UA-160819121-1

Sound- 


Moles do have ears but unlike many creatures, these have no Pinna. This is the part of the ear that sticks out like on the side of our heads and with its shape funnels the sounds into the ear. Without  the Pinna sound waves would not be directed into our auditory canal and would make it harder to understand or the sounds could be lost. When we need to hear sounds better we cup a hand around the Pinna, like what the character on the right is doing here.
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.
Sounds travel along tunnels and tubes, this form of communication was once used on ships to very good effect to communicate between the bridge and the engine room. You can try this for yourself, get a length of tube and ask a friend to speak into one end, place an ear at the other end to listen to what they say. You are now hearing the same way that a mole does. Sound actually travels faster and more efficiently in the ground then in the air, this is because the molecules and atoms are closer together allow the vibration or sound wave to pass from one atom to another better. The speed of sound in the air is 350m/s in the ground this increases to an amazing 5000m/s. I have recorded sound from inside a moles tunnel , using special microphones that record low frequency. The world around them is completely auditory to them. Every sound is audible, voices, bangs and especially aircraft and cars, they can hear and experience everything that is happening above them.  


The moles ears are hidden beneath the fur and are a small hole, a short distance further back from the eye.
The sound will enter the hole and travel into and along the auditory canal, this is a tube of bone that directs the sounds to the eardrum [tympanic membrane], as any sound waves pass from the tunnels into the smaller auditory canal they are amplified, so the mole will hear the sounds clearly.

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.

This recording is a mole digging a tunnel, it was recorded with a microphone buried in the moles tunnels 3 meters away from the point the mole was digging. You can now experience what a mole hears. As well as recording the mole working we can also let you hear the ambient sounds of everyday life that the moles experience, these sounds are again from a microphone set in the mole tunnel and covered over with soil..

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.