Digital assistant compatibility: These days, it’s kind of a rite of passage for any tech gear to be compatible with voice-controlled digital assistants, and headphones are no exception. Certain high-end headphones include a microphone that you can use with voice commands to conjure up your favorite digital assistant, but you’ll need to make sure your smartphone is compatible. For example, if you own a Samsung Galaxy S8 phone (or newer version), you can use certain headphones to execute specific voice commands on your phone, such as “Check weather.”
Noise cancellation: Noise-cancelling headphones play specific tones, much like white noise, to cancel out all of the sound around you and allow you to enjoy your music uninterrupted. Noise-cancellation is an active process, so headphones with this feature require batteries. If you’re a frequent flyer, or if you’ve got a noisy commute to work each day, you’ll love noise-cancelling headphones: they’re fantastic at keeping the cacophony of the outside world at bay.
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; 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. 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." 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. 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. though such practices have received mixed response from some segments of the buying who favor the personal choice of setting their own volume levels.
The usual way of limiting sound volume on devices driving headphones is by limiting output power. This has the additional undesirable effect of being dependent of the efficiency of the headphones; a device producing the maximum allowed power may not produce adequate volume when paired with low-efficiency, high-impedance equipment, while the same amount of power can reach dangerous levels with very efficient earphones.
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. 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.
Sensitivity is a measure of how effectively an earpiece converts an incoming electrical signal into an audible sound. It thus indicates how loud the headphones are for a given electrical drive level. It can be measured in decibels of sound pressure level per milliwatt (dB (SPL)/mW) or decibels of sound pressure level per volt (dB (SPL) / V). Unfortunately, both definitions are widely used, often interchangeably. As the output voltage (but not power) of a headphone amplifier is essentially constant for most common headphones, dB/mW is often more useful if converted into dB/V using Ohm's law:
The WH-1000xM3’s excellent noise-canceling technology ranks second only to the Bose QC35 II, from the brand that has long dominated the market in terms of sheer noise-blocking abilities. That said, the Sony cans sound much better than the new bass-forward Bose option, and offer numerous features that help to create a much better overall experience.
Every single Bluetooth codec has significant quality issues—despite many creative solutions employed to make the most of the limited bandwidth the standards employ. For those keeping score at home: not a single codec available can meet wired signal quality. Though Bluetooth audio has come a long way since its noisy beginnings, it’s still not ready to replace the headphone jack. Qualcomm’s aptx HD, and Sony’s LDAC 990kbps codecs come close, but everything else falls far short of the mark.
Earphones are very small headphones that are fitted directly in the outer ear, facing but not inserted in the ear canal. Earphones are portable and convenient, but many people consider them uncomfortable. They provide hardly any acoustic isolation and leave room for ambient noise to seep in; users may turn up the volume dangerously high to compensate, at the risk of causing hearing loss. On the other hand, they let the user be better aware of their surroundings. Since the early days of the transistor radio, earphones have commonly been bundled with personal music devices. They are sold at times with foam pads for comfort. (The use of the term earbuds, which has been around since at least 1984, did not hit its peak until after 2001, with the success of Apple's MP3 player.)