Do it Yourself (DIY)  
MP3 Adapter . Use your factory head unit's AUX input for Mp3 players.
Shock absorber header ring
Simple way of increasing ride comfort
Tire Exchange
Original Tires are Bridgestone Potenza RE040 185/55 R14 . These sporty tires are 
quite noisy, especially when cold
Sound Deadening
Jazz road noise is sometimes disturbing, see how to make it more silent
Wind Noise Reduction
On highway wind noise is sometimes disturbing, it can be reduced with simple methods.
Ziebart Underbody Coating
Still not satisfied with road noise levels. Try this
  Cabin filter removal and cleaning
If you live in a dusty area, every 2-3 months you need to this
Pete Gildenhuys from Pretoria, South Africa has made some extreme sound damping to his Jazz. Thanks for his contribution.
Important: All DIYS here are your self responsibility. If you feel not confident what you're doing, don't try them. It might void your car warranty or might cause some injuries etc. whatever. It's all up to you.