“The Fratzonic Chambered Exhaust—the name refers to a Dodge logo— combines various chambers underneath the Charger’s body with some woofers and mid-range speakers, all driven by a dedicated 600 W amplifier. The system is also designed to transmit vibrations into the chassis through elastomeric bushings, mimicking an internal combustion engine and its motor mounts.”
There is probably a db level in the law rather than the vague “being heard” that is much higher than the EV sound requirement.