Unlike some other circumstances where original aids are “confiscated” to enforce usage of the new units, I was allowed to keep my behind-the-ear instruments. With the exception of BodyPump, I have not worn them since. The bone anchored unit is definitely my method of first choice. One does get used to having lumps of perspex wedged in ones ears and bits hanging over them, but I was pleasantly surprised by just how much I appreciate them not being there now. I have no feedback trouble due to jaw position etc. and, at the moment, don’t need to fiddle with volume settings at all. I can experience feedback from getting things very close indeed to the unit, but due to the positioning this is far less frequent and intrusive. Actual contact seems more likely to cause feedback. The only regular occurrence of this is if I start to nod off in my favourite wing backed chair, I am roused by a noise I imagine to be very similar to accidentally sitting on a large cat.

The only reason I resort to my waterproof aids for the gym is that I don’t think the Baha would cope with the combination of copious sweat and unusual head positions involved in vigorous exercise. (My apologies to those of a sensitive disposition, we inhabit a real world)

The power available was at first disappointing. It still is a little, and the jury is still out on this. Users have to adjust every time there is an improvement in amplifier technology. A good quality output signal usually means less extraneous “white noise” generated by the amplification process itself. Unfortunately users adjust to this instrument noise and start to expect it as a sort of base load signal. In this case better quality is always perceived as lower volume.

In spite of the unit being on one side only I’m not particularly aware of having a “good side” for hearing, possibly because bone conduction feeds to both ears. Common sense logic does apply however. If being very analytical, I do hear things better (in both ears!) to the left than to the right.

The unit has a “directional” setting designed for use in conditions with a great deal of background noise, always very difficult for aid users. It seems very clever, but I’ve only had one chance to try it so far, on the first day. It does seem to be extremely directional, at close quarters being able to pick a single person out of a group. It also seems to filter out a lot of lower frequencies though, and everyone’s voice goes up a pitch or two. There also seems to be some loss of power as well, but we might be back at the ‘quantity vs quality’ balance again. It seems a very useful tool but one that I currently need more experience in using.

One major drawback is using an ordinary telephone. Like many aid users I knew just how to use my conventional instruments and was actually more confident on the phone than face to face. At the moment I am having trouble finding and holding a comfortable “sweet spot” for the position of the telephone handset. On the other hand I can now use a mobile phone quite well, whereas my conventional units suffered very badly from interference from the radio signal. In the past I could only use mobiles though a special induction loop system which required an inconvenient amount of extra body wiring.

The Baha does not have an induction circuit, which are common in many instruments and detect special signals in banks, theatres and other public places etc (when these are working well enough!!!!!). I won’t miss this for public systems but I do at home. TV is often a great problem for hearing impaired people and I had rigged up a private induction system that gave me better than standard hearing on my old units. (The family often had to turn the volume up from my settings so that they could hear comfortably). I can now hear reasonably well at normal settings with the Baha. but have to concentrate more.

One last note that may change some of this. Although I do have a Baha, it is the department demonstration unit, not the one obtained for me. At my first interview it was noted that I was right handed, and an assumption made that the unit would be positioned on that side because of the dexterity required in fitting. On the day of the operation I opted for fixing on the left as a personal preference. Because the units are directional, they are also ‘handed’. The system had not picked up my last minute change and had ordered a right hand unit. It will take about a week to obtain a replacement unit.

My last check up visit was a very quick affair with everything still going as planned, and a statement that the aid unit will definitely be fitted during my next visit. That is still a couple of weeks off yet. The only change in the routine is that I have been told to stop twice daily use of the general purpose ointment, and in future to only apply it “every so often”. I failed to get any really objective scientific definition of this frequency, so I am applying it when it comes to mind but only if I can’t really remember the last time I used it. It seems a suitably lackadaisical, non compulsive sort of regime.

Life has continued very much as normal, including gardening in some fairly fierce cold winds, and another hair cut. Hardly the stuff of prizewinning blogs.

Posted below is a recent photograph of the abutment, which unsurprisingly doesn’t look much different to the first one. The graft still looks fairly pink in this photo but not perhaps as ‘angry’ as the previous one. I think that is due basically to bad timing on my part. In general I’m told that the graft site is now much paler than it used to be. If you look at my ear and neck you will see that these are also quite a bit pinker than the last photo. This was taken quite soon after a heavier than usual gym session then a shower. I hadn’t realised that the effects remained visible for quite so long.

Modern moulds have to be a good fit into the ear canal and remain in position under difficult circumstances. The ear canal is very close indeed to the jaw’s “hinge” mechanism and is continuously flexed by the jaw and its muscles during speech and eating. The outer ear and canal together form a complex three dimensional shape, and making a nearly exact matching shape that can be inserted and removed relatively easily is challenging. All ears are different and insertion can be difficult, particularly with a new or especially deep mould. The action is a bit like a bayonet light bulb fitting, but with four stages instead of the bulb’s simple two stage – push then turn.

A poorly designed mould (or one that is not quite inserted correctly) can quickly cause extremely painful pressure sores. These form by the same mechanism as bed sores and are caused by continuous pressure at one localised point. They can be initiated inadvertently by many very minor changes, but are easily corrected once the cause is found.

With ‘behind the ear instruments’ amplified sound is channelled through the solid mould by a replaceable plastic tube. This passes through a duct drilled during the later stages of production. ‘In the ear’ aids are more complex, the moulds being produced as a hollow shell into which the entire instrument is assembled.

One very well known drawback of hearing aids is feedback. Also called ‘whistling’ and a host of other descriptive terms. Another very similar effect used to be the ‘howling’ common with poorly set up public address systems and microphones at local ‘hops’ etc. It is caused when amplified sound from a speaker has a relatively direct path back to the microphone. This causes some sensitive frequencies to be amplified even more, and round and round they go!

With hearing aids the microphone and speaker are, of necessity, extremely close together and feedback becomes increasingly difficult to avoid as the level of amplification is raised. Digital aids are much better at controlling this effect than the old analogues but a well fitted mould is still a major requirement for good operation. It must seal off any air path from the sound output to the ear drum, back to the microphone. Even with a good mould, feedback is still possible if anything (or anybody!) is placed very close to the aid. This is due to a different, sound reflection, mechanism. Even when part prepared, you can bet that an aid will always start to scream at the most inconvenient time when working in a very awkward position. Under a car bonnet, or wiring under the floor are obvious examples that come to mind immediately. The reader can perhaps imagine others.

The seal of the mould in the ear is so important, yet so difficult due to movement of the jaw. Moulds made from hybrid materials are now common in an attempt to combine the rigidity, required for good location, with flexibility for a good seal. In this case the bulk of the mould is rigid but with the innermost tip being a more rubbery formulation.

Moulds sealing as well as this can lead to their own problems. They don’t cause infections but they do constitute an unnatural environment in the ear which can incubate any existing problems. Remember many people, such a myself, are wearing aids due to damage caused by chronic infection effects. Condensation can also be a problem with behind the ear units, as the sound tube acts as a very efficient condenser particularly in cold weather. Droplets of condensation blocking the tube can cause sudden loss of hearing and cannot be removed without removing the aid. Also a drop of condensation running back into the ear is harmless but intensely irritating.

For these reasons ‘vented’ moulds are available for people who have a persistent condensation problem. After all I have said above about feedback and a good seal, I have no idea how this can be accommodated. I can only assume that the vent channel follows an indirect path and somehow emerges pointing away from the microphone area.

Pretty clever things really, all being considered.