Active Noise Cancellation - Page 1
Forum section: electronics / beginners

author: David Cutcher CEG
author_rank: Contributor
timestamp: April 25, 2019, 07:36:10 pm
content: I'm looking for anActive Noise Cancellation Circuitfor headphonesthat I can build with standard hard wire stock. To cancel out loud voices around me.I see that Digikey lists a dedicated IC made by AMS (AS3410-EQFP) but not stocked. That's a red flag for me.Suggestions?David Cutcher "Certified Evil Genius"

author: Audioguru
author_rank: Super Contributor
timestamp: April 25, 2019, 08:04:27 pm
content: You forgot to say what the noises are and what produces them.Hum or hiss from a loudspeaker or headphones?Traffic noises?Many little kids at a playground?Noise cancelling headphones use a microphone to pickup noises outside the headphones then use an electronic circuit to add the noise out-of-phase to cancel the noise heard inside the headphones. Is that what you want?

author: David Cutcher CEG
author_rank: Contributor
timestamp: April 26, 2019, 12:04:22 am
content: I do understand the concept. And have tried to build it using an inverting amplifier. But realize I don't know enough to get it precisely out of phase.My apologies for not including specs.I'm looking to build an active noise cancelling circuit that blocks in normal speech range. My step daughter is developmentally delayed, and speaks her immediate thoughts aloud, continuously. Not making light of the situation, but I can turn up the volume of my own music just so far.This would be different than ones blocking jet engine noise or working in a shop situation. Those actually allow some normal speech range through.David Cutcher "Certified Evil Genius"

author: Marco
author_rank: Super Contributor
timestamp: April 26, 2019, 01:09:14 am
content: Not sure if a headset is the best solution, earplugs work better than noise cancellation and earplug+audio combinations are affordable.Less isolating visually.

author: David Cutcher CEG
author_rank: Contributor
timestamp: April 26, 2019, 01:14:53 am
content: Yes, earplugs are affordable. Not as much fun.But I want to build and learn an area I'm not familiar with.DC

author: borjam
author_rank: Unknown
timestamp: April 26, 2019, 07:11:23 am
content: ANC works best for low frequencies. As the frequency gets higher, hence wavelength is shorter, phase becomes more critical.For example I own a pair of high end ANC heaphones (Sennheiser PXC-550) and their ANC mainly affects frequencies below, say, 1 KHz. For frequencies above 1 KHz the key is the good old mechanical isolation.So, if voice is what really bothers you I would recommend good mechanical isolation headphones instead. ANC attenuates voice a bit, but I can hear voices around perfectly (albeit attenuated, because the lower end is reduced by the ANC).ANC does wonders with airplane, train or bus cabin hum, the typical and annoying AC hum and other low frequency noises present in crowded buildings, etc.

author: Marco
author_rank: Super Contributor
timestamp: April 26, 2019, 11:22:55 pm
content: Here'san interesting paper for a noise cancelling chair with decent performance, you could do the math on a cortex M4/M7 ... audio is not a lot of data by modern standards.Unless you are some genius wizard I don't think you'll replicate that research quickly, so just get some Peltor 2600N's or Isotunes wired earplug/headphones in the mean time.