How many Echo Meter Touch recordings can my iOS device hold?
The number of recordings are dependent on the available storage on your iOS device. The storage capacities on compatible devices range from 16 GB to 256 GB. The operating system and your other apps take up room, but even at the smallest size, there should be plenty of room for several nights of monitoring. Figuring a few megabytes per recording sampled at 256 kHz and a few hundred recordings a night, that's about half a gigabyte per night.
If you are using the Echo Meter Touch 2 Pro, note that recordings made at a sample rate of 384 kHz take up 50% more space than those recorded at 256 kHz.