Headphones or earphones are fast becoming an indispensable device for all those who have one or other electronic devices from media players to phones, from computers to palmtops. People who use it regularly often tend to use it for long durations. There could be temporary or even permanent hearing impairment if the headphones are used at high volume. Often the listener increases the volume to drown outside noise in such places as aircraft, subways, large crowds or in traffic. The normal pain associated with higher levels of volume disappears. Longer periods of higher levels of volume could damage the ear. It is estimated that only about 5 percent stands such risks. Though there has been suggestions or limiting the volume of provide some form of warning has not gone well with listeners. Such safety precautions have not been introduced in the products in the market.

In-ear headphones and canalphones pose lesser risk of hearing impairment. The volume need not be increased to drown external noise as the external noise itself is blocked by the noise isolation properties of the on-ear seal. In some countries, there are restrictions to using the headphones while driving vehicles including using earphones in one ear. The drivers face the risk of not hearing external noise such as car horn losing the awareness of the situation which can cause accidents. There are other activities that should either keep away from using of headphones or keep it at a low volume.

A number of companies manufacture headphones for DJs, professionals and Call Centers. There come in many models, styles and designs. The more reputed companies manufacturing headphones include AKG, Sennheiser, Grado, Bose and Sony. Sennheiser produces wired and wireless headphones as well as in-ear, mini and high definition headphones. The wired headphones manufactured by this company for instance include Sennheiser CX300 earbuds, Sennheiser CX6, Sennheiser CX 500, Sennheiser CX 400, Sennheiser HD800, Sennheiser HD650, Sennheiser RS120 and Sennheiser PX 100. Details of all these products are found in the Internet. It is also possible to buy online.

Headphones were first introduced by Sony with their Walkmans. Headphones have become commonly used with a variety of devices such as radio, Discmans, CD player, audio amplifier, portable DVD players, Computers, DAT recorders, home theater, mobile phone, MP3s, iPhones and iPods.

The first hand held computer to be launched was by Casio with its Casio PF-3000 in 1983. It was a simple digital diary. The first pocket computer to be developed was by Psion in United Kingdom in 1984. Psion Organiser I had a flat-file data base, clock and calculator. It had no operating system. This marked the beginning of the emergence of an altogether new and exciting range of hand held computers called as Personal Digital Assistants, palm tops or palm pilots. Companies such as Apple and Palm Computing were amongst the first one to join in with their own versions of handheld computers. The most well know PDA was the Palm Pilot which was launched towards the end of 1990s. In 1996, Nokia introduced the first mobile phone with PDA functionality. This was called 9000 Communicator and became a top selling PDA in the world. A new category of phones emerged, the smartphones, such as the RIM Blackberry, Nokia N-Series and Apple iPhone.

Portable gadgets have rapidly taken over from electronic devices which today look pretty clumsy and bulky. The process of miniaturization has simply shrunk them, from what sat impressively on the table, to something that you can hold in your palm. There used to be a number of devices on the table top that one had to make use for different functions whether it is audio, video, Internet, telephony and many more. Most of these were not portable also. But with the rapid advancement of technological convergence, most of these devises have become combined into one and that too into a hand held device. The portable devices include Ultra Mobile PC, portable audio player, netbooks, portable media player, portable digital assistant and smartphone.

There are a numerous PDAs in the market providing a variety of features. These include Palm Z22, Pharos 535e Traveler, PalmOne M515 Color Handheld , HP iPAQ 111 Classic Handheld, Palm TX Handheld, Palm Tungsten E2 Handheld, Nokia N810 Portable Internet Tablet and many more.

With wireless Internet access or WiFi, it has become even more convenient to not only download music and video, check E-mail, carry out web transactions including mobile banking and online purchases but many more. These portable devices combine entertainment, learning, work and play.

iPAQ is a pocket personal computer as well as a personal digital assistant (PDA) which was introduced by Compaq in 1999. Hewlett Packard acquired Compaq and is now marketed under the HP brand. It is a combination of mobile phone, PDA, palm top computer and smart phone. It also has GPS facility, a card reader, wireless networking and Bluetooth interface. It has the advantage of having multimedia capabilities using with Microsoft Windows interface.

