How To Get Noise Cancellation On Any Headphones?

ordinary headphones and active noise cancellation

• no, that's not generally possible.
• so no, normal headphones can not do that, because normal headphones don't have the microphone near the ear, and they also don't have the electronics needed to do all the calculations fast enough.
• no. it's something that gets designed into the headphones themselves and requires a little bit of programming running on the headphones to process the sound.
• it's something that only the designer of the headphones can do, as it needs to be accomodated for when the headphone is developed.
• it's not something that can be added afterwards.
• no. there is no adapter box that will turn ordinary headphones into noise cancelling headphones.

why software alone does not work

• wouldnt it have to have a microphone? otherwise it wouldnt know what sounds to block out.
• from what i know of waves, the headphones would need to create the exact opposite of the actual sound being produced, otherwise it wouldn't work; it might even produce resonance or feedback, but i'm not sure of that part.
• it can't generate a generic "antinoise" wave, since there really is no specific generic noise.
• the headphones would need to know exactly what kind of noise is coming at your ears, and generate, in realtime, the opposite waveforms to try to cancel out the noise - that's why they'd need a microphone.
• as for software doing this, i'd imagine there might be too much lag between the mic picking it up, processing through the soundcard, pci bus, processor, then back, and out into the headphones.

anti-noise and inverted polarity

• the term "anti-noise" can be a bit misleading.
• what is actually happening is that a tiny microphone is recording the noise coming into your ear.
• the earphone then plays this noise too, but with inverted polarity (every plus becomes a minus and every minus becomes a plus).
• the earphone is now playing the exact opposite of the noise that arrives at your ear, which means that the sound coming out of the earphone will cancel out with the sound from the outside noise.
• you can also think of it as the earphone "sucking up" the noise sounds.

microphone position and real-time processing

• for this to work you need a microphone close to your ear (because you need to record the noise at the position where your ear is), and you need electronics that can invert the polarity (and do a bunch of other calculations) in real-time (or at least very fast), because if you play the sound only a few milliseconds to late, then it won't cancel out anymore.
• to get the maximum amount of cancellation you need to be able to match both the amplitude and phase of the noise signal at the ear with the cancellation signal sent to the speaker in the headphone.
• thus the preferred approach is to have the sensor at the ear.
• this signal, which contains both the noise and the desired signal (music?) is processed by the noise canceling system.
• the noise cancelling system knows the desired signal, the music and subtracts that signal from the total signal leaving the noise signal.
• the noise signal is then inverted and sent to the speaker, canceling the noise heard by the user.

remote microphones and phase difference

• if the microphone is a meter away from the ears then there is a phase difference between what the ear hears and what the microphone senses.
• this phase difference is a function of frequency, the higher the frequency the more phase difference.
• so you can sense and cancel low frequencies with a remote sensor but you are limited for higher frequency content.
• also, different locations receive different noise.
• you may have walked around a noisy environment an noticed a high frequency signal sounds louder and in areas and quieter in others.
• the signal likely has multiple paths to get from the source to the ear, each of these paths take a different amount of time to reach the ear.
• in some locations the direct signal plus the indirect signal will cancel, in other locations the phase will match and the noise sounds louder.
• thus a remote sensor may not hear the same noise the ear hears.
• there are limits no matter how closely you place the microphone to the ear.
• it takes time to process the correction signal, this time adds a phase change.

speaker as microphone

• technically, a speaker can function as a microphone, too, but usually not while it is producing sound.
• it might be possible to design a very sophisticated circuit that can detect external influence on the transducer while it is making sound, but i've never seen this before.
• the physical principle of a moving-coil speaker is the same as of a moving-coil microphone.
• but the construction principles are very different - loudspeakers are awful microphones, and microphones make for awful loudspeakers.
• no, you can not use the loudspeaker in the headphone to record sound in a way that lets you actually use that sound.

noise blocking and passive reduction

• also known as passive noise reduction or noise isolation
• a term like noise blocking sounds like a high-tech solution, but it’s actually very low tech.
• it can be as simple as plugging your ears with your fingers, creating a physical barrier against the noise.
• this technique, called passive noise reduction, relies on physical obstruction rather than electronic components.
• essentially, anything that covers your ears can act as a passive noise blocker, requiring no built-in technology, microphone, or power source.
• while it may be low-tech, noise blocking plays a crucial role in headphone design.
• when executed effectively, it serves as the first line of defense against unwanted sounds.
• achieving a tight seal on an earcup or a snug fit with an earbud can significantly enhance performance.

noise cancelling technology

• also known as active noise cancelling or active noise reduction
• noise cancelling, a term you’ve likely come across, is a technology that might be exactly what you’re after.
• it’s different from noise blocking and passive reduction because it involves active technology.
• noise cancelling headphones operate with powered technology, meaning they require energy, typically from a rechargeable battery, to function.
• but even without power, you still benefit from the physical noise blocking simply by wearing the headphones.
• once you power them on, that’s when the active technology comes into play.
• noise cancelling headphones monitor the sound around you, preventing the unwanted noise from ever reaching your ears based on battery power, signal processing, and various noise-blocking techniques.
• but ultimately, miniature microphones in the earcups or earbuds listen to the outside noise frequencies and emit the exact opposite signal to effectively “cancel out” both sets of sounds when the soundwaves collide.
• where noise blocking is a physical barrier to keep out sound, noise cancelling happens silently in the background, creating an audio “barrier.”

what active noise cancellation can and can’t do

• it’s a popular misconception that anc headphones cancel out all noises equally.
• they don’t.
• active noise cancellation is generally more effective on lower frequencies of sound, such as the hum of a jet engine or an air conditioner.
• it’s not as successful with human voices and other higher frequencies.
• if you travel on airplanes a lot, or if you commute every day on a bus or subway, you’ll benefit from having a set of anc headphones.
• if, on the other hand, you just want something that reduces chatter of your office colleagues or fellow starbucks patrons, conventional headphones will probably do about as good a job as noise-cancelling headphones, and they’ll often cost less.

closed headphone design and isolation

• another option to look at (assuming you haven't) is a closed headphone design that completely surrounds the ears.
• it's not exactly sophisticated technology, but it helps.
• rather than active noise cancellation just get a set of noise isolation safety headphones.
• they are as cheap as $25.
• wear them over your earbuds.