Terrible sound, sounds like speaker blown. Got it 2 days ago.
If this is a "new to you" TV, keep reading. If it is a brand new TV, I'd be on the phone to the store to have a replacement ready for delivery / pick up. You do not want to be repairing a TV that is 2 days old.
The first thing to do is determine if the distortion is coming from the speaker or if it is on the signal going into the speaker. Do both speakers sound distorted or only one?
You didn't include the model number of your TV, so I can't speak to specifics. Look for a terminal on the rear of the set identified as "speaker" or "external speaker". If provided, there will be one set of terminals marked for the left and one for the right external speaker.
Connect a speaker directly to the terminals marked for either the left or right speaker (connect to the one that sounds distorted if only one of the built in speakers works correctly - other wise pick either speaker terminal pair.). Speakers that have RCA plugs on them, have built in amplifiers, require batteries or or to be plugged in to an outlet should not be connected here.
Alternatively, you could connect a pair of stereo headphones or earplugs if your TV offers a jack for them. It would have a headphone icon or say "phones" above the jack if one is provided.
Once connected, turn the TV on, lower the volume and set the TV to enable the external speakers / disable the internal speakers. This may be done via menu item selection or a small switch near the speaker terminals. Slowly increase the volume to listen to the quality or clarity of the sound coming from the speakers you connected. If they sound distorted, the problem lies with the audio amplifier in the TV. If they sound OK, then there is a problem with the speakers in the TV.
If you can't return the TV, you may have to see about using the left and right audio line out or HDMI jacks to send the audio to an external amplifier and speakers to hear the program.
I hope this was helpful and good luck! Please rate my reply. Thank you.