I’m not familiar with CC-BY, but here is a list with what you can do and what you can’t do
You can:
remix the work and sell the project as long as the sound effect is not the most important thing you sell (let’s keep it free)
use it in commercial project
do almost anything you like without any restrictions (except bellow)
give us credit for our work (is not mandatory)
use the sound in movies, games, ringtones and any other project you like
You can’t:
share the sound effect - our site will do this for you, if you wanna share with your friends share the page of the sound effect(not the link to sound effect download ). We will make money from ads, ensuring that we will add more high quality free sound effects and music(you are not going to see a sound effect that is not 320kb/s)
sell the sound(let’s keep it free), if you need to sell something create a game and sell the game along with sound effect