Sometimes the problem may be that the child has difficulty discriminating between sounds and that difficulty needs to be addressed first. Some children cannot perceive if two sounds are the same or different and need a lot of guided practice to learn to do this. Here are a couple of suggestions. Go to the website:
http://www2.cambridge.org/interchangearcade/sortbytype.do?level=0&type=Cup_word_up. On this site a child practices discriminating between two words or phrases, for example “thirty/thirteen” and “a brown coat/a green coat”.
The second website I recommend is: http://brainconnection.positscience.com/brain-teasers/. Have your child play the following games.
Sound Dominoes -- "Sound Dominoes is a phoneme matching game that builds short term memory and sound and word recognition ability."
Memory -- "In the memory game, listen carefully and find the animal sounds. Click on the window to make the animal appear and hear its sound. Click on the other windows to find its match."
I copied the descriptions above directly from the website. Other games that the site has that work on sound discrimination are: Platyhop, Acorn Drop, Frog Jump, and Monkey Juggle.
The above activities can be introduced without resistance from the child since they are in a fun game format.