Yes they can be hard to hear. There are a few technical challenges working against us making the buzzer in Pacif-i louder. Firstly there isn't a lot of space for a large buzzer, the pacifier is effectively hermetically sealed and this makes it difficult for sound to escape and we are powering the pacifier with a coin cell where we are aiming to get 6 - 12 months use out of it.
Overcoming these challenges has resulted in a buzzer that can be difficult to hear at times, especially when there is a lot of background noise. But we have designed Pacif-i so that you don't really need to hear the buzzer to operate it or find it if it is lost.
It is reasonably straight forward to determine whether the pacifier is on or off by looking at the Pacif-i app. If it is off, then a simply push of the button on Pacif-i will turn it on and it will appear in the app. Likewise pushing and holding the button on Pacif-i down for 5 seconds will turn it off. You can do this without having to hear the beeps.
Also the app has a proximity indicator that will help you find Pacif-i without having to activate its buzzer. As you move closer the proximity indicator will get stronger, right up to the point where the smartphone is literally touching the pacifier.