Voice Quality on Smart Phones Still Sucks (2014) • Hacker News Board

Re: Voice Quality on Smart Phones Still Sucks (2014)

#21

Post by thrownaway2424 » Mon, Dec 07, 2015, 5:36 PM UTC

The wideband "hd audio" codec was developed by telecom people in the 70s. The problem with mobile is that the vocoder is trying to cope with a channel having 99% packet loss and latency variance 10x over the mean. The width of the passband is the least of voice's problems.

The solution to mobile voice's problem is for the carriers to invest in a network that isn't ludicrously oversold.

Re: Voice Quality on Smart Phones Still Sucks (2014)

#22

Post by cptskippy » Mon, Dec 07, 2015, 5:45 PM UTC

I started playing around with a Lumia 530 on T-Mobile which has HD Voice and the call quality is night and day compared to my Nexus 4. Everyone I've talked to says the calls sound dramatically better and I'm not aware of anyone who has HD Voice capable phones. The noise cancelling seems to be a big thing as most people tell me that they can't tell I'm driving when I have them on speaker phone.

I didn't realize it had HD Voice and chalked it up to Nokia just knowing how to make a decent handset.

Re: Voice Quality on Smart Phones Still Sucks (2014)

#23

Post by eco » Mon, Dec 07, 2015, 6:34 PM UTC

jfountain2015 wrote: post #3

Cell quality of GSM/CDMA or others isn't good but the article ignores all the Wi-fi calling, FaceTime Audio and VOIP type calls you can make on a smart phone now. I've found that those are substantially better quality than any landline or cell.

My brother accidentally called me with Hangouts the other day and the quality was just shockingly better. I've started using it instead of a regular call where it makes sense (i.e. the other person is on hangouts+wifi too, essentially. I don't want to use up their data plan for it).

Re: Voice Quality on Smart Phones Still Sucks (2014)

#24

Post by dswiese » Mon, Dec 07, 2015, 6:34 PM UTC

but does the average customer care? similar to how Pono may have better audio quality, most people are just fine with a compressed mp3.

Its what works and its just good enough.

Re: Voice Quality on Smart Phones Still Sucks (2014)

#25

Post by kevin_thibedeau » Mon, Dec 07, 2015, 6:35 PM UTC

Cell phones actually inject "comfort noise" on the receiving end so that you can't detect when the stream is cut off during pauses in the conversation. I would venture that they just keep it on all the time, set above the actual noise in the voice data stream so that you don't hear two different noise levels.

Re: Voice Quality on Smart Phones Still Sucks (2014)

#26

Post by jhallenworld » Mon, Dec 07, 2015, 7:01 PM UTC

My pet peeve is that speaker phone quality was better on cheap flip-phone vs. what you get a smart phones. This caused me to start using a headset. For home meetings, my cordless phone's speaker phone is better than any cell phone, even though it's using "MagicJack".

Re: Voice Quality on Smart Phones Still Sucks (2014)

#27

Post by pak » Mon, Dec 07, 2015, 7:07 PM UTC

jfountain2015 wrote: post #3

Cell quality of GSM/CDMA or others isn't good but the article ignores all the Wi-fi calling, FaceTime Audio and VOIP type calls you can make on a smart phone now. I've found that those are substantially better quality than any landline or cell.

If you want to know the real reason for this, it's because normal cell calls still have to go over POTS (https://en.wikipedia.org/wiki/Plain_old_telephone_service) on the backend, which typically uses 8-bit mu-law companding of audio at 8kHz. This compresses the typical frequency range for phone calls to 300-3000Hz, which is a lot smaller than the real range of human hearing, although it covers the range used by human speech so it was considered totally acceptable before unreliable wireless packeting became the typical last leg.

VoIP, FaceTime, Skype and other IP-only technologies can use much better audio codecs, going all the way up to CD quality audio (44kHz, 16bit). This makes a huge difference when there is background noise and clipping and less than optimal transmission conditions.

(Source: I used to work for an IVR company.)

Re: Voice Quality on Smart Phones Still Sucks (2014)

#28

Post by rcthompson » Mon, Dec 07, 2015, 7:11 PM UTC

pak wrote: post #27

jfountain2015 wrote: post #3

Cell quality of GSM/CDMA or others isn't good but the article ignores all the Wi-fi calling, FaceTime Audio and VOIP type calls you can make on a smart phone now. I've found that those are substantially better quality than any landline or cell.

If you want to know the real reason for this, it's because normal cell calls still have to go over POTS ( https://en.wikipedia.org/wiki/Plain_old_telephone_service ) on the backend, which typically uses 8-bit mu-law companding of audio at 8kHz. This compresses the typical frequency range for phone calls to 300-3000Hz, which is a lot smaller than the real range of human hearing, although it covers the range used by hu…

That doesn't really explain why smartphones (and cell phones in general) sound so much worse than landlines, does it?

Re: Voice Quality on Smart Phones Still Sucks (2014)

#29

Post by zw123456 » Mon, Dec 07, 2015, 7:11 PM UTC

droopybuns wrote: post #20

feld wrote: post #7

Earlier quoted context omitted.

The problem is that there is no cross-carrier HD voice or VoLTE. If you call someone on another carrier your call quality will be flushed down the toilet. These idiots refuse to inter-operate. This is why data calling (Facetime audio, Google Hangouts(?), Skype, Whatsapp, etc) is going to crush the cellular industry. It's going to be fragmented and ugly, but at least the call quality won't suck.

>>These idiots refuse to inter-operate. Not true. There is tremendous effort in place trying to get IMS roaming/interop working. http://www.gsma.com/newsroom/wp-content/uploads/2013/04/IR.6... The problem isn't idiots refusing to interoperate, it's that the standards are implemented in subtly different ways between operators. So if you're on an AT&T or VZW network making calls to a Sprint person, you have 5 dependenc…

Exactly. The only realistic way to do it in the short term I think is to have everything fall back to G.711 but they you still end up with multiple codecs which is not idea.

Re: Voice Quality on Smart Phones Still Sucks (2014)

#30

Post by pak » Mon, Dec 07, 2015, 7:16 PM UTC

rcthompson wrote: post #28

pak wrote: post #27

Earlier quoted context omitted.

If you want to know the real reason for this, it's because normal cell calls still have to go over POTS ( https://en.wikipedia.org/wiki/Plain_old_telephone_service ) on the backend, which typically uses 8-bit mu-law companding of audio at 8kHz. This compresses the typical frequency range for phone calls to 300-3000Hz, which is a lot smaller than the real range of human hearing, although it covers the range used by hu…

That doesn't really explain why smartphones (and cell phones in general) sound so much worse than landlines, does it?

It's the combination of wireless packets dropping and the audio having to be degraded to 8bit/8kHz to pass between carriers that really brings on the terrible. It's kind of like TCP over TCP [1] -- works well enough a lot of the time, but when it fails, it fails badly because of how the two layers aren't really built for each other.

[1]: http://sites.inka.de/bigred/devel/tcp-tcp.html