GameSpot: (sound score 10 of 10)
Despite the fact that the actual dialogue among the game's inhabitants is made to sound like complete gibberish, The Sims sounds superb overall. You can't make out exactly what they're saying, but you can easily infer their intentions from the tone of their voices. Sims will speak, then pause and clear their throats while they're thinking of what to say next, yelp in pain when they cut themselves preparing a meal, or tell naughty limericks as jokes. Sims also interact with their surroundings, and everything from coffee makers to toilets sounds realistic, clear, and in some cases downright hilarious, like the slapstick noises of the TV cartoons. The Sims' music is also excellent; even though much of it consists of vapid easy-listening, those unassuming tunes provide a perfect ironic contrast in the background against whatever havoc your sims are wreaking on center stage
Game Spy:
The sound is also a pleasure--on balance. The music in the game is effective and entertaining, providing an ambient background that's pleasant to listen to. You can even change the stations if you like to tune in Rock, Latin, Classical, or Country.
Gamecenter:
The Sims is one of those rare games in which the sound actually outshines the graphics. Every action has a corresponding sound, whether it be the whacking of the knife against the cutting board, or the blaring of music from the stereo. The dialogue, which is made up of gibberish, is humorous, especially when your Sims are miserable and trying to get your attention.
From Yahoo Game Audio Pro Forum:
I love the Muzak style in The Sims. It makes me laugh just hearing it. Especially with all of the crazy stuff happening on screen.