Hearing aid direct audio input
Many hearing aids can handle direct audio input (DAI), often via a "shoe" that attaches to contacts on the aid itself. This shoe then provides a DAI jack (sometimes called a europlug or eurojack) that cables can be plugged into.
There seems to be a complete lack of cables designed for people with a single hearing aid, so one of my upcoming projects will be to convert a Y-cable that can serve two hearing aids into a joint DAI/earphone cable instead.
DAI connector pinout
The DAI connector has the following pinout:
- short/thick pin: ground
- long/thin pin: VDD (apparently -- doesn't seem to actually be connected to anything on a 3.5mm cable)
- short/thin pin: signal
Remember that a standard 3.5mm audio plug has the following pinout:
- tip: left signal
- inner sheath: right signal
- outer sheath: ground
Next stage: connecting an earphone to the plug on one side of the cable, to see if there are any impedance issues, although the cable I am using (an fmGenie one) is a very low-impedance cable because I have an Oticon hearing aid. Measured with a multimeter, it seems to be around 0Ω, so I think that's good enough for me. I believe attenuated cables have a 330kΩ resistor in series with each signal line (according to Neil Ferguson's bluetooth hearing aid hack page).
My ultimate goal is to get hold of a DAI jack that I can solder directly to an old earphone, so that I can just plug the spare DAI cable into the earphone directly, almost as if it were a hearing aid itself. Unfortunately, it seems that it is impossible to get hold of such things. According to Connevans, DAI jacks are only custom-made for hearing aid shoes. After some discussion, it seems like I should be able to make one myself though (with some help!) so we shall have to see how that turns out.
No more exams!
So my exams have finally finished... it's a very surreal feeling. Still got the project to go, but my time at university is even closer to being over. I don't think it's really sunk in yet.
Once the exam was over, a group of us headed to get some drinks, and came away with four bottles of cheap champagne sparkling white wine ("We've just finished our exams and want quantity over quality. What have you got?") and headed to the Union to consume it. Sadly things got slightly out of hand there, but I eventually headed back home after completely failing to work out how I could get to Camden (because I managed to completely forget the Tube existed).
Came back after the post-exam celebrations to find these stashed in the kitchen:
My cider has arrived!
So, next stop: project. The due date now seems incredibly close!
Life moves on
Wow, it's been a long time since I've updated anything here. Insight is moving along, but has currently stalled while I'm in exam mode. I'm not going to talk about that though — this is a rare personal post.
The End Is Nigh
... and that's it. No more lectures. Ever. Apart from revision lectures, but they don't count in the same way. This feels like a bit of an anti-climax. It's hard to believe that four years at university are almost over! It's going to take some getting used to.
Of course, it's not all over just yet - there are still exams to go.
Insight: First report done!
Well, after much hard work, criticism, and more: the first report is in! I'm actually only writing this post two weeks later because once it was done, I just had to take some time to catch up on everything else I've been letting slide while working almost non-stop on this report.
This report has outlined a number of my thoughts and decisions, and one of the last ideas to be considered for inclusion in the report was the issue of backwards compatability with existing systems. I have decided to follow the examples given in the paper by Gifford et al. on semantic file systems. I'll be describing this in more detail soon... I promise!
Anyway, I've decided to make the Insight Outsourcing Report available here for anyone that's interested. Once I get the time to deal with the site as well, I'll give it a more obvious home.
Back at Uni
So, I'm now back at University - it feels good to be back! I've moved back into the same house as last year, with the same guys as before, which is great. They're a wonderful bunch, and we live more like a family than a collection of students.
Today was the Freshers Fair, and it was great to see a lot of people again after six months away. I saw a few people from the department, as well as some other very good friends and my dance partner. It's amazing to realise just how much I've missed everybody, and how glad I am to be there with them again. I'm really going to miss this place when I leave this year.
My Life: The Musical
OK, another personal post: my girlfriend told me to do this! Basically, you have to put your music player on random, with your entire collection, and (being honest), choose each random track as it comes and put them next to these headings in order:
Opening Credits: I Just Can't Wait To Be King (The Lion King)
Waking Up: This Time Next Year (Sunset Blvd)
First Day At School: Orinoco Flow (Celtic Chillout)
Falling In Love: When You Are Old And Grey (Tom Lehrer)
Fight Song: From Russia With Love (Ballroom Instrumental)
Breaking Up: Could We Start Again Please (JCS)
Prom: A Whiter Shade of Pale (Procol Harum)
Life: Be Lucky (Show of Hands)
Making babies: Land of the 1000 Dances (Ballroom Jive)
Mental Breakdown: I Hold Your Hand In Mine (Tom Lehrer)
Driving: The Music of the Night (Phantom)
Flashback: Memory (Evita)
Getting back together: No Questions Asked (Fleetwood Mac)
Wedding: Read 'Em and Weep (Meat Loaf)
Birth of Child: Por Una Cabeza (Carlos Gardel)
Final Battle: I Can Hear Music (Beach Boys)
Death Scene: Hushabye Mountain (Chitty Chitty Bang Bang)
Funeral Song: Santiago (Show of Hands)
End Credits: All I Ask of You (Phantom)
... I think my music player knows things that I don't. What's more worrying is that I didn't cheat: that was the actual list. Whether you believe me or not, I know I'm not lying. I'm worried.
First day of work!
Well today was my first day at my 6-month work placement. I was pleasantly surprised by how quick the admin stuff was to sort out. I got all my passwords and usernames and everything (aside from a few hiccups). I'd even been receiving email since February, which I thought was quite impressive. Add to this my shiny brand-new computer, just for me to set up exactly the way I want, and I'm happy. Oh, and I can even use Linux if I wish. Hurrah for a corporation that understands these things 
Exams are over
Well that's it: exams are over. For better or for worse. Now off to do some drinking, I think...
Revision
Revision officially sucks. Well, I suppose it's ok; I just wish I had more time in which to do it. There just isn't enough time to revise all three courses for tomorrow today. Argh. At least I have 5hrs or so tomorrow, 8am-12:30pm. Then it's solid exams for the next three hours, and then it really will all be over. Scary thought! Anyway, to bed for the next 5 hours or so, then off to study again.
Noise-cancelling headphones are bliss.