Amazon sells Sound Pressure Level Meters here in the USA for about $20USD.
I recommend you get one and use it whenever you are in doubt.
They make sound pressure meters for phones, but they are notoriously inaccurate because of variances in parts from one manufacturer to another.
My wife used to go to an aerobics class, the level of the music at the gym was 112db. She wore ear plugs to protect her ears.
I find that very irresponsible for a supposed get healthy place to slowly damage the ears of their patrons.
I think any place that has a volume of over 85dba should warn the customers. It’s just unethical to damage the hearing of the people who come to your business.
Bob