A mind less ordinary » Life

Hearing aid direct audio input

Dave — Mon, 16 Nov 2009 22:59:16 +0000

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!

Dave — Fri, 16 May 2008 10:00:09 +0000

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

Dave — Wed, 23 Apr 2008 00:01:39 +0000

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.

I've been looking around for jobs recently, as I will need something to bring in money after I finish at uni in just over two short months. I had originally planned to work for a company based on Slough with one of my housemates, until I received an offer from an ex-Oxford entrepreneur friend. After meeting this friend and his team within just a day or two of the email, I was very excited at the possibility of working with them, especially as I kept having ideas or suggestions for them.

I knew I would have to wait a while for their response, as they had to okay it with their board, and they weren't planning on deciding on a new hire for some time. As the days fluttered by towards the deadline for this other company and these friends flew out to Silicon Valley for Web Mission, I grew more nervous, hoping that they would get back to me with at least some sort of reply... until yesterday.

I had a phone call (at 7:45am his time) from my main contact there saying they would like to make me an offer! I was overjoyed at this, and was told we'd have a chat later that evening with details. Later that evening, and after some thought, I decided that this definitely was the right path for me, so I resolved to accept the offer.

It is with great pleasure that I announce that I am now the fourth member of the GroupSpaces team I start on or around 30th June, and I'm really, really excited about it! I'll be moving to Oxford, and living and working there. I can't wait to start!

Exams begin soon, though. 30th April - 15th May.

The End Is Nigh

Dave — Fri, 07 Mar 2008 11:00:41 +0000

... 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!

Dave — Wed, 23 Jan 2008 19:42:29 +0000

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

Dave — Tue, 02 Oct 2007 17:18:03 +0000

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.

Anyway, I was on a stall for Imperial Entrepreneurs at the Freshers Fair, and it was fantastic - I personally talked to loads of people and handed out lots of flyers. We had about 200 people sign up, which was more than we'd hoped. With any luck, we'll see most of those at our launch event on 23rd October. I really enjoyed talking to everyone and trying to convince them to join. Happily, there were a few who asked to join the moment I said "hello", which even I can't credit to myself.

On a more personal note, I also signed up as a staff member of the brand-new Website and Software Society, and they seemed really excited to have me on board. I may perhaps do some lecturing later this year for them on various subjects, which will be fun. We also had some contact with the new student media conglomeration, Mosaic, as we know some of the people behind it. I won't say any more on that for now though. Finally, a woman appeared out of nowhere on the IE stand, asked what we did, then told us she was a local resident and wanted some part-time computer work done. Naturally, the details got handed to me, so we'll see where that goes...

My Life: The Musical

Dave — Tue, 10 Apr 2007 21:09:42 +0000

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!

Dave — Mon, 02 Apr 2007 23:37:27 +0000

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

Dave — Sat, 24 Mar 2007 16:36:20 +0000

Well that's it: exams are over. For better or for worse. Now off to do some drinking, I think...

Revision

Dave — Fri, 23 Mar 2007 00:38:26 +0000

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.