system sound delay RDP session with Windows server 2012 R2 standard

I have the following problem during a RDP session with a Microsoft Terminal Server 2012 R2 standard:
when i produce a system sound, the delay could be up to 15 seconds before I hear the cound on the client side.
making immediately a second system sound, the delay is minimal,
When i wait about 10 minutes, the delay could be again 5-15 seconds.
This problem occurs both with Windows 7 and Motorola Scanners

I also noticed that after making a sound on the first device, there is also no delay when making immediately a sound on a second RPD session.

I tried different settings for audioqualitymode or audiocapturemode, no luck

henk