Noise-cancelling headphones

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Noise-cancelling headphones alongside a carry case Bose QuietComfort 25 Acoustic Noise Cancelling Headphones with Carry Case.jpg
Noise-cancelling headphones alongside a carry case

Noise-cancelling headphones are headphones which suppress unwanted ambient sounds using active noise control. This is distinct from passive headphones which, if they reduce ambient sounds at all, use techniques such as soundproofing.

Contents

Noise cancellation makes it possible to listen to audio content without raising the volume excessively. In the aviation environment, noise-cancelling headphones increase the signal-to-noise ratio significantly more than passive noise attenuating headphones or no headphones, making hearing important information such as safety announcements easier. [1] Noise-cancelling headphones can improve listening enough to completely offset the effect of a distracting concurrent activity. [2]

Theory

Simplified graphical depiction of active noise reduction Active Noise Reduction.svg
Simplified graphical depiction of active noise reduction

To cancel the lower-frequency portions of the noise, noise-cancelling headphones use active noise control or ANC. A microphone captures the targeted ambient sounds, and a small amplifier generates sound waves that are exactly out of phase with the undesired sounds. When the sound pressure of the noise wave is high, the cancelling wave is low (and vice versa). The opposite sound waves collide and are eliminated or "cancelled" (destructive interference). Most noise-cancelling headsets in the consumer market generate the noise-cancelling waveform in real time with analogue technology. In contrast, other active noise and vibration control products use soft real-time digital processing. According to an experiment conducted to test how lightweight earphones reduced noise as compared to commercial headphones and earphones, lightweight headphones achieved better noise reduction than normal headphones. The experiment also supported that in-ear headphones worked better at reducing noise than outer-ear headphones. [3]

Cancellation focuses on constant droning sounds like road noise and is less effective on short/sharp sounds like voices or breaking glass. It also is ineffective in eliminating higher frequency noises like the sound of spraying. Noise-cancelling headphones often combine sound isolation with ANC to maximize the sound reduction across the frequency spectrum. Noise cancellation can also be used without sound isolation to make wanted sounds (such as voices) easier to hear. Noise cancellation to eliminate ambient noise is never passive because of the circuitry required, so references to passive noise cancellation actually are referring to products featuring sound isolation.

To prevent higher-frequency noise from reaching the ear, most noise-cancelling headphones depend on sound isolation or soundproofing. Higher-frequency sound has a shorter wavelength, and cancelling this sound would require locating devices to detect and counteract it closer to the listener's eardrum than is currently technically feasible or would require digital algorithms that would complicate the headphone's electronics. [4]

Noise-cancelling headphones specify the amount of noise they can cancel in terms of decibels. This number may be useful for comparing products but does not tell the whole story, as it does not specify noise reduction at various frequencies.

In aviation

By the 1950s, Dr. Lawrence Jerome Fogel created systems and submitted patents regarding active noise cancellation in the field of aviation. This system was designed to reduce noise for the pilots in the cockpit area and help make their communication easier and protect hearing. Fogel is considered to be the inventor of active noise cancellation, and he designed one of the first noise-cancelling headphones systems. Later on, Willard Meeker designed an active noise control model that was applied to circumaural earmuffs for advanced hearing protection. Noise-cancelling aviation headsets are now commonly available. [5] [6]

In 1989, Bose Corporation introduced its "Series I Aviation Headset" which became the first commercially available ANR headset. It included a noise-cancelling function and was powered either by NiCad batteries (with a claimed battery life of 8 hours) or by power from the aircraft. Series I aviation headsets are distinguished by the clear windows on the earcups or by noting that the on/off switch and volume control are located on the separate control module. [7]

Several airlines provide noise-cancelling headphones in their business and first-class cabins. Bose started supplying American Airlines with noise-cancelling headphones in 1999 and started offering the "Quiet Comfort" line for the general consumer in 2000. Noise cancelling is particularly effective against aircraft engine noise.[ citation needed ] [7]

As a sleeping aid

Noise-cancellation headphones have been used as sleeping aids as well. [8] Both passive isolating and active noise-cancellation headphones or earplugs help to achieve a reduction of ambient sounds, which is particularly helpful for people suffering from insomnia or other sleeping disorders, for whom sounds such as cars honking and snoring impact their ability to sleep. For that reason, noise-cancelling sleep headphones and ear plugs are designed to cater to this segment of patients. [9]

