Beginner Pilot: January 2011

Friday, January 21, 2011

Headset (equipment)

From Wikipedia, the free encyclopedia

A typical example of a telephone headset used for voice chats.

A headset is a headphone combined with a microphone. Headsets provide the equivalent functionality of a telephone handset with hands-free operation. Headsets typically have only one speaker like a telephone, but also come with speakers for both ears.^[1] They have many uses including in call centers and other telephone-intensive jobs and for personal use at the computer to facilitate comfortable simultaneous conversation and typing.

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[edit] Types of headset

Headsets can come in single-earpiece and double-earpiece designs. Single-earpiece headsets are known as monaural headsets. However, double-earpiece headsets may be stereo type (two channels of audio signal, one for each earpiece) or the same audio channel for both ear-pieces.
Professional users may choose to wear monaural headsets because they free up one ear, so they can be more conscious of their work surroundings. Telephone headsets are monaural, even for double-earpiece designs, because telephone offers only single-channel input and output.
For computer or other audio applications, where the sources offer two-channel output, stereo headsets are the norm. Telephone headsets generally use 150-ohm loudspeakers with a narrower frequency range.^[2] Stereo computer headsets, on the other hand, use 32-ohm speakers with a broader frequency range.

[edit] External microphone vs. microtube

The microphone arm of headsets may carry an external microphone or be of the voicetube type. External microphone designs have the microphone housed in the front end of the microphone arm. Voicetube designs are also called internal microphone design, and have the microphone housed near the ear-piece. The sound travels through the tube to the microphone.

[edit] Noise-cancelling microphone vs. omni or directional microphone

Most external microphone designs are either omni-directional or noise-canceling type.
Noise-canceling microphone headsets use a bi-directional microphone as elements. A bi-directional microphone's receptive field has two angles only. Its receptive field is limited to only the front and the direct opposite back of the microphone. This create an "8" shape field, and this design is the best method for picking up sound only from a close proximity of the user, while not picking up most surrounding noises.
Bi-directional microphones work better than uni-directional microphones because uni-directional microphones also pick up some of the sound 90 degrees to the desired angle.^{[citation needed]} Omni-directional microphones pick up the complete 360-degree field, which includes most of the surrounding noises. In some instances, when a higher sensitivity is required for the microphone, or when the sound source is further away from the microphone, an omni-direction microphone is the preferred choice.^{[citation needed]} Almost all voicetube designs use an omni-directional microphone.^{[citation needed]}

[edit] Different styles of headsets

Standard headsets with a headband worn over the head are known as over-the-head headsets. Headsets with headband going over the back of the user's neck are known as backwear-headsets or behind-the-neck headsets. Headsets worn over the ear with a soft ear-hook are known as over-the-ear headsets or earloop headsets. Convertible headsets are designed so that users can change the wearing method by re-assembling various parts.

[edit] Telephone headsets

Telephone headsets connect to a fixed-line telephone system. A telephone headset functions by replacing the handset of a telephone. All telephone headsets come in a standard 4P4C commonly called an RJ-9 connector.

Headset compatibility and pin alignment

Not all telephone headsets are compatible with all telephone models. Because headsets connect to the telephone via the standard handset jack, the pin-alignment of the telephone handset may be different from the default pin-alignment of the telephone headset. To ensure a headset can properly pair with a telephone, telephone adaptors or pin-alignment adaptors are available in the market.^[3] Some of these adaptors also provide mute function and handset/headset switch.

Telephone amplifiers

For older models of telephones, the headset microphone impedance is different from that of the original handset, requiring a telephone amplifier to pair with the telephone headset. A telephone amplifier provides basic pin-alignment similar to a telephone headset adaptor, but it also offers sound amplification for the microphone as well as the loudspeakers. Most models of telephone amplifiers offer volume control for loudspeaker as well as microphone, mute function and headset/handset switching. Telephone amplifiers are powered through batteries or AC adapters.

Quick disconnecting cable

Most telephone headsets have a Quick Disconnect (QD) cable, allowing for fast and easy disconnection of the headset from the telephone. This allows the user to disconnect from the telephone, without having to physically remove the headset.

[edit] Computer headset

Front view of Steel series Siberia Neckband gaming headset. The microphone is on the left earcup. With standard 3.5 mm TRS connectors

Computer headsets generally come in two connecting types, standard 3.5 mm & USB connection. General 3.5 mm computer headset comes with two 3.5 mm connectors, one connecting to microphone jack (line-in) and one connecting to speaker jack (line-out) of the computer. 3.5 mm Computer Headsets connect to the computer via a soundcard - which converts the digital signal of the computer to analog signal for the headset. USB computer headset connects to the computer via USB ports, and the audio conversion occurs in the headset or in the control unit of the headset.

