What do you think about Digital Audio Broadcasting; aka HD Radio, DRM, and DAB?
I thought it might be an interesting exercise to canvass my readers from time to time on various topics. I am going to send this out via email and social media as well. I don’t know how long I will leave it open, but when it is complete, I will share the data here.
This week’s survey is ten quick questions about Digital Audio Broadcasting in the United States. If you hail from somewhere else, feel free to participate. I would be interested in those answers too.
As it turns out, 300 kbp/s or greater. At least in critical listening environments according to the paper titled Perceived Audio Quality of Realistic FM and DAB+ Radio Broadcasting Systems (.pdf) published by the Journal of the Audio Engineering Society. This work was done by a group in Sweden that made various observations with different program material and listening subjects. Each person was given a sample of analog FM audio to listen to, then they listened to various audio selections which were using bit reduction algorithms (AKA CODEC or Compression) and graded each one. The methodology is very thorough and there is little left for subjective interpretation.
In less critical listening environments, bit rates of 160-192 kbp/s will work.
I made a chart and added HD Radio’s proprietary CODEC HDC, which is similar to, but not compatible with AAC:
System
Codec
Bit Rate (kbp/s)
HD Radio FM; HD1 channel*
HDC (similar to AAC)
96 – 144
HD Radio FM; HD2 channel*
HDC
24-48
HD Radio FM; HD3 channel*
HDC
24-48
HD Radio AM*
HDC
20-60
DRM30 (MF-HF)
AAC/HE-AAC
34-72
DRM+ (VHF)
AAC/HE-AAC
700
DAB+
AAC/HE-AAC
32 – 128
DAB
MPEG II, Dolby Digital
192 – 256
Blu-ray
PCM**
≥6 Mbp/s
DVD
PCM, DTS, Dolby Digital
>800
CD-A
PCM
1,411
Web Streaming
MPEG I,II,III, WMA, AAC, etc
32-320, 128 typical
iTunes
AAC
128 – 256
Spotify
Ogg Vorbis
96 – 320
Wimp
AAC/HE-AAC
64 – 256
*Hybrid mode **PCM: uncompressed data
This is the composite Mean Basic Audio Quality and 95% confidence intervals for the system across all excerpts:
Over the years, we have simply become accustomed to and now accept low-quality audio from mp3 files being played over cheap computer speakers or through cheap ear buds. Does this make it right? In our drive to take something good and make it better, perhaps it should be, you know: Better.