In hospitals

The use of noise-cancelling headphones for patients in intensive care units has been implemented to reduce the amount of noise exposure that they face while in a hospital environment. Active noise control technology is shown to have a relationship with sleep disturbance, delirium, and morbidity, therefore bringing up concerns about lowering the levels of noise for patients receiving care. [10]

Health and safety

There is a general danger that listening to loud music in headphones can distract the listener and lead to injury and accidents. [11] [12] Noise-cancelling headphones add extra risk. Several countries and states have made it illegal to wear headphones while driving or cycling. [13]

It is not uncommon to get a pressure-like feeling when using noise-cancelling headphones initially. This is caused by the lack of low-frequency sounds as being perceived as a pressure differential between the inner and outer ear. [14] [15] [16]

Autism

A December 2016 study from the Hong Kong Journal of Occupational Therapy found that noise-cancellation headphones helped children with autism spectrum disorder cope with behaviors related to hyper-reactivity and auditory stimuli. [17]

Drawbacks

The active noise control requires power, usually supplied by a USB port or a battery that must occasionally be replaced or recharged. Without power, some models do not function as regular headphones. Any battery and additional electronics may increase the size and weight of the headphones compared to regular headphones. The noise-cancelling circuitry may reduce audio quality and add high-frequency hiss, although reducing the noise may result in higher perceived audio quality. [18]

See also

Related Research Articles

<span class="mw-page-title-main">Binaural recording</span> Method of recording sound

Binaural recording is a method of recording sound that uses two microphones, arranged with the intent to create a 3D stereo sound sensation for the listener of actually being in the room with the performers or instruments. This effect is often created using a technique known as dummy head recording, wherein a mannequin head is fitted with a microphone in each ear. Binaural recording is intended for replay using headphones and will not translate properly over stereo speakers. This idea of a three-dimensional or "internal" form of sound has also translated into useful advancement of technology in many things such as stethoscopes creating "in-head" acoustics and IMAX movies being able to create a three-dimensional acoustic experience.

<span class="mw-page-title-main">Headphones</span> Device placed near the ears that plays sound

Headphones are 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 earphones or, colloquially, cans. Circumaural and supra-aural headphones use a band over the top of the head to hold the drivers in place. Another type, known as earbuds or earpieces, consists 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 a headphone and microphone.

<span class="mw-page-title-main">Active noise control</span> Method for reducing unwanted sound

Active noise control (ANC), also known as noise cancellation (NC), or active noise reduction (ANR), is a method for reducing unwanted sound by the addition of a second sound specifically designed to cancel the first. The concept was first developed in the late 1930s; later developmental work that began in the 1950s eventually resulted in commercial airline headsets with the technology becoming available in the late 1980s. The technology is also used in road vehicles, mobile telephones, earbuds, and headphones.

<span class="mw-page-title-main">Hearing aid</span> Electroacoustic device

A hearing aid is a device designed to improve hearing by making sound audible to a person with hearing loss. Hearing aids are classified as medical devices in most countries, and regulated by the respective regulations. Small audio amplifiers such as personal sound amplification products (PSAPs) or other plain sound reinforcing systems cannot be sold as "hearing aids".

<span class="mw-page-title-main">Earplug</span> Device to protect ears from loud noises

An earplug is a device that is inserted in the ear canal to protect the user's ears from loud noises, intrusion of water, foreign bodies, dust or excessive wind. Since they reduce the sound volume, earplugs may prevent hearing loss and tinnitus, in some causes.

<span class="mw-page-title-main">Earmuffs</span> Ear-protecting headgear worn over ears to protect from cold or loud noise

Earmuffs are clothing accessories or personal protective equipment designed to cover a person's ears for hearing protection or warmth. They consist of a thermoplastic or metal head-band that fits over the top or back of the head, and a cushion or cup at each end to cover the ears.

