The Question Of Sidetone

Just a couple of days ago I received an email asking about side-tone. Marshall Wilgard asks;

“A VoIP expert has written that he would never buy an IP phone that did
not have “sidetone” in the handset because he would want to hear a
little of his own voice when he talked.  The Grandstream phones I use
do “not” have sidetone.  Do you believe that sidetone is important?  And
if so, which brands of IP phones have sidetone?”

As you note, sidetone is the mixing of a little of the users voice into the earpiece such that they can hear themselves as they speak. I believe that sidetone is critically important to comfortable user experience with a phone.

It’s very unnatural to not hear yourself, or hear yourself from another acoustic perspective, as you engage in conversation. Without sidetone you sound like you are very far away even though the other party sounds very near. It’s an inversion of acoustic perspective that can be discomforting.

My first experience with the lack of sidetone arose from the use of the Plantronics .Audio 480 headset. This headset features earpieces that occlude the ear canal in a manner similar to noise reducing headsets. Thus your ability to hear yourself, as well as the ambient noise of your surroundings, is diminished.

plantronics-audio480usb_cu_300

While the .Audio 480 headset has intra-aural earpieces, the same effect could be had using “big ole” circumnaural headphones that sealed well against the head. Your ability to hear yourself via natural means is diminished, so the lack of sidetone becomes obvious. The effect is awkward, but some will over time grow accustomed to it.

Soft phone programs typically do not provide sidetone, so there’s literally no way to diminish the effect when using the .Audio 480 headset. In some regards this headset is a specialty item. The lack of sidetone being the price paid to enjoy the benefit of ambient noise reduction.

I am surprised that Grandstream phone you cite does not provide sidetone. In truth, beyond some experimenting with a BT-200 in my earliest experiments with Asterisk, I have little experience with Grandstream products. What specific Grandstream model or models are you typically using?

I have recently received a couple of samples of their latest offering, the GXV-3175 Media Phone, which I hope to examine shortly. After I’ve had some time using them I’ll present my thoughts about them hereabouts.

YeaLink-SIPT28P

I’ve only ever encountered one phone that did not provide sidetone. That was the Dreamwave DP-28P, which is actually manufactured by Yealink. I bought one on E-bay just to get a sense of its feature set and build quality. At the time that I received it there was no support for sidetone, but the matter was subsequently addressed in a new firmware release.

Every other IP phone that I have ever used provided proper sidetone. That list is lengthy, including; 3com, Aastra, Avaya, Cisco, Dreamwave, Gigaset, Hitachi, Linksys, NEC, Nortel, Panasonic, Philips, Pingtel, Polycom, snom, Spectralink, Yealink & Zultys.

Sidetone is to be expected. It’s not a feature, but a core capability. Without it I was consider a product to be defective. My coworkers would not accept such a phone.

  • John Walshaw

    Cudos to you on writing about sidetone. It’s a detail that most people don’t think about.

    I agree that sidetone is a function/feature of the home/office phone (and not the headset). It’s interesting that you point out that soft phones do not typically produce sidetone and I would suggest that it is because the soft phone has no way to differentiate if a headset is being used, so to generate sidetone could defeat noise canceling and contribute to a circular audio path from computer speaker to microphone. I’d guess that most of your readers already know that so no need to explicately state it in your write up.

    On a related note, sidetone is excluded from mobile phones from some (or is it all?) manufacturers which is why you get the classic shouting conversation when a person is talking on their cell. The other sympton of lack of sidetone on mobile phones is the person taking the phone away from their ear and holding the mic close to their mouth when they talk, thinking that this will help the other person hear them. It’s funny to watch! 😀

    Perhaps the fun fact of the day is, “what is the name of sidetone’s counterpart?” Answer: “background noise” or “comfort noise”… the thing that tells you that the person you are talking to is still there when they are not talking. 🙂

    • I believe the only reason Softphones do not generate sidetone is because it would draw more attention to the latency inherent in PC-based audio processing. Generating sidetone on the headset would make more sense because the audio wouldn’t have to go through the PC and be processed and then sent back to the earpiece.

      • John Walshaw

        I don’t think that there’s really any latency for the local audio in a VoIP call. You can demonstrate this by enabling control of the Microphone in Windows Volume > Properties “Adjust volume for Playback” and then temporarily un-muting the mic. Don’t do this without a headset connected though as you’ll get an instant circular audio path. Basically, you’ll hear your voice in the headset “Karaoke style”. I agree that adding sidetone in the headset, for PC/laptop headsets only, is a perfect way to solve the issue for softphones as the softphone does not need to have any special complicated logic to detect if you have a headset or not.

  • Warmbowski

    I don’t think that not hearing sidetone is ‘unnatural’, but rather we are merely conditioned to hear it from years of using PSTN telephones. I actually never really noticed the lack of sidetone while using my .Audio 480 (until you brought it up, Michael) and it hasn’t bothered me in the least on this headset or mobile phones. I think it’s comforting to hear, but I really don’t think it’s necessary.

