As the name gives away, these have an on-ear design instead of the over-ear design of most of Bose’s other offerings. The trade-off is that the On-Ear Wireless Headphones won’t be able to block out ambient noises as well, but some people might find them more comfortable. Plus they’re well cheaper than most other Bose wireless headphones. It should be noted that many reviewers, including Sound Guys, have praised the sound quality of these headphones.
Headphones can prevent other people from hearing the sound, either for privacy or to prevent disturbing others, as in listening in a public library. They can also provide a level of sound fidelity greater than loudspeakers of similar cost. Part of their ability to do so comes from the lack of any need to perform room correction treatments with headphones. High-quality headphones can have an extremely flat low-frequency response down to 20 Hz within 3 dB. While a loudspeaker must use a relatively large (often 15" or 18") speaker driver to reproduce low frequencies, headphones can accurately reproduce bass and sub-bass frequencies with speaker drivers only 40-50 millimeters wide (or much smaller, as is the case with in-ear monitor headphones). Headphones' impressive low-frequency performance is possible because they are so much closer to the ear that they only need to move relatively small volumes of air.
Today they are typically used only in in-ear headphones and hearing aids, where their high efficiency and diminutive size is a major advantage.[20] They generally are limited at the extremes of the hearing spectrum (e.g. below 20 Hz and above 16 kHz) and require a better seal than other types of drivers to deliver their full potential. Higher-end models may employ multiple armature drivers, dividing the frequency ranges between them using a passive crossover network. A few combine an armature driver with a small moving-coil driver for increased bass output.
Active noise-cancelling headphones use a microphone, amplifier, and speaker to pick up, amplify, and play ambient noise in phase-reversed form; this to some extent cancels out unwanted noise from the environment without affecting the desired sound source, which is not picked up and reversed by the microphone. They require a power source, usually a battery, to drive their circuitry. Active noise cancelling headphones can attenuate ambient noise by 20 dB or more, but the active circuitry is mainly effective on constant sounds and at lower frequencies, rather than sharp sounds and voices. Some noise cancelling headphones are designed mainly to reduce low-frequency engine and travel noise in aircraft, trains, and automobiles, and are less effective in environments with other types of noise.
The thermoacoustic effect generates sound from the audio frequency Joule heating of the conductor, an effect that is not magnetic and does not vibrate the speaker. In 2013 a carbon nanotube thin-yarn earphone based on the thermoacoustic mechanism was demonstrated by a research group in Tsinghua University.[22] The as-produced CNT thin yarn earphone has a working element called CNT thin yarn thermoacoustic chip. Such a chip is composed of a layer of CNT thin yarn array supported by the silicon wafer, and periodic grooves with certain depth are made on the wafer by micro-fabrication methods to suppress the heat leakage from the CNT yarn to the substrate.[citation needed]
Using headphones at a sufficiently high volume level may cause temporary or permanent hearing impairment or deafness. The headphone volume often has to compete with the background noise, especially in loud places such as subway stations, aircraft, and large crowds. Extended periods of exposure to high sound pressure levels created by headphones at high volume settings may be damaging to hearing;[25][26] Nearly 50% of teenagers and young adults (12 to 35 years old) in middle and high income countries listen to unsafe levels of sound on their personal audio devices and smartphones.[27] however, one hearing expert found in 2012 (before the worldwide adoption of smartphones as the main personal listening devices) that "fewer than 5% of users select volume levels and listen frequently enough to risk hearing loss."[28] The International Telecommunication Union recently published "Guidelines for safe listening devices/systems" recommended that sound exposure not exceed 80 decibels, A-weighted dB(A) for a maximum of 40 hours per week.[29] The European Union have also set a similar limit for users of personal listening devices (80 dB(A) for no more than 40 hours per week) and for each additional increase of 3-dB in sound exposure, the duration should be cut in half (83 dB(A) for no more than 20 hours, 86 dB(A) for 10 hours per week, 89 dB(A) for 5 hours per week and so on. Most major manufactures of smartphones now include some safety or volume limiting features and warning messaging in their devices.[30][31] though such practices have received mixed response from some segments of the buying who favor the personal choice of setting their own volume levels.

What I’m saying here is that it’s better to own three $100 headphones than one $300 headphone. Or three $300 headphones than one $900 headphone. Why? Because most people don’t limit their playlist to strictly one genre. And following the logic from Rule #2, the right headphone-music pairing is going to be better than one expensive headphone paired to the wrong music.

Noise cancelation for kids? Doesn’t that mean they’ll ignore their parents even more often than they already do? Perhaps, but it’s a risk worth taking if it means your kids’ hearing will be protected over the long-term. That’s exactly the premise behind the Puro PuroQuiet headphones. Not only are they wireless and great-sounding, but they also come equipped with a software limiter that keeps the volume at or below 85dB, which is considered the maximum volume that children should be exposed to for prolonged periods. The noise-canceling feature means they’ll actually be able to listen to lower (therefore safer) volumes.
An electret driver functions along the same electromechanical means as an electrostatic driver. However the electret driver has a permanent charge built into it, whereas electrostatics have the charge applied to the driver by an external generator. Electret and electrostatic headphones are relatively uncommon. Original electrets were also typically cheaper and lower in technical capability and fidelity than electrostatics. Patent applications from 2009-2013 have been approved that show by using different materials, i.e. a "Fluorinated cyclic olefin electret film", Frequency response chart readings can reach 50 kHz at 100db. When these new improved electrets are combined with a traditional dome headphone driver, headphones can be produced that are recognised by the Japan Audio Society as worthy of joining the Hi Res Audio program. US patents 8,559,660 B2. 7,732,547 B2.7,879,446 B2.7,498,699 B2.
Case in point: the Koss PortaPro headphones first hit the market in 1984 and have become such a favorite with audiophiles that the company leaves the design (and the price tag) untouched. You can still pick one up for less than $50, and they come with a lifetime warranty, no receipt necessary. Check out our favorite budget headphones for more selections.
Dale: There are so many types of amplifiers (and DAC’s with amplifiers) that there is no shortcut for studying all of the options, unless you settle for the most generic approach. Important things to consider are power – if you don’t have enough power for your headphone and the dynamics in the music, clipping will result. Sometimes the clipping is “soft” and not readily noticed, but eventually you would discover that much of the detail goes missing or gets veiled with limited dynamics. Another consideration is whether to use a DAC, which may be a separate DAC or built into the same enclosure as the amp. Most DACs will improve the sound over the DACs that are built into computers, but when a DAC is available to replace the DAC built into most cellphones and low to mid-priced music players, you can usually expect a much greater improvement.
Headphones (or head-phones in the early days of telephony and radio) traditionally refer to a pair of small loudspeaker drivers worn on or around the head over a user's ears. They are electroacoustic transducers, which convert an electrical signal to a corresponding sound. Headphones let a single user listen to an audio source privately, in contrast to a loudspeaker, which emits sound into the open air for anyone nearby to hear. Headphones are also known as earspeakers, earphones[1] or, colloquially, cans.[2] Circumaural ('around the ear') and supra-aural ('over the ear') headphones use a band over the top of the head to hold the speakers in place. Another type, known as earbuds or earpieces[1] consist of individual units that plug into the user's ear canal. A third type are bone conduction headphones, which typically wrap around the back of the head and rest in front of the ear canal, leaving the ear canal open. In the context of telecommunication, a headset is a combination of headphone and microphone.