Sound can be a weapon, deterrent, and a defense. There are different items that utilize sound that can be very useful to real life superheroes.
Sound can help scare away criminals and attackers by bringing attention to them. The last thing a criminal or attacker wants is people to start paying attention to what they are doing. A loud enough sound can slightly stun and disorient a person.
A cheap and effective tool to have is a whistle. There is a reason police officers have them.
You can buy a run of the mill whistle anywhere, but for a RLSH I would advise buying the loudest whistle in the world the Storm Whistle. This is the loudest whistle in the world going up to 120 decibels.
You can buy and read about them here
Personal Alarms are a good choice. They can go up to 130 decibels and many are activated by a pull pin. Some even come with flashing and strobing light to get extra attention.
Here’s a few to check out
Another item that can be used on different occasions is a bullhorn/megaphone . It can be used if you are doing events, demonstrations, or protests. It is a great way to get attention and have the public hear you.
I don’t suggest doing this, but I have used it to help drive dealers out of their spots by bringing unwanted attention to them.
A simple online search will help you find one. Just make sure to see what wattage it has.
Keep sound on your side and stay safe.