First Layer Kohonen Nets

49 node first-layer net trained on 500+ extracted units
allowed to shift by +/-10 time bins and by +/- 1 frequency bin:

Below is a net which wraps around at the sides (i.e. it is toroidal).
Units allowed to shift by +/-10 time bins and by +/- 2 frequency bins:

An interesting quirk. The following net was produced by an attempt to
wrap the net round. There was a mistake in my code, and it's actually
a 'winner takes all' net (i.e. no neighbourhood, each node is
isolated).

As you can see, most of the nodes have been left random and only 19
prototype units have been produced by the net:

Below is a deliberate winner-takes-all net with 10 nodes.
Units allowed to shift by +/-10 time bins and by +/- 2 frequency bins: