The moles do not need a Pinna and for very good reason, a large funnel on the side of the head would be in the way of the moles need to twist and turn in the tunnels and funnelling sounds into the ear is not required as the mole tunnels themselves direct sounds along them.
The special microphones I use to record the environment of the moles in their tunnels are only capable of recording sounds at 20 Hz which is the same level as a human whisper. We know moles can detect sound waves to an even lower frequency of just 5 Hz using special stiff whisker like hairs on their body. I am not sure if we can record sound frequency to this level below the ground, but using a special microphone used for recording the low frequency sounds made by bats that can record as low as 5 Hz I have been listening to the world of moles in a new dimension.
The recording of sounds at 20Hz have opened a whole new concept to the moles perception of our world. They can hear everything we can, using a microphone placed in the moles tunnels I have recorded the everyday sounds at many locations, including gardens and farmland. The microphones are set in a plastic tube to replicate the auditory tube of the moles ear, this was positioned pointing downwards and the microphone set level with the tunnel roof. The whole microphone was then completely buried.
These samples are amazing as the beginning of the track you can hear the flight of a bee flying around a plant close by the position of the microphone, it pauses to gather nectar and then flies around again, the microphone was only 100mm deep to record the bee. In the next track the microphone was set deeper 200mm a wood pigeon can be heard in a nearby tree and then the flight of an aeroplane which the sound of the engines penetrates deep into the ground. The mole can certainly absorb the auditory world through both sound waves and vibrations.