[edit] Mobile phone headsets

Mobile (Cellular) Phone Headsets are most often referred to as Mobile Handsfree. Most mobile phones come with their own handsfree in the form of a single earphone with a microphone module connected in the cable. For music-playing mobile phones, manufacturers will bundle stereo earphones with a microphone. There are brands which offer mobile headset outside of the mobile phones developer. The main reason for this is either for better sound quality or higher convenience in the form of wireless solutions.
High quality mobile headsets come a range of wearing-styles, including behind-the-neck, over-the-head, over-the-ear, and lightweight earbuds. Some aftermarket mobile headsets come in a standard 2.5 mm plug, so users have to purchase an additional adaptor for their mobile phones; a USB headset for a computer also cannot be directly plugged into a phone's or portable media player's micro-USB slot. Smartphones often use a standard 3.5 mm jack, so users may be able to directly connect the headset to it.
As for Wireless Mobile Headsets, many of them now use Bluetooth technology, as a growing number of mobile phones come with a Bluetooth transceiver, and a Bluetooth transceiver may be plugged into a computer's USB port. Bluetooth versions 1.1 and up (all non-deprecated versions) can transmit voice-calls and many popular music and video formats, but audio will not be played in stereo unless the cellphone or media device, and the headset, both have the A2DP profile.

[edit] Wireless headsets

Wireless headsets are quickly becoming a new trend for both business and consumer communications. There are a number of solutions for wireless, and they usually differ according to application and power-management.

[edit] DECT wireless headsets

A typical Wireless DECT headset by Accutone.

Digital Enhanced Cordless Telecommunications (DECT) is one the most common standards for cordless telephones. It uses 1.88 to 1.90 GHz RF (European Version) or 1.92 to 1.93 GHz RF (US Version). Different countries have regulations for the bandwidth used in DECT, but most have pre-set this band for wireless audio transmission. The most common profile of DECT is Generic access profile (GAP), which is used to ensure common communication between base station and its cordless handset. This common platform allows communication between the two devices even if they are from different manufacturers. For example, a Panasonic DECT base-station theoretically can connect to a Siemens DECT Handset. Based on this profile, developers such as Plantronics, Jabra or Accutone have launched wireless headsets which can directly pair with any GAP-enabled DECT telephones. So users with a DECT Wireless Headset can pair it with their home DECT phones and enjoy wireless communication.

[edit] 2.4 GHz wireless headsets

Because DECT specifications are different between countries, developers who use the same product across different countries have launched wireless headsets which use 2.4GHz RF as opposed to the 1.89 or 1.9 GHz in DECT. Almost all countries in the world have the 2.4 GHz band open for wireless communications, so headsets using this RF band is sellable in most markets. However, the 2.4 GHz frequency is also the base frequency for many wireless data transmission, i.e. Wireless LAN, Wi-Fi, Bluetooth..., the bandwidth may be quite crowded, so using this technology may be more prone to interference.
Because 2.4 GHz Wireless Headsets cannot directly "talk" to any standard cordless telephones, an extra base-unit is required for this product to function. Most 2.4 GHz Wireless Headsets come in two units, a wireless headset and a wireless base-station, which connects to your original telephone unit via the handset jack. The wireless headset communicates with the base-station via 2.4 GHz RF, and the voice signals are sent or received via the base unit to the telephone unit. Some solutions will also offer an automatic handset lifter, so the user can wirelessly lift the handset off the telephone by pressing the button on the wireless headset.

[edit] Bluetooth wireless headsets

This section may require cleanup to meet Wikipedia's quality standards. Please improve this section if you can. The talk page may contain suggestions. (September 2008)

A typical Bluetooth headset.

Most users have heard about Bluetooth, and although this technology was designed originally for a much wider application, it has today become largely for voice transmission (a notable exception to this would be the use of Bluetooth in wireless controllers of latest generation gaming consoles, like the Wiimote and the DualShock 3). The reason for this general exclusivity is because of the power/range settings of Bluetooth. Bluetooth uses 2.4 GHz RF, similar to WLAN or Wi-Fi; however, by default it is set for a very close proximity usage for power consumption benefits. This deficiency for a longer-range coverage made bluetooth technology un-desirable for data transmission. As nowadays more and more mobile phones come equipped with bluetooth, this technology has become a common wireless profile for wireless mobile phone headsets only.

A stereo Bluetooth headset.

When choosing a Bluetooth headset users should be aware that bluetooth headsets come in different types as well. Standard bluetooth headset's using version 1.0 or 1.1 are often a single-side monaural earpiece, which can only access the Headset/handsfree profile of Bluetooth. Depending on the phone's operating system, this type of headset will either play music at a very low quality (because the phone is converting it into a voice signal) or will be unable to play music at all (because the phone cannot perform such a conversion). Users who need a stereo-music playing Bluetooth headset should look for a headset with the A2DP profile.^[4] Users should note that some A2DP-equipped headsets will automatically de-activate the microphone function during music-listening, so if these headsets are paired to a computer via bluetooth connection, the headset may either disable the stereo function or the microphone function.

[edit] Bluetooth wireless desktop solutions

Some developers have offered complete desktop solutions using Bluetooth technology. With a base-station that connects via cables to the fixed-line telephone and also the computer via soundcard, users with any bluetooth headset can pair their headset to the base-station, hence enabling them to use a single headset for both fixed-line telephone and computer VoIP communication. This type of solution, when used together with a multiple-point bluetooth headset enables user to use a single bluetooth headset to communicate in Telephone/Computer/Mobile.
There are now Bluetooth office headsets that incorporate Class 1 Bluetooth into the base station so that when using with a Class 1 Bluetooth headset, the user can get a greater distance from the phone or computer; generally around 100 feet compared to the 33 feet of Class 2 Bluetooth, which is what most Bluetooth headsets run on. The headsets that come with these base stations connect to cell phones via Class 2 Bluetooth, so you still get the same 33 foot range from your cell phone.