File Sizes and Time Stamps
Plays Thru Earpiece, Speaker, Ear Buds
Use Devices' Built-In or Add-On Mics
Ringtone Recording Feature
EZ Sync Recordings to Computer
Great Visual Voicemail Like Interface 
Voice Reminder Notes
Send Voice Notes Through Apple's iMessages