    That being said, I would never set up desk phones for an office phone system that doesn’t supply sidetone. I would hate to have to address all of the complaints. 😉

    • John Walshaw

      Some nice points. If you removed sidetone in the office, I think the complaint would be that “the person next to me shouts when they are on the phone.” The two functions that I think side tone plays are: it reassures you that “the person on the other end can hear me.”; your sense of being able to hear your own voice is equally balanced between both ears, i.e. compensating for one ear being blocked by the phone being pressed against it. I wonder if the addition of side tone was accidental or intensional?

  • Wow! Who knew that such an obscure topic would generate such interest. It was an email out of the blue from a reader that prompted the post. I hope that it helps them.

    In a related matter, my wife bought me a Blue Yeti microphone for Christmas last year. It’s basically a high-quality USB audio device. One of it’s many features is a headphone jack. It essentially provides zero latency sidetone for the user. The headphone feed is a mix of the speaker voice with the far-end audio.

    Might have more to say about that after I’ve used it a little more.

  • No No

    Sidetone was originally to **adjust the user** for optimal transmission over the (un-adjustable) PSTN! In other words, Bell Telephone got the person speaking into the phone to raise or lower their own voice, which they would do to make what they heard in their own earpiece “sound right”. Obviously they had to do a few experiments to figure out how loud to make the sidetone for each microphone type so folks would talk just loud enough. With the advent of carbon microphone elements and single-piece hand/head-sets, then they had to go back and do it all again plus make sure the sidetone wouldn’t feed back down the single-piece handset grip! This is not news; see for example: http://www.npr.org/templates/story/story.php?storyId=4229967

    • Thanks for the link. It’s a nice piece. Good explanation. I also found that if you Google the subject you’ll find the ITU has a number of documents that describe the sidetone levels required to achieve desirable MOS scores.

      • John Walshaw

        I think it’s great that you wrote The Question Of Sidetone. It’s also nice to see who came out of the woodwork to chip in on discussing it. Some really great points all around.

  • Andrew

    Thanks for sharing all the info. Do you have any reviews of Grandsteram products? According to the user manual the Grandstream GXP phones do “support side tone”. Which specific model phones was the email you received referring to? I have not use any Grandstream phones so I can’t comment about how well they work, but they seem to be priced reasonably enough for soho users and the GXP 2010 supports G.722 wideband, and GSM among many other codecs and features. Maybe Marshall Wilgard is using a consumer grade Grandstream phone, or needs to update his firmware.

    • I think it’s odd that he reports problems with lack of side tone. The lack of it is certainly a problem, but it’s very rare to find it missing in established commercial products. I have a pair of GXP-3175 phones on-house for eval. While not entry level, these appear to have no issue with side tone. Admittedly, I’ve only used them very briefly to this point.

      • Andrew Dixon

        Interesting..
        I always wondered why the flat sponge headsets were always my first choice as I couldnt seem to find an in ear model that did the job.
        It will be interesting to see your review on the 3175. I have a couple things on the wish list but I will leave you to take an unbiased assessment of it first.

  • The new GXP 2100 and the GXP 2110 do not have the side tone. This is Grandstreams replacement model for the GXP 2000 and the GXP 2010. We have installed a bunch of the older models which DID have the sidetone and the customers (and out office) loved them. We have only placed about 50 of the new models and have had several complaints. The new models include HD sound but other then not having side tone, it is hard to tell any difference except for the improved speaker phone. We have contacted and am waiting for a response from Grandstream and asked about the sidetone and if they had a fix for it. In the meantime we are only buying the old models (which are drying up) and are replacing the new ones that we have installed with customers. Its a shame, the 2010 was really a good reliable phone with great features and lots of BLF buttons. Those phones where greatly improving Grandstreams reputation among the industry. How Grandstream could have not had a solution to this before releasing this product and discontinuing the old one shows they have not quite got it together and may not be ready to join the majors such as Polycom and Cisco. I assume that most of their new phones with “HD” do not have the side tone but have not tested them all. We are now searching for a replacement product that can meet our customer needs.

    • Hmmm…the lack of sidetone is a problem. Earlier this week Grandstream agreed to appear as a guest on a future VUC call. This is a question that we should put to their representative.

  • Jane Smith

    I know the thread is old, but everyone has missed one important issue. There are cases where ZERO sidetone is not defective, it’s desirable. When making a podcast or radio show, *all* broadcasters use a $400 piece of equipment to remove sidetone from phone calls, or latency in the system will create echo. I am currently researching phones that have adjustable sidetone for this reason.

    • mjgraves

      While that’s true, in the broad scheme of things those are edge cases. A desk phone that will be used by a person needs sidetone to be comfortable.

      I have since found that Polycom phones have adjustable sidetone. The adjustment must be done in an XML config file. However, you can find the XML snippet that defines the desired setting and upload it to the device from the web GUI. That will add the parameter to the phone’s local configuration. Thereafter it will persist through a reboot. No provisioning server required.

      Soft phone are the better solution, never any sidetone involved. Although I accept that adding the variability of another computer into the mix might not be a benefit.