We have been looking at the issue of hearing Audio Everywhere in environments that also have a PA (public address) system. Our streaming audio system is the best out there in terms of minimizing the delay introduced by the Wi-Fi and mobile phone components, but even so, the delay difference is noticeable when there are two audio paths to the ear, in this case one through Audio Everywhere to the phone and the other one through the air from the speakers. Optimally the difference in delay would be less than 15 or 20 ms, but that is rare.
So when the difference is large, what is the solution that works for Assistive Listening? It is to have one of the paths be much louder than the other. One way to do this is to turn up the volume on the Audio Everywhere system, but that may not be comfortable, or even safe. The other way is to attenuate the volume from the PA system for the Audio Everywhere user.
This lead us to look at what is available in earphones that block the sound. There are four quadrants to consider. One axis is, how much attenuation of the ambient though-the-air signals does one get? There are two important cases
- Casual attenuation such as one gets with consumer-grade headphones
- Systems designed to block the sound. Such systems often have an ANSI-certified Noise Reduction Rating (NRR).
The other axis is headphone style
- These are usually less expensive and intrusive, but are generally not hearing aid compatible.
- Over-ear headphones are hearing aid compatible but often more expensive, bulky, and may not be what some people want to wear in a public event.
That is the tradeoff.
Another point is that, from a latency or lip-sync standpoint, bluetooth headphones are not preferred. Plain old wire is fastest.
We did a quick Google search for headphone systems. Here are some that we found in two important categories. Note that we have not tested them ourselves.
Casual over-ear: Sony MDR-ZX110, Behringer HPM1000, Panasonic RP-HTF600, Sennheiser HD 4.205, Skullcandy Crusher Over-Ear. AmazonBasics Lightweight On-Ear Headphones. Just search for “over-ear” or “on-ear” plus “headphones.”
NRR earbuds: ISOtunes PRO, 3M Peltor, Plogfones Contractor. Search for “NRR earphones.” One set of mainstream earbuds known for their isolation is mk5 Isolator Earphones, with 35 dB or more noise reduction.
Do you have a favorite? Please let us know.