Shure Incorporated is an audio products corporation headquartered in the USA. It was founded by Sidney N. Shure in Chicago, Illinois, in 1925 as a supplier of radio parts kits. The company became a consumer and professional audio-electronics manufacturer of microphones, wireless microphone systems, phonograph cartridges, discussion systems, mixers, and digital signal processing. The company also manufactures listening products, including headphones, high-end earphones, and personal monitor systems.

<span class="mw-page-title-main">Ultimate Ears</span> American audio equipment manufacturer

Ultimate Ears is an American custom in-ear monitor (IEM), speaker, and earphone manufacturer based in Irvine and Newark, California, United States.

<span class="mw-page-title-main">In-ear monitor</span> Audio earpiece commonly used in live music and television

In-ear monitors, or simply IEMs or in-ears, are devices used by musicians, audio engineers and audiophiles to listen to music or to hear a personal mix of vocals and stage instrumentation for live performance or recording studio mixing. They are also used by television presenters to receive vocal instructions, information and breaking news announcements from a producer that only the presenter hears. They are often custom-fitted to an individual's ears to provide comfort and a high level of noise reduction from ambient surroundings. Their origins as a tool in live music performance can be traced back to the mid-1980s.

Acoustic quieting is the process of making machinery quieter by damping vibrations to prevent them from reaching the observer. Machinery vibrates, causing sound waves in air, hydroacoustic waves in water, and mechanical stresses in solid matter. Quieting is achieved by absorbing the vibrational energy or minimizing the source of the vibration. It may also be redirected away from the observer.

A noise-canceling microphone is a microphone that is designed to filter ambient noise.

<span class="mw-page-title-main">Audio headset</span> Telephone or computer accessory

A headset is a combination of headphone and microphone. Headsets connect over a telephone or to a computer, allowing the user to speak and listen while keeping both hands free. They are commonly used in customer service and technical support centers, where employees can converse with customers while typing information into a computer. They are also common among computer gamers and let them talk with each other and hear others while using their keyboards and mice to play the game.

<span class="mw-page-title-main">Apple headphones</span> Lineup of products manufactured by Apple, Inc.

Apple Inc. has produced and sold headphones since 2001, available for standalone purchase and bundled with iPhone and iPod products. Apple's current product line consists of EarPods, AirPods and AirPods Pro, and AirPods Max.

<span class="mw-page-title-main">UE 900</span>

UE 900 and UE 900S are noise-isolating earphones manufactured and marketed by Logitech, under the Ultimate Ears brand. They are aimed at listeners who prefer neutral sound signature. They are rated as one of the best ear phones in its price range by CNET.

<span class="mw-page-title-main">TV Ears</span>

TV Ears is an American, privately held audio technology company that specializes in voice clarifying television products for the hearing impaired. It was founded in April 1998 by George Dennis. They are located in Spring Valley, California, where they house the North American distribution center, support, and sales teams, while employing approximately 50 people. TV Ears serves hearing impaired customers throughout the world, with their predominant markets being in the United States, Canada, and Europe.

<span class="mw-page-title-main">Hearing protection fit-testing</span> Test for determining the effectiveness hearing protection devices

Hearing protector fit-testing measures the degree of noise reduction obtained from an individual wearing a particular hearing protection device (HPD) - for example, an earplug or earmuff. Such measurements are necessary because noise attenuation varies across individuals due to anatomical differences and inadequate training as to the proper wear and use. Labeled HPD attenuation values are average values that cannot predict noise attenuation for an individual; in addition, they are based on laboratory measurements which may overestimate the noise reduction obtained in the real world.

<span class="mw-page-title-main">AirPods Pro</span> Wireless earbuds produced by Apple

AirPods Pro are wireless Bluetooth in-ear headphones designed by Apple, initially introduced on October 30, 2019. They are Apple's mid-range wireless headphones, available alongside the base-level AirPods and the highest-end AirPods Max.

Huawei FreeBuds are wireless Bluetooth and NearLink earbuds. They were first announced and released on March 27, 2018, alongside Huawei P20 series. In addition to playing audio, the Huawei FreeBuds contains a microphone that filters out background noises as well as built-in accelerometers and optical sensors capable to detect taps and pinches and placement within the ear, which enables automatic pausing of audio when they are taken out of the ear.

