### device:

Harp
* Some harps have a great, loud voice and ego, and are easily heard.
* are a very unique instruments
  - big instruments to pack
  - chordophones
  - lagers
  - located in concert halls
  - predatory, feeding mostly on crustaceans such as crabs
  - solids
  - stringed instruments
  - support
* are used for angels
  - melody
  - playing
  - relaxation
* use open strings exclusively, thus the range of each is determined by the number of strings.

Headlamp
* Some headlamps are part of ambulances
  - automobiles
  - cars
  - go-karts
  - motorbikes
  - taxis
* includes sections.
* is light

### device:

Headphone
* are a dream to wear
  - as individual as loudspeakers
  - audio devices
  - available to people sharing a household for private listening
  - black with silver ear pieces
  - generally low-impedance devices
  - requried for personal stereos
* are to be used at all times when listening to music or sound on the computers
  - for sound output
  - useful for private listening in public areas
* can also enhance learning.
* cause hearing loss.
* come in many different sizes from big to small.
* have individual volume controls to adjust for hearing differences.
* minimize noise from the sound accompanying software programs.
* often increase the attention to the stimuli and it is possible to separate the channels.
  * ' are electronic audio devices that people wear over their ears. They let people listen to music on a walkman, MP3 player or computer. Headphones come in many different sizes from big to small. They are also known as 'earphones, earbuds, stereophones, headsets' or even 'cans'.
* use a nine volt battery.
* work best for people who can sleep comfortably on their backs without turning much.

### device:

Heat exchanger
* are balanced systems, and exhaust the same amount of air as they bring in
  - manufactured with various flow arrangements and in different designs
  - some of the essential items within refineries and chemical plants
* can also have a large amount of flexure if there are enough tubes.
* cool the refrigerants through a series of phase separations.
* help cool the water in the pool.
* is the compartment that house the water as it flows through the unit.
* keep the gases at low enough temperatures to be separated.
* recover most of the energy used to warm the water.
* transfer the heat from the fluid to the water stored in the tanks.
* work both directions, effectively reducing both heating and cooling loads.

### device:

Heater
* Most heaters burn clean fuel
  - consume energy
* Most heaters contain oxygen depletion sensors
* Most heaters convert chemical energy
  - have thermostats
  - use electricity
* Some heaters combine radiant and fan-forced convective systems
  - the effects of radiant and convection heating
  - contain plastic
* are capable of lower temperature
  - warm foots
* are located in automobiles
  - dwellings
  - garages
  - homes
  - houses
  - offices
  - public buildings
  - part of automobiles
* are used for comfort
* have functions
* includes sections.
* operate on inside or outside combustion air.
* produce carbon monoxide and other dangerous gases.
* provide warmth.
* serve purposes.
* supply the warmth some sea anemones require, but they can burn themselves on contact.

### device | heater:

Convection heater
* have small fans that circulate the warm throughout a room.
* warm the air and are best at heating enclosed, relatively draft-free spaces.
* work by filling a room with warm air.

Convective heater
* circulate warm air upward and outward in all directions.
* heat the air, which then heats the environment.

Deicer
* Most deicers dry to a white powdery residue.
* Some deicers corrode metal, causing damage to cars and aluminum siding.
* melt down through the ice or snow to the hard surface, then spread out underneath.
* work best when used in combination with scraping and shoveling.