Topics: Nelson Mandela, South Africa, African National Congress Pages: 6 (2162 words) Published: February 7, 2014
Loudspeakers use both electric and mechanical principles to convert an electrical signal from a radio, television set or electric musical instrument into sound. For a loudspeaker to produce sound, the signal from the radio, television set, or electric musical instrument needs to be connected to an electronic amplifier. Loudspeakers are usually built by using stiff paper cone, a coil of thin copper wire, and a circular magnet. The cone, copper wire, and magnet are usually mounted in a rectangle-shaped wood cabinet. The coil of copper wire moves back and forth when an electrical signal is passed through it. The coil of copper wire and the magnet cause the rigid paper cone to vibrate and reproduce sounds.

loudspeaker (or "speaker", or in the early days of radio "loud-speaker") is an electroacoustic transducer that produces sound in response to an electrical audio signalinput. In other words, speakers convert electrical signals into audible signals. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful. The most popular speaker used today is the dynamic speaker. The dynamic speaker operates on the same basic principle as a dynamic microphone. When an ac current (i.e., electrical audio signal input) is applied through the voice coil that surrounds a magnet (or that is surrounded by a permanent magnet), the coil is forced back and forth due to Faraday’s law, which causes the paper cone attached to the coil to respond with a back-and-forth motion that creates sound waves. Where high fidelity reproduction of sound is required, multiple loudspeakers may be used, each reproducing a part of the audible frequency range. Miniature loudspeakers are found in devices such as radio and TV receivers, and many forms of music players. Larger loudspeaker systems are used for music, sound reinforcement in theatres and concerts, and in public address systems. •

Essentially, hearing aids are electronic devices that pick up sound waves with microphones, which then process that sound through an amplifier, then send the processed sound into the eardrum with a speaker (receiver).

The simplicity and complexity with which this is achieved depends on the type of instrument that is used.

For instance, the newest, digital hearing aids contain very sophisticated and powerful processors and are able to sample the sound environment, manipulate the wanted and unwanted sounds all in times measured in milliseconds. The end result is clearer sound, with minimal distortion.

Simpler hearing aids, while still effective, do not process sound as effectively as digital instruments.

It’s important to note that hearing improvement with any instrument depends on the type and degree of hearing loss, proper diagnostic testing and the fitting of the hearing aid. No hearing aid can restore normal hearing and not everyone benefits equally, but they can provide a significant improvement to those who have sustained hearing loss.

Hearing aids come in five main types:

1.Behind-The-Ear (BTE) – This hearing device is housed in a curved shell that sits behind each ear and delivers sound through a clear tube normally via a custom made earmould.

2.In-The-Ear (ITE) – Easy to operate, even for users with poor dexterity, ITE devices are housed in a custom-made shell that fits comfortably inside each ear

3.In-The-Canal (ITC) – Barely visible, ITC devices are housed in a custom-made shell that fits comfortably in each ear canal, delivering sound directly to the ear. Though small, ITC devices are easy to operate, even for users with poor dexterity.

4.Completely-In-Canal (CIC) – Fitted inside each ear canal, CIC devices are all but invisible from the outside. These miniature instruments are both powerful and cosmetically appealing, but due to their small size they may sacrifice some features such as...
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