Wifi channel selection
Many wifi access points look for the quietest band, and start on that.  Your computer when it isn't connected essentialy listens on 1, then 2, then 3, then 4... 
It creates a list of all the ones it finds, then presents the list to you.

Some WAP's also can be configured to set a particular channel.  In addition you may be able to change the default power setting.

My experience has been that WAP location and antenna orientation have far more to do with SNR than channel number.  If this is a home network, you may want to look at putting a WAP at opposite ends of your house.  If you do this, only ONE of them serves DHCP requests.  Or both serve to a central computer.  Or you set all local addresses manually.  2 DHCP servers is a pile of grief.

To formally answer your question:  At the client end, no it is not possible.  At the WAP yes it is possible.  

Hope this helps.