Frequently Asked Questions about Listen Products
Frequently Asked Questions about Listen Products
What are the transmission ranges of Listen products?
LT-800
Stationary Transmitter:
500 to 1,500 feet at 72MHz
1,000 to 3,000 feet at 216MHz
LT-700
Portable Transmitter:
100 to 150 feet at 72MHz
100 to 150 feet at 216MHz
You
can expect Listen products to broadcast in the range of 100 feet to 3,000 feet
depending on your application and the products you're using. Listen receivers
use the most advanced RF technology that delivers excellent RF sensitivity and
interference rejection. This translates to longer transmission range. Listen's LT-800
Stationary Transmitter along with Listen's
LA-122 Universal Antenna Kit will provide excellent results. Locate the
antenna at the highest possible location within the facility so receivers have
an unobstructed line of sight to the antenna. The Listen LT-700
Portable Transmitter has less output power to both restrict signal coverage
(to reduce interference with other portable transmitters) and to conserve
battery life. It should be noted that the LT-700 Portable transmitter uses the
microphone cable as its transmission antenna and thus Transmission range is
affected by the position of this cable. To achieve the longest signal coverage
you would use a Listen LT-800 Stationary Transmitter at 216MHz and a Ground
Plane Antenna (LA-107). This is perfect for large venues such as stadiums,
auditoriums, arenas, concert halls and racetracks.
What
type of coax is used with Listen products and how far can I remote the antenna?
Listen
antennas use 50 ohm coaxial cable. For cable runs under 100 ft (30.5m) at 72MHz
or 50 ft (156m) at 216MHz, you can use RG58 coax. For longer cable runs, Listen advises using RG8
coax with a minimal number connectors. Below are the approximate signal
loss for Listen LA-122 RG58 Coaxial Cable:
72MHz
- 1-2 dB per 100 feet (30.5m)
216MHz - 3-5 dB per 100 feet (30.5m)
What
type of connector is used between the LT-800 and the coaxial cable to its remote
antenna?
Effective March 1, 2002, all Listen remote antennas are shipped with standard BNC connectors.
The
LT-800-072 Transmitter auxiliary antenna connection will remain a reverse BNC
connector. This satisfies the FCC rule that part 15 auditory assistance
transmitters have non-standard RF connections. Listen provides the adaptor to
convert the LT-800-072 auxiliary antenna connection to standard BNC.
The
LT-800-216 Transmitter auxiliary antenna connection has been changed to a
standard BNC connector. This change facilities the use of the above noted 216MHz
antennas with standard BNC's. The LA-121 is not necessary when using the
LT-800-216 or associated antennas.
To
be FCC compliant, you must use a Listen supplied antenna. It is not necessary to
retrofit existing systems.
What
is the output power of Listen stationary transmitters?
Listen
stationary transmitters operate at the highest possible output power allowed by
the FCC. At 72MHz, the LT-800 delivers 80,000 microvolts at 3 meters, and at
216MHz, it delivers 100 milliwatts of power to the antenna.
How
do I connect my Listen System up to my Sound System?
For the LT-800, connect your audio source(s) to one or both audio input connections (see below). The LT-800 Input 1 offers a choice of balanced XLR or 1/4 inch phono connection. Input 2 is an unbalanced phono connector. You have the option of sending the LT-800 transmitter a variety of signal outputs including line, microphone and speaker level.
The LT-700 can receive mic and line level audio sources (not speaker level).
These audio sources can be an output from your existing mixing console, a microphone, or other audio source. Which is best depends upon your application. If you are uncertain please call us at (440) 786-1287 or (800) 388-3044.
Can Listen receivers interface to hearing aids?
Yes. This is accomplished by using Neckloop (LA-166) supplied by Listen or a direct audio interface (DAI). The LA-166 is a personal inductive loop is connected to a Listen receiver and then is placed around the neck. An inductive loop generates a magnetic field that is picked up by a hearing aid that is equipped with a "T" coil. All such hearing aids have a switch with positions marked O, T, and M or O, T, MT, and M. The MT, if your hearing aid has one, indicates that in this position, both the "T" coil and the microphone are active.
You
can also interface your Listen receiver with silhouettes, and an adjustable
cochlear patch cord can be used to interface with cochlear implants. Call us for more information on the direct audio interface options.
What
applications can I use Listen products for?
The
FCC permits use of the 72MHz and 216MHZ frequency bands for assistive listening.
These frequency bands were specifically set aside to help people who are hard of
hearing. Thus, both of these bands can be used in houses of worship, schools,
cinemas, theatres, arenas, stadiums, concert halls, racetracks, amusement parks,
funeral homes, etc. Any public place accessible to someone hard of hearing may
use both of these frequency bands. In fact, the ADA requires by law many of
these places to have such devices.
