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 Earbuds 500 won’t be available until early 2020, but they might just be worth waiting for. They look to be the natural successor to the SoundSport Free, the company’s first go at truly wireless earbuds, but probably better in every way. The Earbuds 500 will likely have a longer battery life, a smaller charging case and charge via USB-C. They will be sport-focused, too, and a more affordable option to the company’s other new-age wireless earbuds, the Noise Cancelling Earbuds 700.
The Soundsport Free, released in the fall of 2017, are Bose’s first truly wireless earbuds. They utilize the same StayHear+ Sport tips as the company’s other in-ear headphones, making them naturally more sweat-resistant and more secure than AirPods. They work with the Bose Connect app, which is pretty basic but does have a “Find My Buds” feature that, when enabled, can help you find your earbuds should you misplace them.
If you’ll mostly be using headphones at your desk, install a headphone hook so you can safely stow yours when you’re not using them. Headphones can be fairly fragile, so it’s important to take care of yours and avoid tossing them around. A headphone hook gives your favorite pair a place to hang and creates a fun conversation piece for your workstation.
Headphones connect to a signal source such as an audio amplifier, radio, CD player, portable media player, mobile phone, video game console, or electronic musical instrument, either directly using a cord, or using wireless technology such as Bluetooth, DECT or FM radio. The first headphones were developed in the late 19th century for use by telephone operators, to keep their hands free. Initially the audio quality was mediocre and a step forward was the invention of high fidelity headphones.
The impedance of headphones is of concern because of the output limitations of amplifiers. A modern pair of headphones is driven by an amplifier, with lower impedance headphones presenting a larger load. Amplifiers are not ideal; they also have some output impedance that limits the amount of power they can provide. To ensure an even frequency response, adequate damping factor, and undistorted sound, an amplifier should have an output impedance less than 1/8 that of the headphones it is driving (and ideally, as low as possible). If output impedance is large compared to the impedance of the headphones, significantly higher distortion is present. Therefore, lower impedance headphones tend to be louder and more efficient, but also demand a more capable amplifier. Higher impedance headphones are more tolerant of amplifier limitations, but produce less volume for a given output level.
Garbage in = Garbage out (GIGO) is a popular phrase used to emphasize the importance of a good source. This can be the soundcard in your laptop, the quality of your portable audio player, or the CD player you’re using for music listening. Those fall into the “Source” category. The better your source is, the better the sound will be at the headphone end. This is why we are seeing more and more audiophile digital audio players (audiophile DAPs). They are expensive but they sound good.
Pairing high sensitivity headphones with power amplifiers can produce dangerously high volumes and damage headphones. The maximum sound pressure level is a matter of preference, with some sources recommending no higher than 110 to 120 dB. In contrast, the American Occupational Safety and Health Administration recommends an average SPL of no more than 85 dB(A) to avoid long-term hearing loss, while the European Union standard EN 50332-1:2013 recommends that volumes above 85 dB(A) include a warning, with an absolute maximum volume (defined using 40–4000 Hz noise) of no more than 100 dB to avoid accidental hearing damage. Using this standard, headphones with sensitivities of 90, 100 and 110 dB (SPL)/V should be driven by an amplifier capable of no more than 3.162, 1.0 and 0.3162 RMS volts at maximum volume setting, respectively to reduce the risk of hearing damage.
Music keeps me energized all day (and into the night) at work — 70% electronica/dance/DNB, 20% rock, 5% hip hip and 5% other/classical — but I’m tired of low-quality sound and I’m ready to put my money where my ears are. I want to buy a USB DAC + Headphone amp, buy headphones (or, per your recommendation, to buy 2 pair) to complement the amp and my choice of music, and get great desktop sound for around $350.
Dale: The examples listed here are good general rules, but one thing to keep in mind is in the mid-to-lower price tiers, open-back headphones aren’t nearly as common as the closed types. The smaller list of choices, and the more limited reviews of those items, could make getting a perfect fit more difficult. Sound stage and openness are often given as the advantage of the open-back types, but it’s just a general rule and some closed-back headphones excel at those properties. An important thing to consider is the music itself, since sound stage and perspective varies widely in different recordings.
The WH-1000xM3’s advanced control systems allow you to let in various levels of ambient sound, with advanced features like voice-only mode, which helps filter through vocal frequencies so you can hear your music and the voices around you while blocking out other sounds. Responsive touch controls let you navigate volume, make calls, and play and pause music with ease, all while helping to maintain a clean aesthetic. Best of all, the WH-1000xM3 offer a staggering 30 hours of battery life, providing even heavy users with days of use from a single charge, and have a quick charge feature that allows you to enjoy five hours of listening after just 15 minutes of charging.
If you just want to block out sound without active noise cancellation, good over-ear headphones will naturally do that to some extent. This is called noise isolation, and it simply works from the earcups forming a good seal over your ears to prevent outside noise from getting in. It's not as effective, but it's less expensive than active noise cancellation and doesn't require power.
Earbuds have small speakers that rest on the ear canal of the wearer. These are usually much less expensive than on-ear and over-ear headphones and reproduce the sound well. However, outside sounds, such as traffic or power tools, can get past the earbuds and interfere with your enjoyment. Earbuds also don't stay in place very well if the wearer is moving much, such as exercising. These also are lower fidelity than on-ear and over-ear headphones.