Comparing infrared (IR) and radio frequency (RF) technologies can be as subjective as comparing chocolate and vanilla. It often comes down to a matter of preference. As the radio spectrum becomes increasingly impacted, here are some key benefits of infrared you should consider.
Radio waves can
pass through walls.
cannot pass through walls.
The most common comparison between IR and RF is their physical characteristic. Infrared is transmitted via light, and therefore requires line-of-sight between the transmitter and receiver. This is not difficult to accomplish in a standard classroom (about 30′ W x 30′ L x 10′ H). A reliable IR system can function over 60 feet, which is enough to maintain a good connection even if there is no direct line of sight. Unlike Radio Frequency (RF), IR technology does not pass through solid walls, so conversations stay contained to the room. Because no pairing is required between the transmitter and receiver, the system works instantly after installation.
Or should we say no latency? Because infrared is light, it travels at that speed. Radio Frequency products can have high enough latency (delay) for the listener to see the teacher’s lips moving ahead of the sound arriving at the listener’s ears. You have probably experienced a more extreme version of this problem when streaming a program on your TV. Although classroom audio systems won’t be as bad as your home TV, Infrared alleviates this concern.
The purpose of a microphone is to reproduce the human voice. IR can carry the entire range of human speech 125-8,000 Hz, whereas the most common RF-based teacher microphones have a range closer to 200-7,000 Hz. This lack of fidelity, or definition, creates a “tinnie” sound that is less intelligible than the person’s natural voice.
Why fidelity matters: Unvoiced consonants (f, s, t etc.) lie in the frequency range 2– 8 kHz. For students to understand speech clearly, they must have good hearing across the entire range of frequencies from 125 – 8 kHz. Most radio systems have a max of 7 kHz.
Not only do IR microphones overcome the physical barriers to listening in a classroom, they:
- enable a teacher to use the same microphone in every room,
- prevent the need for sharing between teachers, and
- simplify the deployment of microphones for the entire school.
Summary of Benefits
|Benefits of IR||Why it Matters|
|High Fidelity: Infrared systems can transmit/receive a full range of sound frequencies (frequency response), enabling a more accurate reproduction of audio sources like a person’s voice.||Why fidelity matters: Unvoiced consonants (f, s, t etc.) lie in the frequency range 2– 8 kHz. For students to understand speech clearly, they must have good hearing across the entire range of frequencies from 125 – 8 kHz. Most radio systems have a max of 7 kHz.|
|Low Latency: Latency is the delay before the transmission of sound. Because IR is light based, the transmission of the teacher’s voice from the microphone to the sensor is much faster than radio waves.||Why latency matters: If you have ever watched a video and noticed the person’s speech doesn’t match their lips, then you can imagine what happens if the teacher’s voice doesn’t their lips. Even a slight delay can affect comprehension. Most radio systems have ~17 ms latency whereas TeachLogic IR = 0.8 ms.|
|Wall permeation: Because IR transmission is light based, it does not pass through solid walls.||Why permeation matters: Radio waves can travel through all adjacent rooms. This can create interference and/or inadvertently “leak” the communications into nearby rooms. IR stays in the intended room and conversely stays out of other rooms. Privacy matters.|
|Channel management: Because IR transmission stays within the walls, the same channels can be used in every room. The microphone is “paired” as soon as it enters the room.||Why channels matter: With IR, any microphone can work in any room. Radio systems require that microphones are manually paired in each room and will only work in that room unless unpaired and paired again in a new room.|
No Audio Dropout Guarantee
When a Sapphire microphone is used with an ICS-55 ceiling sensor, if audio dropout occurs in a standard classroom (enclosed classroom up to 1600 square feet with ceiling heights of 12 feet or less), TeachLogic will provide additional sensors at no charge.
To learn more about infrared or find a solution for your needs, contact us!