Listen
products are specifically designed for auditory assistance, but can be used for
sound field reinforcement and remote amplification when used in addition to
applications regarding the hearing impaired.
The
FCC has expanded the applications for the 216MHz band to include: Tour groups
and factory tours, Language translation, Medical/Dental, and Law Enforcement.
The 72MHz band should not be used for these applications.
Why would I want to use the 216MHz frequency range?
The
216MHz frequency band offers roughly twice as much transmission range and may be
less prone to interference in your application. Thus, in applications such as
stadiums and racetracks, Listen products in the 216MHz frequency band can
deliver a significantly longer transmission range. In applications where a large
number of simultaneous transmissions are required (such as language
interpretation or school applications), 72MHz offers more simultaneous channels.
It may be advantageous to use both the 72MHz and 216MHz frequency bands to
achieve the highest number of RF signals in one area.
When
should I use 72MHz and when should I use 216MHz?
Choose a Listen 72MHz system:
* For shorter range application requirements up to 1,500 feet
* For exceptional sound quality
* For compatibility with existing FM assistive listening equipment
Choose a Listen 216MHz system:
* For longer range application requirements up to 3,000 feet
* For areas where interference is a problem
* For good sound quality
* For expanded applications including language interpretation, tour group communications, medical/dental, and law enforcement
What's
the difference between wide and narrow bands and when should I use them?
The
advantage of narrow band channels is that they take up less RF spectrum and thus
more channels can be used in a given area. The disadvantage of narrow band
channels is that they have more noise and the frequency response is not as good
compared to wide band channels. Here's a rule of thumb: use narrow band channels
when you're trying to get as many channels into a given area (such as schools)
to minimize interference, and use wide band channels everywhere else.
Is
Listen compatible with other FM wireless listening systems?
Listen
products have been designed for 100% compatibility with all major manufacturers
of assistive listening systems. Listen products both receive and transmit (in
both wide and narrow band) on ALL the same channels as the following
manufacturers: Comtek, Drake, Gentner, Phonic Ear, Telex and Williams Sound.
Are
Listen Accessories
compatible with other FM wireless products?
Listen uses standard 3.5mm cable connectors for our microphones and earphones, and our microphones require 3VDC phantom power. All our remote antennas use standard BNC connectors, and coaxial cabling.
The
LT-800-072 Stationary Transmitter
(72Mhz) has a reverse BNC connector, and the LT-800-216 Stationary Transmitter
has a standard BNC (the United States Federal Communications Commission requires
72MHz transmitters have a "non-standard" antenna connection).
Any product made by another manufacturer with these specifications can be utilized with Listen accessories.
Most
other manufacturers do not offer drop in charging, so the Listen charging cases
will not work with other products. Carrying and storage cases, however, will
accept anything that meets their physical limitations.
Do I have to use Listen batteries with my Listen portable products?
Yes
and No. Listen uses standard AA batteries. However, meters and specifications
are calibrated up for Listen High
Capacity AA Batteries, so results may very if you use other products.
Also,
Listen's SmartCharging is calibrated for Listen's NiMH
Rechargable AA Batteries. Other rechargable batteries should not be used as
results will vary and may invalidate your warranty.
How
many Listen transmitters can be used together in one area or room?
72MHz
- 2 to 8 channels
216MHz - 2 to 4 channels
How do I select these multiple channels to be used with full compatibility?
For
this, you'll need to choose your transmitting frequencies carefully. The
following guidelines should be used to choose channels-
Can I use more than 6 channels in one area but in different rooms?
Yes.
There are three levels of adjustable RF output on the LT-800; this combined with
separate transmitter positions can facilitate transmitting on many more
simultaneous channels. Utilizing a receiver with adjustable squelch makes this
process even easier.
How many receivers can be used with each transmitter?
Listen's
transmitter broadcasts a radio signal into a given area. ANY receiver in that
area can receive that signal. Thus, any number of receivers can be used,
including unlimited numbers of LR-300,
LR-400,
LR-500
portable receivers, LR-600
Wireless Speaker/Receivers and/or LR-100
Stationary Receiver / Power Amplifiers.
What types of auditory assistance systems are there?
FM
(Radio Systems), Infrared, and Audio Induction Loop are the three basic
alternatives for assistive listening.
FM systems, such as Listen's systems, transmit sounds as radio waves within a specially FCC-designated range. The user must access the transmission through a receiver. In general, FM systems are less expensive than their alternatives. They also are the easiest and more flexible to install. Their radio waves will pass through walls and in Listen's case, reach up to 3,000 feet. Caution needs to be taken when using FM systems to prevent interference. Listen products have three solutions to prevent interference: One, users will most likely find (out of 57 channels on each Listen receiver and transmitter, including ~40 short-range narrow bands) a clear transmission channel that will not interfere with other broadcasts. Two, Listen products offer the ability to adjust RF gain on the stationary transmitter in order to decrease transmission range. And three, excellent frequency sensitivity and selectability are built in to Listen products, thus, greater distance and less interference.
