Hearing Loss
I have many thousands of hours on Chinook without any hearing loss whatsoever. I use the unaugmented Mk 4 helmet and each time I plug in, I have to turn down the previous occupant's intercom and radio volumes. Everyone seems to use CEP or VAMPS and I wonder if these devices, while cutting out background noise, force aircrew to turn up their volume controls and thus receive a higher peak volume at their ear. Will there be any long-term effect on their hearing as a result of this higher peak volume?
kintyred
Long time since I've done this, but as part of the Sea King programme in the mid-90s, and helmet mod 080, a new design of capsule padding was introduced. Aircrew were found to have consciously chosen ill-fitting (loose) helmets for comfort. But any airgap would increase the likelihood of the ANR feeding back (squealing). The intent was also to improve passive attenuation; and comfort and fit when wearing spectacles. You may have these better earshells. At the time mod 080 was mandatory for ASaC7 only, but inevitably other users would get new padding when it was due for replacement.
The final solution to the problem was to fund made-to-measure helmets; but I'm unsure how many took up the offer. I seem to recall they were about twice the cost of an ordinary Mk4, but nothing in the scheme of things. In the end, the entire AEW2 and ASaC7 ANR programmes were actually funded through Westland efficiency and us getting a rebate (as they're capped on profit).
Good question about long term effect. The quick answer is, intercom noise contributes a little to noise dose, which is measured against constant exposure over an 8 hour period. Intercom is harsh/peaky, given the typical tels frequency range of 300-3300Hz. But it's not constant, so is not necessarily damaging. ASaC7 had a new, excellent intercom design, with new high quality audio amps. A design aim was that one would have one's preferred settings on the Station Box (say, all pots at 12 o'clock) and it would be the same in any cab. Hitherto this was impossible in either an Ultra or SG Brown system, as the cheapo amps had too wide a tolerance. The new ones had a 'smoother' sound, and of course there was less influence from external noise. The other thing I recall is that the helmet transducers in a Mk4 are cheap crap. A decent one costs more than the entire Mk4 helmet.
Also regarding volume. Mod 080 mandated sole use of a single mic type. (Racal boom). Hitherto, AEW2 aircrew had a concession to use Socapex, if they wished. Anyone with a Racal boom, plugging in to a Station set for Socapex, would find it too loud, as the mic sensitivity was very different. Socapex was perceived as 'low noise', but using it meant you were overdriving the cheap amps. Signal level doesn't equate to quality.
Hope this helps.
Long time since I've done this, but as part of the Sea King programme in the mid-90s, and helmet mod 080, a new design of capsule padding was introduced. Aircrew were found to have consciously chosen ill-fitting (loose) helmets for comfort. But any airgap would increase the likelihood of the ANR feeding back (squealing). The intent was also to improve passive attenuation; and comfort and fit when wearing spectacles. You may have these better earshells. At the time mod 080 was mandatory for ASaC7 only, but inevitably other users would get new padding when it was due for replacement.
The final solution to the problem was to fund made-to-measure helmets; but I'm unsure how many took up the offer. I seem to recall they were about twice the cost of an ordinary Mk4, but nothing in the scheme of things. In the end, the entire AEW2 and ASaC7 ANR programmes were actually funded through Westland efficiency and us getting a rebate (as they're capped on profit).
Good question about long term effect. The quick answer is, intercom noise contributes a little to noise dose, which is measured against constant exposure over an 8 hour period. Intercom is harsh/peaky, given the typical tels frequency range of 300-3300Hz. But it's not constant, so is not necessarily damaging. ASaC7 had a new, excellent intercom design, with new high quality audio amps. A design aim was that one would have one's preferred settings on the Station Box (say, all pots at 12 o'clock) and it would be the same in any cab. Hitherto this was impossible in either an Ultra or SG Brown system, as the cheapo amps had too wide a tolerance. The new ones had a 'smoother' sound, and of course there was less influence from external noise. The other thing I recall is that the helmet transducers in a Mk4 are cheap crap. A decent one costs more than the entire Mk4 helmet.
Also regarding volume. Mod 080 mandated sole use of a single mic type. (Racal boom). Hitherto, AEW2 aircrew had a concession to use Socapex, if they wished. Anyone with a Racal boom, plugging in to a Station set for Socapex, would find it too loud, as the mic sensitivity was very different. Socapex was perceived as 'low noise', but using it meant you were overdriving the cheap amps. Signal level doesn't equate to quality.
Hope this helps.
Kintyred - everyone "seems to use CEPs or VAMPS" because their use is mandated (unless you follow the incredibly restrictive flying hours limits for an unaugmented helmet). As for intercom volume difference, you can't compare volume you experience in an unaugmented mk4 with CEP/VAMPs, as the intercom system is driving a different speaker and therefore has an entirely different volume at the ear for each device. Evidence from the Tutor fleet firmly suggests that noise exposure from the intercom/radio is lessened with CEP/VAMP due to the ability to turn the volume of the intercom down and still be able to hear it over the passively isolated background noise. The main problem I had on the Tutor with CEPs was that the stall warner became significantly less compelling as it was not integrated into the intercom, but instead was a buzzer in the cockpit.
FWIW, the evidence on hearing damage is pretty well established, though the studies and evidence on exactly how much hearing protection by helmet and passive augmentation gives you is somewhat contentious and depends on a number of factors including, as in Tuc's example, how well one's helmet fits! I know that in some areas airborne time with VAMPs is restricted due to the risk of exceeding noise exposure limits. The only two things I'd say in addition to "loud noise over a long time causes hearing loss" are:
a) everyone has an anecdote that bucks a well established statistical trend (grandma smoking twenty a day and living to 100 does not make smoking safer) and
b) ac noise is definitely lessened wearing augmented helmet (incl CEP/VAMP/ANR where type applicable) compared with a standard helmet.
Having, on my own ac type, moved from unaugmented to CEP, the difference in clarity of intercom is incredible and does lead one to wonder how we managed before! Every now and again (CEP failure etc) I fly without for short periods and that impression is reinforced.
FWIW, the evidence on hearing damage is pretty well established, though the studies and evidence on exactly how much hearing protection by helmet and passive augmentation gives you is somewhat contentious and depends on a number of factors including, as in Tuc's example, how well one's helmet fits! I know that in some areas airborne time with VAMPs is restricted due to the risk of exceeding noise exposure limits. The only two things I'd say in addition to "loud noise over a long time causes hearing loss" are:
a) everyone has an anecdote that bucks a well established statistical trend (grandma smoking twenty a day and living to 100 does not make smoking safer) and
b) ac noise is definitely lessened wearing augmented helmet (incl CEP/VAMP/ANR where type applicable) compared with a standard helmet.
Having, on my own ac type, moved from unaugmented to CEP, the difference in clarity of intercom is incredible and does lead one to wonder how we managed before! Every now and again (CEP failure etc) I fly without for short periods and that impression is reinforced.
Thanks Tuc,
Illuminating as ever!
I was on exchange with a NATO partner, whose aircrew used the US Army helmets and struggled to hear intercom and radio calls (SASless I'd be interested in your comments). I introduced them to Helmets International given my positive experiences of the Mk4 but the option was rejected on the grounds of costs. They opted for CEP, and I participated in their programme. I didn't find them beneficial.
pba
I'm not suggesting that my experience should be the basis for hearing protection. I merely point out that the Mk4 helmet can work in a very noisy environment, though not for everyone. I was just relating out my experiences and wondering about the consequences for using increased intercom/radio volumes.
Illuminating as ever!
I was on exchange with a NATO partner, whose aircrew used the US Army helmets and struggled to hear intercom and radio calls (SASless I'd be interested in your comments). I introduced them to Helmets International given my positive experiences of the Mk4 but the option was rejected on the grounds of costs. They opted for CEP, and I participated in their programme. I didn't find them beneficial.
pba
I'm not suggesting that my experience should be the basis for hearing protection. I merely point out that the Mk4 helmet can work in a very noisy environment, though not for everyone. I was just relating out my experiences and wondering about the consequences for using increased intercom/radio volumes.
pba
Thanks. All too new for me. As I said before, in-ear devices weren't wanted in the 90s, so the technical solution was ANR (or a silent main gearbox).
Apart from the reduction in noise dose, the other crucial test was speech intelligibility. One of the reasons (+ TEMPEST) why ANR was fully integrated into the comms system/aircraft, meaning the helmet became a comms LRU as well as an AEA. Farnborough have a dedicated lab, and local students were watered, fed and handed a tenner to come in for a session. They wore a helmet, it was fed with real aircraft noise from a survey, and they wrote down the words they heard. So, you could 'change aircraft' midstream. The main work in this area was done during Digital ANR development, which was completed in 2000, and led to adaptable software. I think it's one of those areas that will be forever in development.
Your mention of warning tones makes me twitch. Not integrated, no fly - that was the rule. Breaching that led to the loss of ZG710 in 2003. A fundamental part of the programme was checking all warning tones, and adjusting them if necessary. Conversely, one odd problem was the crews could hear the GPS ToD update tone every second, which was reduced.
