As an "old" time ci user I can share my experience of identifying sounds as of this morning 20th September 2011!
On putting on my implant I became aware of an odd "gargling" sound that did not sound like water draining away down the faucet! More like a grating sound as if someone was gasping for air!
On further investigation I found that what had made the noise was my flat mates lawn mowers being moved into the hallway and it was the sound of the roller hitting concrete!
This goes to show that even after 12 years of experienced CI use the journey of exploring and identifying sounds continues!!