References

  1. ↑ Molesworth, Brett; Burgess, Marion (2013). "Improving intelligibility at a safety critical point". Safety Science . 51. Elsevier: 11–16. doi:10.1016/j.ssci.2012.06.006.
  2. ↑ Molesworth, Brett; Burgess, Marion; Kwon, Daniel (2013). "The use of noise-cancelling headphones to improve concurrent task performance in a noisy environment". Applied Acoustics. 74. Elsevier: 110–15. doi:10.1016/j.apacoust.2012.06.015.. Recognition and recall of audio information improved when 65 dB(A) background noise was blocked by noise-cancelling headphones, and performance was "no different" when listening with the headphones while at the same time working a mathematical puzzle, than while trying to listen to the same audio with neither puzzle nor headphones.
  3. ↑ Kuo, Sen. M (July 19, 2018). "Development and Evaluation of Light-Weight Active Noise Cancellation Earphones". Applied Sciences. 8 (7): 1178. doi: 10.3390/app8071178 .
  4. ↑ Reinhard Lerch, Gerhard Sessler, Dietrich Wolf: Technische Akustik: Grundlagen und Anwendungen, Kapitel 14.7.3 Kopfhörer – Hörertypen, Verlag Springer (2008), ISBN   9783540234302, Seite 431
  5. ↑ US Grant, US2966549A. "Apparatus for improving intelligence under high ambient noise levels". patents.google.com.{{cite web}}: CS1 maint: numeric names: authors list (link)
  6. ↑ McKinley, L., Richard. "Auditory and Acoustic Research and Development At Air Force Research Laboratory (AFRL)" (PDF). Archived (PDF) from the original on October 16, 2019.
  7. 1 2 How a "Genius" Engineer Designed the First Noise Cancelling Headsets. The Broadcast Bridge. 19 February 2015. Retrieved 2020-12-26.
  8. ↑ Yu, Winnie & Smith, Michael W., MD (November 7, 2013). "Will a Gadget Help You Sleep?". WebMD.{{cite web}}: CS1 maint: multiple names: authors list (link)
  9. ↑ Jonaely, Rosarito (March 5, 2018). "How to get quality sleep at night?". Scalar. University of Southern California.
  10. ↑ Gallacher, Stuart (October 17, 2017). "An experimental model to measure the ability of headphones with active noise control to reduce patient's exposure to noise in an intensive care unit". Intensive Care Med Exp. 5 (1): 47. doi: 10.1186/s40635-017-0162-1 . PMC   5645302 . PMID   29043462.
  11. ↑ Greenfield, Paige (25 June 2011). "Deaf to Danger: The Perils of Earbuds". ABC News. Archived from the original on 14 December 2013. Retrieved 20 June 2013.
  12. ↑ Lichenstein, R; Smith, DC; Ambrose, JL; Moody, LA (October 2012). "Headphone use and pedestrian injury and death in the United States: 2004-2011". Injury Prevention. 18 (5): 287–90. doi:10.1136/injuryprev-2011-040161. PMID   22248915. S2CID   25177965.
  13. ↑ "Headphones as a Driving Distraction" (PDF). The Royal Society for the Prevention of Accidents. Archived (PDF) from the original on 15 September 2017. Retrieved 14 September 2017.
  14. ↑ Noise Cancelling Headphones | Office for Science and Society - McGill University
  15. ↑ Why Do Noise Canceling Headphones Hurt My Ears?
  16. ↑ Noise Cancelling Headphones Pressure on Ears: Why It Happens and What
  17. ↑ Ikuta, Nobuhiko; Iwanaga, Ryoichiro; Tokunaga, Akiko; Nakane, Hideyuki; Tanaka, Koji; Tanaka, Goro (2016-12-01). "Effectiveness of Earmuffs and Noise-cancelling Headphones for Coping with Hyper-reactivity to Auditory Stimuli in Children with Autism Spectrum Disorder: A Preliminary Study". Hong Kong Journal of Occupational Therapy. 28 (1): 24–32. doi:10.1016/j.hkjot.2016.09.001. ISSN   1569-1861. PMC   6091992 . PMID   30186064 – via SAGE Journals.
  18. ↑ Beacham, Frank (August 17, 2016). "The Limits of Noise Cancelling Headphones for Professional Use". The Broadcast Bridge.
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