Different makes and models of TV sets have different 'sensitivities'. That's their ability to 'pull in' weak signals. A freezing picture is a classic symptom of insufficient signal strength, so it seems extremely likely that your aerial can't provide a strong enough signal for your new set. (If your previous set worked without any problems, it simply means that it had a better 'sensitivity' than your new one does). You need to upgrade your aerial system (which, unless you've got fairly new cabling already, means replacing both the aerial and the cable).
I'm uncertain as to the cause of the sound problem but it might also be related to yor TV being unable to probably resolve the audio signal due to insufficient signal strength. You won't be able to tell for certain until you've sorted out the aerial problem.
Chris:
PS: It might be worth while trying the addition of a cheap signal booster (if you're not already using one) before replacing the aerial. If the signal is only marginally below the required strength it might possibly do the job.