Thumbs up! But, there’s more.
Passive “noise reduction” of course, is supposed to be 100% effective, to the point of allowing two F-4 engines turning up at 100% in afterburner, from five feet away without my ears catching fire from overuse. And, passive attenuation IS that effective. So, the myth that “active NR” is “as great or better than passive” and therefore a requirement, is more of, “just because you can”, engineering.
Think about it. If passive attenuation can effectively attenuate 160 Db, don’t you think it can also stop someone snoring nearby, a loud TV, yelling in this room, or even someone yelling at you from two feet away?? Of course it can, and common sense can’t deny that truth.
This is why most great sound engineers specifically design passive attenuation as, in most cases, the ONLY method for performers ear protection. Those same engineers also design their headsets after the isolation, and in or out of the ear, that attenuation is the FIRST consideration, (even if they add “active isolation” as well). Then and only then, do they start designing in the ADDED sound sources.
Today’s RIC in ear acrylic custom HA molds CAN provide nearly 100% sound isolation, that I’d bet rival what I actually used in the USMC when working on tuning F-4 engines, live, while standing next to them. (It was recommended to have both David Clark ear muffs and in-ear three flange ear plugs.) But, when I said that the HA molds “can provide isolation”, that also means that the open ports, which are designed into the molds to mix ambient sound and air from the outside sound, must first be 100% closed off. Once that’s done, (which I do on all my molds), your isolation is nearly seamless. But, this now causes a new problem, and I’ll talk later about that solution. The problem is that you now can hear the ambient noise around you, that were designed into the integral HA design.
Once you have 100% isolation, and have sealed out all the air using the RIC molds, now you can add your sound back in. Luckily, the specs you see on most all the receivers are dead wrong, as least the way it is presented. (I’ve got a few disputes out there with a few HA pros, so YMMV of why I firmly believe the following:) The specs given by the HA manufacturer, was for the HA SYSTEM, since a HA audiologist doesn’t really care what the raw frequency response of the raw speaker is, but only when “included as part of the system”. That system is tuned to specifically block most all sound below 100Hz, BUT ONLY block the AMBIENT sound that is picked up by the microphones! Either I’ve proven beyond a shadow of doubt that my Bluetooth sound through my Phonak Paradise HA receivers, goes at nearly the identical sound level from 1,000 all the way down to 8 Hz, or my brain has rewired all the 100-8 Hz sound to emulate perfect bass, and perfect music.
Why? Tthe “system” is the mike[s], amplifier, and the “receiver” (we consumers commonly refer to as a “speaker” or “headphone” or the sound producing part of a “headset”). That means they are trying to help the audiologist make mostly SPEECH work, and not music. In fact, most HA pros will be VERY specific about lowering your expectations and tell you, “So, HA were never designed for music, and only work really well and are tuned for speech. So, you will never ever get great sound from your HA’s.”
Hmmm, let’s examine that statement a bit, and see if that’s really true. Within the next few years, you are going add the choices of great Bose, Apple, Jabra, and many others that compete with all the HA vendors you see today. The hardware will be identical to the consumer version of their devices. Only the programmed software will be different.
As you probably know, the HA industry is being turned upside down by the “non-prescription” “sound amplifier” providers. And most importantly, Apple, Bose, Jabra, and all the “ear bud” folks are jumping into filling that gap themselves. How will they do that?? Well, from and engineering perspective, their only option is to start with their great sounding “consumer entertainment” earphones.
This is relatively easy, and many companies have already started dabbling a bit to capture that market, eventually. Jabra is one notable, and I’m guessing that this week’s CES in Vegas, will have a ton of new entrants. It will take a while though, for regulatory, marketing, and engineering reasons, before they will replace our HA and also continue to provide a great sound system for music at the same time.
First, music already sounds great. Most good buds will cover higher than most dogs can hear, and all the way down below the lowest pipe organ note, about 6-8 Hz. (No one can really “hear” much below 10 Hz with our ears, and we start sensing our “feeling” of the buzz added to our ear sensation.)
So, how do you turn Apple ear buds for instance, into HA’s? Apple’s buds have three microphones in them already, so they can do active sound isolation. Most of your best HA’s only have at most two mikes. So, since both HA’s and the buds are fully programmed with DSP chips, all you have to do is to reprogram the buds. (Easier said than done though, since the HA industry has been tuning and perfecting all the software to provide as nearly perfect HA’s as possible, for many decades).
Personally, I don’t think the buds that rely on active isolation will ever be as good as what I’m using with 100% passive isolation. So, I think they will need to add more physical, passive isolation. Remember, active isolation is just supposed to emulate what passive isolation provided, and there’s a bunch of “physics reasons” why they can’t do a 100% perfect job emulating passive isolation. (Think about isolating a jet engine next to your ear, Bose! Likewise 3D video will ever duplicate real life 3D from any 2D media, even if it is cool. Movie critics conclude 3D will never be more than a niche, for these “physics reasons”.)
– So, with fully 100% occluded acrylic custom molds, I’ve now got perfectly tuned music via bluetooth to my ears, from higher than I can hear, all the way down to 8 Hz. (I’ve tested with my phone’s BT, using a frequency generator. MY “perceived RWE measurement” results are that all frequencies seem to be equally loud throughout this range, at both a very low sound level, and also a very high sound level.)
My last remaining problem is that the ambient sound is now, almost totally lost. While it can adjust the balance and add microphone amplified sound back it, adjusting that balance is both inconvenient, and was never designed to sound great for talking or listening to TV. My workaround is to simply pull the molds part way out of my ear, and mute the music. More work should be done to solve this last part.
Without further engineering, listening to Led Zeppelin at full volume will almost always prevent you from hearing the person next to you, yelling to get your attention. This too, is likely working “as designed” to screen outside noise so we can be perfectly entertained. But, we still need an easy, convenient, and perfectly tuned way to switch modes from music, to speech, to phones. Whoever can provide that, will own both HA world and the CE world.