There are very many applications in PDAs. The user can actually decide what kind of applications are to be incorporated. PDAs have applications that are useful in medicine. It assists in diagnosis of disease, treatment and the selection of drugs. It can record symptoms as well as present information on treatments. PDAs are applied in the educational field, particularly by students. The relevant tasks that it can execute are digital note taking and its modification, the spell-check, dictionaries, e-books storage and use, digital planning lessons, word processing and many others. It finds application in the field of sports in the calculation of speed, distance and time; pre-flight planning and assistance to the glider pilots in navigation linked to the use of GPS, and for road rallyist with GPS assisted navigation.

Originally developed by Digital Equipment Corporation Western Research Laboratory (WRL), iPaq runs on an Intel Celeron processor or an Intel Pentium III processor with 500 MHz to 1 GHz processing speed. Its memory ranges from 128 MB to 512 MB which can be upgraded. Some of the top handheld PDA gadgets are HP iPAQ 111 Classic Handheld, Palm TX Handheld, Palm Tungsten E2 Handheld, Nokia N810 Portable Internet Tablet, HP iPAQ Handheld, Asus A626 3.5-inch PDA Windows Mobile 6.0, Nokia 02700T6 N810 WiMAX Edition Portable Internet Tablet, and Sony Ericsson C905i Unlocked Cell Phone.

The ways mobile technologies have developed have impacted lifestyles in both work and play. Mobile shopping and mobile banking has become convenient both in terms of saving time and energy. Web surfing for as varied purposes as knowing the sports score, and getting weather reports and stock quotes using PDAs is becoming common. In fact, PDA is becoming an indispensable gadget for our activities and functioning.

A personal digital assistant (PDA) is also known as a palmtop computer. It is a handheld computer. Newer PDAs have color screens and audio capabilities. This makes it possible for it to be used as portable media players, smartphones or mobile phones, or web browsers. Internet, extranets or intranets can be accessed by many PDAs now using Wireless Wide-Area Networks or Wi-Fi. PDAs have been introduced with Touch Screen technologies.

The first PDA to be launched was the CASIO PF-3000 in 1983. Nokia introduced the PDA functionality for the first time into mobile phone in 1996. This was called 9000 Communicator and became the world’s best selling PDA. Smartphones, a category of phones, emerged for instance the Nokia N-Series, RIM Blackberry and Apple iPhone. The present PDA has a memory card slot for storing data and the touch screen. Bluetooth, IrDA or WiFi provide the connectivity. The softkeys, directional pad and a numeric keyboard or thumb keyboard for input continue to be used with those PDAs that do not have the touch screen facility. The software programs normally included are appointment calendar, a to-do list, a note program and an address book. The PDAs that have connectivity have E-mail and web support. Information can be stored in PDAs and can be accessed by the user when needed. Realtime automobile navigation is offered by PDAs that are fitted with differential Global Positioning System (GPS) receivers. Such PDAs are available in some of the new cars. Road conditions, roadside mobile radar guns, traffic conditions and dynamic routing are displayed by many PDAs.

Some well known PDAs are E-TEN, Acer N Series, Abacus PDA Watch, Audiovox (Sprint) PPC Series, AlphaSmart, Encore Simputer, Amida Simputer, Fujitsu Siemens Loox, BlackBerry, I-mate, HP iPAQ, Dell Axim X51, Nokia E Series, MotoRokr E8, Motorola Rokr E6, Apple Inc.’s iPhone & iPod Touch and SonyEricsson P-series. Further details can be had, for instance, for Dell Axim X51 from Dell Axim X51 review

PDAs are also used for mobile data applications by businesses and government organizations. Applications include package delivery, supply chain management in warehouses, medical treatment and record keeping in hospitals, route accounting, parking enforcement, facilities maintenance and management, capital asset maintenance, access control and security, ‘wireless waitress’ applications in restaurants and hospitality venues, and meter reading by utilities. Data capture devices such as Bar Code, Smart Card Readers and RFID were also incorporated into many of these PDAs. 77