Yes! I've seen reviews of these and they seem essential since kids may=20 be touching robot. I'll have to DIY one though because space is tight. Cheers, -Neil. On 1/21/2019 6:16 PM, Allen Mulvey wrote: > Several years ago I made a video for the Sunday School at my > church. Background noise was a problem so I bought a > relatively cheap shotgun mic with a rubber suspension mount > and it made a huge difference. > > Allen > > -----Original Message----- > From: piclist-bounces@mit.edu > [mailto:piclist-bounces@mit.edu] On Behalf Of Neil > Sent: Monday, January 21, 2019 5:34 PM > To: Microcontroller discussion list - Public. > Subject: Re: [EE] Microphone speech bandpass filter > > Yes, I'm working on the physics side of it... currently > tinkering with > various-sized tubes (different lengths and diameters). The > mic will be > suspended in the middle of the pipe near the back end. I've > yet to > tinker with wind diffusers such as foam at the front end of > the pipe, > and I would like to experiment with a parabolic reflector > but haven't > sourced one yet. > > Noise cancelling would be great, but I know it would take a > lot more > time than I have currently, and I won't have access to the > actual > environment available until d-day. I'm using other crowded > spaces > test, trying to see if I can isolate one person's voice. > FWIW, the > person speaking to the robot does not need to be perfectly > isolated... > the operator just needs to hear the person clearly enough to > understand > them. Asking them to repeat what they said is not an > option. > > Cheers, > -Neil. > > > On 1/21/2019 1:59 PM, David Van Horn wrote: >> LTSpice would be good for modeling the filter. >> The filter is a good idea, but making the pickup more > directional would be a big plus. >> You might consider a noise canceling mic summed in with > the other one. >> It would take some experimentation to get right, phase and > amplitude errors determine how well it will work. >> -----Original Message----- >> From: piclist-bounces@mit.edu On > Behalf Of Neil >> Sent: Monday, January 21, 2019 11:09 AM >> To: Microcontroller discussion list - Public. > >> Subject: [EE] Microphone speech bandpass filter >> >> Hi all, >> >> Background: I built a robot that will drive around and > chat (remote >> operator) with kids in a crowd, but I've been agonizing > over the audio, specifically from the kid (robot-side) to > the remote operator. I ran some tests with a cardioid > condenser handheld mic/transmitter (Shure >> SM58 FWIW) and it picks up voice well, but I'd like it to > get less surrounding noise. The Shure won't fit eaily > inside the robot so currently looking at just using a > condenser element and transmitting with a Samson Concert 88 > TX/RX. >> I'm tinkering with physically directing the noise with > pipes/tubes and will try a parabolic reflector, but I'm also > wondering about using a bandpass filter just after the mic, > to be more selective for human voice. POTS is around 3k > bandwidth (300Hz - 3300Hz), which is great for > voice/speech/talking. Would this be an ideal range for > limiting speech frequencies here also? >> For the actual filter, I was thinking about just going > passive so I don't have to worry about split power supplies, > but IIRC for something low-power like this, I should be able > to create a virtual ground with a voltage divider and an > op-amp follower. Shouldn't active be better for this? > FWIW, I have 12V available on the robot. >> Any other thoughts? Time is of the essence here, so > simpler is good, but it has to work well. >> Cheers, >> -Neil >> >> >> -- >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list > archive View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .