4.7 should be 6kHz. We typically test from 250Hz up to 8kHz (in mostly octave intervals) to give a broad idea of how someone is hearing across the spectrum. Testing above 8kHz is rare as there is very little speech information that is contained in that area and "we are primarily concerned with communication abilities" of our patients. Bull **** as far as I'm concerned. I happen to be one of the few people in the field who believes that more testing should be performed - given my obsession with "high end audio" (ok fine, high end for MY budget), it is no wonder that I am livid re: modern day hearing aids and their sound quality. This is in some way, shape, form going to be my research topic although I don't have an official question yet.
The cochlea is tonotopically arranged (arranged by frequency) starting at the apical end of the cochlea. It begins at the higher frequencies and goes to the lower frequencies. Average range of hearing is 22/20kHz down to roughly 20Hz with frequencies down to about 15Hz being somewhat detectable, although not officially "audible." Even if the noise is primarily low frequency, it still has to travel through the high frequency portion which is part of the reasoning behind why higher frequencies are affected by noise first. As an aside, noise induced loss is typically 1/2 to 1 octave above the frequency of the noise and then spreads from there over a great deal of time due to the resonance of the ear canal.
As I already talked about the cochlear amplifier, I will continue from there very briefly. Medial to the cochlea, the auditory nerve caries information up to the cortex - for simplicity sake, I'm skipping A LOT here. The nerve is also tonotopically arranged, as is the cortex when signals finally arrive. When I mention that I'm skipping things, let me just say that the auditory system is the only system in the body that can take a finite set of stimuli and produce infinite outcomes - mostly cause of the stuff I've skipped.
Going back to the outer hair cells very briefly, as I think I mentioned before, they are essentially a non-linear amplifier controlled by the efferent nerve system. Their direct function can be measured through what is called, "Otoacoustic Emissions," or OAE's, which occur as a bi-product of introduced sound to the ear. Basically the sound comes back OUT of the ear around 50-70dB below the input sound - which can be either clicks or tones. Clinically Distortion Product OAE's are used most often (as they can be elicited with a slightly higher degree of hearing loss). They are the cubic distortion product of the input tones. Formula: 2f1 - f2 = CD. Things preventing sound from coming back out of the ear - debris, ear infection, etc - will affect OAE measurement.
When testing ones hearing, we test through air conduction - the little insert earphones placed in your ears - and through bone conduction which is a big black object placed behind your ears. When doing this, we are essentially skipping the outer and middle ear to measure hearing sensitivity through direct stimulation of the cochlea. Things which will cause differences between the two results include: middle ear infections, middle ear tumors, **** stuck in peoples ears - pencil erasors, M&M's, marbles, etc.... You'd be surprised as to how many of the later we see with kids. The middle ear cavity has an opening which "dumps" to the back of the throat known as the eustacian tube. This tube acts to relieve pressure buildup of the cavity.
Aside from hearing sensitivity tests, we test the middle ear reflex which will give an idea as to the condition of the stapedial (one of two muscles of the middle ear) reflex. This test is the tell tale sign of a recruiting ear. The principle of the reflex is basically:
1. loud sounds activate an action potenial up the 8th cranial nerve
2. from here it can go one of three places:
1. ipsilateral superior olivary complex
2. contralateral superior olivary complex
3. contralateral facial nerve nuclei
3. down from any of these sites to either the ipsilateral or contralateral stapedius through the 7th cranial nerve.
If there is an ilicitation of the reflex below 65dB(Sensation Level), then it is considered to be a recruiting ear. I've seen people with hearing thresholds down to 45dB who had reflexes at 110dB which means they were not recruiting. Recruitment really only kicks in when the outer hair cells are on their way to completely gone. If I had to put a percentage for your audiogram, I'd say 0-2% gone depending on earphone placement/debris (as described briefly next paragraph). Have you ever had any IV antibiotics (answer this in a private message if you'd like) as these can be ototoxic and can cause loss different than what is initially seen in an audiogram. If this is the case, OAE monitoring should be performed to measure hair cell (dis)function prior to it appearing on your behavior audiogram.
Looking at your audio, there is absolutely nothing wrong with your hearing. Hate to tell you this. The 10dB asymmetry in your ears in the high frequencies is probably due to placement of the insert earphones, or can even be caused by debris if it was occluding your ear canal. I've experienced this myself and I can hear a difference between ears - sounds a little muffled. But people are remarkably plastic (adaptable) and you'd get over it pretty quick. Presumably, reflexes were done on you, in which case, you either have or don't have a recruiting ear(s). Whether or not you have the results of the entire test battery I don't know - although if you do I'd be happy to discuss them with you in a private message as I don't want to discuss your medical history more in public. You can also call the doc and request that he give you all the information, at which time I'd also be happy to discuss it with you in private.
As to the popping, this is overstepping my scope of practice as I am not a medical doctor, but you could probably try some over the counter allergy meds to see if that makes a difference. This will decrease the swelling of your sinuses and presumably alleviate the popping sensation that arrises when the E-Tube opens.
As a rather random aside, I'm curious where you came up with the 62dB number? The reason I ask is that 60dB is not loud at all. In fact, long term average speech falls within 55-60dB(SPL) with a crest factor of 30dB (peaks and valleys around +12 and -18dB respectively) which would mean that you're ear drum flutters as you put it all the time.
If I were you, I'd find an audiologist who didn't work for an ENT and have a full evaluation, including reflex, tympanometry, OAE, and diagnostic hearing test.
That explained, I can elaborate on anything that anyone is interested in....
-D
