i have this helmet but i don't understand how the audio works? does anyone know?

Tech Specs:

Material:

[Shell] hard plastic, Brock foam; [Liner] removable 8 Tracks winter knit 

Ventilation:

11 Vents 

Adjustability:

Sliding chin strap 

Audio:

Yes 

Volume Control:

No 

Weight:

16oz (454g) 

Recommended Use:

Snowboarding, skateboarding, wakeboarding, biking 

Manufacturer Warranty:

1 Year 

Country of Origin:

China