Did you pair the headset with the iPod?
Bluetooth devices
You can use iPod touch with the Apple Wireless Keyboard and other Bluetooth devices, such as Bluetooth stereo headphones. For supported Bluetooth profiles, go to support.apple.com/kb/HT3647.
Pairing a Bluetooth device with iPod touch
WARNING: For important information about avoiding hearing loss and about driving safely, see the Important Product Information Guide at www.apple.com/support/manuals/ipodtouch.
Before you can use a Bluetooth device with iPod touch, you must first pair them.
Pair a Bluetooth headset, car kit, or other device with iPod touch:
1 Follow the instructions that came with the device to make it discoverable or to set it to search for other Bluetooth devices.
2 Go to Settings > General > Bluetooth and turn Bluetooth on.
3 Choose the device on iPod touch, and enter its passkey or PIN number. See the instructions about the passkey or PIN that came with the device.
After you pair headphones with iPod touch, the product name and appear on the screen when you are viewing audio or video playback controls. Tap to switch to a different audio output, such as the internal speaker.