According to Santa Clara County's noise ordinance, no one may generate sound that, at the point of crossing onto another person's residential property, exceeds 45 decibels between 10pm and 7am (55 decibels between 7am and 10pm). What this means is that amplified sound must be curtailed beginning at 10pm.
Here are some things you can do to ensure that noise doesn't leave your party.
Another thing to do is tell your neighbors that you will be having a party, and if you feel comfortable with it give them your number so they can let you know if it gets too loud. If your party is too loud it may be shut down, and you could be cited by the police. Parties that generate noise that is noncompliant with the policy/ordinance are subject to being shut down by University personnel and/or police.