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Asterisk & HDVoice: Hearing The Siren’s Song Part 2

Audio Sample #2: The Male Voice In English

The second of my audio samples is Asterisk developer Michael Iedema from the Askozia Project. Michael is an American working in a lab in Germany. This recording gave him a chance to address the crowd at Astricon, explain his project and convey his best wishes for the show.

Michael Iedema’s greeting comparative, includes: G.711, G.722 & G.722.1C

Here again are the complete voice samples encoded four different ways. They step down in quality from uncompressed wave file down, to “super-wideband” (G.722.1C), merely “wideband” (G.722.1/G.722) and finally narrowband G.711,  just like what we once called “toll quality” on the PSTN of old.


Michael Iedema’s greeting in uncompressed wave format


Michael Iedema’s greeting in G.722.1c


Michael Iedema’s greeting in G.722


Michael Iedema’s greeting in G.711

Part 3 in this series will further examine audio samples in Norwegian, German, French, Chinese & Russian.

This Post Has 6 Comments
  1. Thanks for doing this, I’ve been thinking about something similar for months, but kept putting it on the back burner as it was obviously a low priority. The visuals and video are great for showing customers and potential customers the real advantages of VoIP’s codec flexibility.

  2. Michael, you’ve just set up and instant sales demo for Asterisk/Freeswitch system resellers and for IT folks who are pitching Asterisk or Freeswitch to their CTO’s. Thanks for doing that work and posting it online!

  3. Thanks for highlighting HD voice. I have been using HD voice and FreeSWITCH for the better part of a year and it’s been wonderful! FreeSWITCH comes ready-to-run with both Polycom Siren codecs (7 and 14) and FreeSWITCH runs them in 16kHz and 32kHz beautifully. A polycom phone connected to FS is like magic – nothing to do but enjoy REALLY high quality audio with other HD-supported polycom phones.

    FYI, we do a weekly FS conf call each Friday and we’ve got people calling in from all over the world with various codecs and signaling protocols. SIP, Skype, PSTN, etc. are presented and people using Siren, CELT, Speex, G.711a/u, etc. It’s way cool. BTW, we have an audio clip of crickets chirping that we play when there’s silence. Interestingly, the narrowband codecs don’t carry the audio. You have to be on 16k, 32k, or 48k to hear it. (Yes, we have people calling in on 48kHz CELT. It sounds incredible, assuming that the audio equipment being used is up to snuff.)

    Keep up the good work!

    1. It would be interesting to know of any other software that supports CELT. Better yet, any hardware that might support it? I still fear that lack of hardware support dooms open source codecs like SPEEX & CELT to a minor role in industry.

  4. Good point. The only software that I personally know of that says it supports CELT is Ekiga. However, our users report lots of headaches with Ekiga. YMMV.

    We use CELT for FS-to-FS setups mostly. Anthony Minessale and Brian K West connected their Macs together with FreeSWITCH and CELT. Tony fired up his guitar and did a solo and Brian listened to it over the Internet. (Tony was in WI, Brian in OK.) Brian said it sounded awesome. It probably helps that Tony has awesome audio equipment. 😉

    CELT probably won’t be widely used because Polycom his getting Siren out there at a price point that is difficult to ignore. Also, our experience with Speex is that it sucks up a lot of CPU relative to the bandwidth it saves. We have lots of Polycoms out in the wild with the “HDVoice” stamp on them, so I’m guessing that’s the way things are going to go.


    1. >>our experience with Speex is that it sucks up a lot of CPU relative to the bandwidth it saves.

      Now FS supports bv32 codec 8)
      X-lite 3.0 /win supports bv32 , speech, dv* too.

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