Cardo Freecom 4+

[ST Gui]

I don't think that it uses the boom mike for ambient sound. I have noticed that if you rub your finger along the unit while it is in ambient mode, the sound is picked up at that point and not the boom mike.

I think what you're hearing is the microphonics of your rubbing of the unit being transmitted along the boom and then being picked up by the mike. Or it might be the vibrations of rubbing the unit being transmitted to the helmet shell much like the movement/vibration of headphone cables being transmitted along the cable to the body of the headphones.

The 20S instruction manual makes no mention of a second/buit-in microphone and depicts the boom mic outside of the helmet. I keep the mike inside the helmet to reduce wind noise and better pick up my voice.

Maybe you could repeat your test with the mike removed. I bet that eliminates the sound coming through the speakers though microphonics may still be heard. I'd try it but my helmet is far from handy at the moment.

 

[Andrew Shadow]

The 20S instruction manual makes no mention of a second/buit-in microphone ......

I knew that there is no ambient microphone listed but I have noted that if it is in ambient mode while riding, you will very loudly hear the wind noise, the whine of the tires passing you, the sound of the exhaust from large trucks, etc.. You can even hear the ST engine whine very clearly in ambient mode. None of these sounds are audible to someone listening to you over the intercom using the boom microphone regardless of whether the helmet visor is open or closed. The difference is considerable, which is why I thought that there must be another microphone but I don't know this for a fact. No riding here yet so the gear is still stored but some experimentation is required I guess.

 

[Larry Fine]

It's easier to understand if you know how noise-canceling works.

The boom has two microphones, both of which pick up ambient noise, but one picks up your voice better.

When communicating, the common sounds are rejected, so your voice is heard above the ambient noise.

To hear ambient sounds, all they have to do is direct the mic facing away to your ears, without canceling.

 

[Andrew Shadow]

Maybe you could repeat your test with the mike removed. I bet that eliminates the sound coming through the speakers though microphonics may still be heard. I'd try it but my helmet is far from handy at the moment.

To hear ambient sounds, all they have to do is direct the mic facing away to your ears, without canceling.

I didn't remove the boom microphone because I didn't want to bother removing the base from the helmet and taking it apart but, out of curiosity, I spent a couple of minutes experimenting with some ear-bud speakers playing music from an MP3 player.

With the unit not in ambient mode, I placed the speakers in proximity to the boom microphone's forward and rear facing sides to confirm that it picked up the music and that I could hear it in the helmet speakers. I then put the ear-bud speakers next to the main unit on the side of the helmet and the sound level was diminished as the source was no longer close to the boom microphone.

I then put the unit in to ambient mode and did the same tests all over again. With the unit in ambient mode, obstructing the boom microphone had no effect on the volume. However, the volume of the music was significantly louder when the speakers were placed next to the main unit on the side of the helmet as opposed to near the boom microphone. As a matter of fact, opening the rubber cap for the USB charging port and directing the speakers in to that opening significantly increased the sound level. All ambient sound sources, the television, the dishwasher, etc., were all louder with this cap open.

A conclusive test this was not because I did not remove the boom microphone to eliminate it completely. However, the increased volume achieved by placing the speakers near the main unit, as well as the further increased volume by opening the USB cap, certainly gives the impression that there is another microphone inside the main unit that is used for ambient mode.

 

[Larry Fine]

I admit that I was guessing.

 

[ST Gui]

I didn't remove the boom microphone because I didn't want to bother removing the base from the helmet and taking it apart but, out of curiosity, I spent a couple of minutes experimenting with some ear-bud speakers playing music from an MP3 player.

That would certainly allow for the possibility of an internal mic. Since I wouldn't be interested in dismounting my 20S either I sent off an inquiry to Sena hoping they'll comment.

We'll see if and when they get back to me.

 

[Andrew Shadow]

That would certainly allow for the possibility of an internal mic. Since I wouldn't be interested in dismounting my 20S either I sent off an inquiry to Sena hoping they'll comment.

We'll see if and when they get back to me.

Doing a quick search, I read several posts on several forums from others who are certain that there is an internal microphone for the ambient mode. Several have asked Sena and they have never responded to this question.

I always found the ambient mode quite useless as what it picks up can't be heard as there is no volume to it. From what I read, it worked much better with the early versions of the firmware. Opening the USB cap was the only recommendation for improving it.