How to reduce high speed turbo blower noise level?

Yes, it's not how to reduce roots blower noise level, it's how to reduce turbo blower noise level.

Normally turbo blower noise level is less than 80 dba when roots blower noise level is more than 90 dba, some user are still not satisfied, they want the noise level below 60 dba or even 50 dba.

Turbo blower ZCJSD has it's own suggestion to reduct turbo blower noise level:
Wrap the outlet pipe with sound-absorbent material, please see below photo:

ZCJSD turbo blower is the first and biggest air bearing turbo blower manufacturer in China and biggest turbo blower manufacturer in the world with annual production of 1000 sets from 20HP to 400HP.