An alternative use of FM systems is sound field. Sound fields uses FM transmissions, however, audio is delivered through speakers in the room or venue.
Infrared
transmission is a common form of assistive listening. Infrared converts an audio
signal to invisible light waves that are picked up by special receivers that
change the signal back to audio. The advantage to infrared is that its light
signal is blocked by walls. This may provide confidentiality and eliminate any
interference to neighboring programs. Disadvantages include: walls and objects
block the light signal (!), and infrared is light sensitive and cannot be used
outdoors or in well-lit environments.
Audio
Induction Loop
is the third, less
common technology. It transmits, from a wire surrounding the intended audience,
modulated electromagnetic signals that can be picked up whether by one's
personal hearing aid telecoil or by a pocket size induction receiver. The user
must sit within the surrounding wire. An audio loop is expensive to install in
large venues, but is fairly economical for small areas. It is subject to
interference from fluorescent light transformers and high-voltage lines.
Why
use FM auditory assistance devices versus infrared?
Infrared
systems use infrared light to transmit the audio signal. When this light is
blocked, the signal stops. Thus, infrared systems are susceptible to people and
objects getting in the way. And, infrared systems do not work in sunlight.
Another problem with infrared systems is the cost, complexity and unsightliness
of installing emitter panels. Infrared systems offer the advantage of security
(you can only hear the audio when infrared light is detected by the receiver)
and simplicity of receivers (one receiver is used and it does not have to be
tuned). FM systems can transmit through objects and operate as effectively in
sunlight as they do indoors. FM systems are much easier to install and they cost
much less.
What is sound field and does Listen offer sound field solutions?
In
school or training applications the instructor wears a portable transmitter with
a microphone. The instructor's voice is transmitted to a speaker that is located
near the students. This creates a "sound field" so the students can
hear better. Studies have shown that 25% of all students (even those who are not
hard of hearing) could have an improved learning experience with a sound field
system. Listen products can easily be used to create a sound field system. In
this case, an LT-700 is used
as the portable transmitter and an LR-600
Wireless Speaker/Receiver or an LR-100
Stationary Receiver / Power Amplifier is used to distribute the audio.
Because Listen products are compatible with all major manufacturers, you'll
never have to been concerned about obsolescence of existing systems.
Why would I use a sound system instead of a personal FM assistive listening system?
Some
students are self-conscience about wearing an assistive listening receiver. In
addition, the receiver increases the chance of the receiver being lost or
damaged by the student. A sound field system eliminates these issues. In
addition, a larger number of students are helped by a sound field system instead
of just the students using personal receivers.
Can Listen products be used for two-way communication?
The
FCC specifically mandates that assistive listening products cannot be used for
two-way communication.
Do Listen products have government certifications?
Listen
products are approved per product type in the United States and Canada. Listen
transmitters are type accepted by the FCC. Listen power supplies are UL
approved. For certification specifications, please contact us. Listen products are manufactured to the highest quality
standards in an ISO 9001 facility.
What is the warranty on Listen products?
Listen products offer a lifetime limited warranty protecting you from manufacturing material and workmanship defects. When you do have a problem, expect your problem to be resolved quickly and conveniently. Simply contact us so technical problems can be resolved or a Return Authorization can be issued (please note, products must be returned with a Return Authorization Number for the warranty to be effective).
Some
ALD products on the market are less expensive than Listen's products; why would
I choose Listen?
Listen
products may cost more initially, but in the long term they are the most cost
effective. There are three reasons for this:
·
SQ!:
Listen products currently offer the best sound
quality in the business - 80dB SNR!
·
Frequency Agility:
Because Listen products offer 57 wide and narrow band channels they are 100%
compatible with existing product (thus there is never a need to obsolete
existing systems) and, with 57 channels it is almost always possible to find a
clear channel. Channels are tunable on-site by simply pressing the UP or DOWN
channel buttons.
·
SmartChargeTM
battery technology can recover the
cost of receivers in less than two years by eliminating the need to replace
alkaline batteries and an expensive external battery charger is not needed.
· Listen's
lifetime warranty, what-ever-it-takes performance guarantee, and Try
Before You Buy 30-day Demo Program takes the complication and risk out
of choosing an FM assistive listening system.
· More Features & Accessories: Listen products offer many user-friendly features and a full line of accessories. Listen charging cases feature automatic drop in charging with a secure place for earphones to prevent cable tangling. Simple, easy storage, handling and charging of your Listen system saves money and eliminates hassle.