Are there any existing codecs or modes, or are hams experimenting with modes that provide better than telephone/radio quality sound?
It seems like there's a lot of opportunity here to stick to narrow band modulation schemes but at the same time provide better voice quality than what's currently experienced using cheap FM transceivers.
Are the newer digital modes Icom and others coming out with better than telephone/radio quality?
Because of the US Federal mandate to make efficient use of spectrum, the digital modes (including, but not limited to, AMBE/D-Link Voice, APCO-25, Codec2 and FreeDV ) are mostly moving in the other direction, towards equivalent intelligibility within less spectrum.
Are there any existing codecs or modes, or are hams experimenting with modes that provide better than telephone/radio quality sound?
Here in Canada it's pretty much only D-Star you hear about. Some hams in USA are experiencing with P25 I think, but only in conventional mode (no trunking). Both technologies use vocoders from DVSI inc, respectively AMBE and IMBE/AMBE+2 chips. I think right know Yaesu is coming with a new digital technology (12.5 kHz C4FM FDMA modulation) which looks like a P25 ham adaptation. According to this post, they are using AMBE+2 too. D-Star sound quality is terrible in comparison of P25. P25 sounds a bit better than telephone when properly configured but lesser than analog FM or radio (you're talking about AM/FM radio I guess?), especially with background noises (sirens, music, chatter, etc).
Are the newer digital modes Icom and others coming out with better than telephone/radio quality?
None that I'm aware of. I work with D-Star and P25 and Tetra. The two latters having the best quality/intelligibility to my ear. D-Star being to worst. The use of proprietary technology (DVSI vocoders) in D-Star and Yaesu's digital gear makes many radio amateurs angry because it's not aligned with the "openness" philosphy shared in ham communities.
I know there is a new codec, open source, named Opus that could be used in ham radios, but I don't know if anyone checked it seriously as an alternative to DVSI proprietary vocoders.