It's success can be easily appreciated by one fact. Without ANR, AEW2 allowable flying hours were 59 per year. With Mk1 analog (simple, battery powered), 315. Post-padding upgrade, full integration (aircraft power, etc) and lessons learned from trials, 1350 in the front, 700 in the back. A good example of how big a difference seat position makes. Your friendly project team should have the equivalent data for current kit and aircraft.
Thanks. All too new for me. As I said before, in-ear devices weren't wanted in the 90s, so the technical solution was ANR (or a silent main gearbox).
Apart from the reduction in noise dose, the other crucial test was speech intelligibility. One of the reasons (+ TEMPEST) why ANR was fully integrated into the comms system/aircraft, meaning the helmet became a comms LRU as well as an AEA. Farnborough have a dedicated lab, and local students were watered, fed and handed a tenner to come in for a session. They wore a helmet, it was fed with real aircraft noise from a survey, and they wrote down the words they heard. So, you could 'change aircraft' midstream. The main work in this area was done during Digital ANR development, which was completed in 2000, and led to adaptable software. I think it's one of those areas that will be forever in development.
Your mention of warning tones makes me twitch. Not integrated, no fly - that was the rule. Breaching that led to the loss of ZG710 in 2003. A fundamental part of the programme was checking all warning tones, and adjusting them if necessary. Conversely, one odd problem was the crews could hear the GPS ToD update tone every second, which was reduced.
It's success can be easily appreciated by one fact. Without ANR, AEW2 allowable flying hours were 59 per year. With Mk1 analog (simple, battery powered), 315. Post-padding upgrade, full integration (aircraft power, etc) and lessons learned from trials, 1350 in the front, 700 in the back. A good example of how big a difference seat position makes. Your friendly project team should have the equivalent data for current kit and aircraft.
If anyone wants the Submission I was asked to prepare by DOR(Sea) in 1998, just ask. It was intended to be topped and tailed into an Air Staff Requirement, and specifically mentions both fixed and rotary, in all Services. Also, groundcrew. At the time, legal advice was 'the clock runs on litigation from now', as a fully integrated Helmet ANR system had been deployed (i.e. powered from, and part of, the intercom), and the Digital ANR was under development to bring the noise dose below the mooted 75dB(A). Other in-ear devices that have become popular were rejected by the Services at the time - ANR was the agreed solution. OR did not proceed. It was left to whoever had the gumption to do it on any given aircraft. Some of the above comments are true - few gave a toss and I'm glad the court has taken a dim view.
I'd say the date could be pushed back a few years, as the RAF had run a programme for Harrier in the 80s, but run up against the problem of miniaturising it to fit in a Mk10 (?) helmet. However, they gave up instead of committing more to the Applied Research Package. Sea King AEW & HC4 picked it up again in 1994, and it entered service in 1998.
I'd say the date could be pushed back a few years, as the RAF had run a programme for Harrier in the 80s, but run up against the problem of miniaturising it to fit in a Mk10 (?) helmet. However, they gave up instead of committing more to the Applied Research Package. Sea King AEW & HC4 picked it up again in 1994, and it entered service in 1998.
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Retired a couple of years ago after working for some 30- years in the back of a noisy ac. I first noticed
that my hearing had been affected, in my case tinnitus, when I could not hear the majority of 'beeps'
during my hearing test. I did not mention it until the doctor commented that my hearing was still fine.
I went back after 6- months for a further test and all was well they said. I now have constant high pitch ringing
in both ears. When I left the RAF I requested all of my medical records, but strangely enough there was no
mention of my visits.
that my hearing had been affected, in my case tinnitus, when I could not hear the majority of 'beeps'
during my hearing test. I did not mention it until the doctor commented that my hearing was still fine.
I went back after 6- months for a further test and all was well they said. I now have constant high pitch ringing
in both ears. When I left the RAF I requested all of my medical records, but strangely enough there was no
mention of my visits.
I also type listening to the bells......
I don't own this space under my name. I should have leased it while I still could
I got my med records last month. Took about 2 months - no charge.
The records were batched. There were some omissions where i had been sick away from base.
My first audiometry test was in 1981. I was immediately downgraded. Every subsequent test at my.annual medical was recorded though there were variations in some years. I must get round to checking year on year.
Before 1981 tests were down with the 'standard med assistant whisper down a dark corridor.
The records were batched. There were some omissions where i had been sick away from base.
My first audiometry test was in 1981. I was immediately downgraded. Every subsequent test at my.annual medical was recorded though there were variations in some years. I must get round to checking year on year.
Before 1981 tests were down with the 'standard med assistant whisper down a dark corridor.
