In addition to the mistakes that you want to avoid when using white noise for babies (which were outlined a little bit ago), there are actually a couple of other reasons why using these machines for toddlers could prove detrimental. Again, you already know that overexposure to it can lead to potential hearing and speaking delays. However, your toddler may also become accustomed to sleeping with the ambient noise and when it is taken away from them, it may make it even harder for them to fall asleep.
In general, it also is not going to be effective for all infants as some may find it agitating or disturbing. If you find that your little one is not too fond of it the first couple of times, scratch it all together.