Hello Everyone! It has now been over two months since receiving the brilliant BAHA on a band. Switching it on first thing in a morning has now become part of my daily routine and I have well and truly adjusted to the extra hearing in my ear. I now miss the BAHA when I do not have it on.
This is a long blog post so I will add a summary so that you can judge whether this is worth a read or not. In this blog post, I refine my audio set-up to improve the experience of listening to music with a BAHA on my left and headphone speaker on my right. I use a TV Streamer to improve sound quality over the Phone Clip by streaming an isolated signal to the BAHA in streaming mode and I use crossfeed to create a more natural listening sound.
Okay, to begin. As part of the phreak in monophreak (okay, not quite the same as the old telephony hacking but hey, bluetooth did not exist back then and I am still playing with signals), I have been trying to push the limits of mono audio technology right from the moment I received the BAHA. Following the rolling tumble weeds of information on the internet, my intentions were to improve my overall experience of using the hearing aid and document my progress.
As per usual, this is not a guide and I always include the same disclaimer. This blog post is just for educational purposes and not for profit. It is to add to the pool of knowledge out there regarding how people are using their BAHAs to enjoy sound. I will not accept any liability if you try out anything in my blog. I am purely documenting about my experience, how I do things and how it works for me but we are all different and hearing loss can have many causes, each presenting different challenges. You must consult and seek guidance from audiologist, not my blog. Never risk your hearing!
I am left side deaf (now with some hearing through the BAHA), right side working. Due to multiple surgeries, traditional hearing aids do not work for me and I have been living without hearing on my left for most of my life. On the left side, I have a working cochlea so a BAHA with conduction technology works well for me.
So, what have I been up to? TV Streamer
I enjoy listening to music synchronised through Rogue Amoeba’s Audio Hijack on a Mac using the BAHA and either an Apple AirPod or headphone speaker, typically an Audio-Technica ATH-R70x. I have documented this already and therefore will not rehash the process here. For my experiments this time round, I have been trying to improve the sound I am getting by extending the frequency which I can hear music through my hearing aid. I had a theory that the Phone Clip intermediary device may be limiting the sound entering my ear through the BAHA based upon details from the specification of the Phone Clip manual. As a result, I bought a second-hand Cochlear TV Streamer which is meant to be capable of a greater range.
To cut to the chase, I didn’t have much success with extending the range. My theory is possibly wrong but surprisingly, I still managed an improvement in sound quality. I say possibly wrong because the frequency range limitation could be down to my type of hearing loss or the limitation of the amount of conduction available through a BAHA on a headband (I will build upon this post and re-test when I have surgery for an Osia) but I did improve the overall quality of the sound and I learnt something new. The BAHA has a streaming mode which isolates the signal coming into the device (instead of simultaneous stream and live listening), giving a better listening experience. Of course, it is now getting colder in the UK and I have my windows closed so I will double check that the sound isolation is actually via isolated streaming and it isn’t the result of removing sound coming on from the now closed window.
To activate the streaming mode, I had to pair the BAHA5 with the TV Streamer and then hold down the button on top of the BAHA for about two seconds until I heard a chime. This then closed off external sound, giving direct access to the stream. I had a jump in sound quality through a purer signal.
Success!
Next theory, crossed feed.
I have been making music for a long time using my working ear. I chose the name monophreak originally because I constantly tried to find hacky ways in which I could intercept the mono signal and make it stereo based upon theory alone. In that respect, I think I did quite well but I won’t really know until my hearing improves through an Osia. I would use visual aids such as Izotope’s Stereo Imager to track the frequency ranges diagonally upwards in relation to the stereo image, with mono frequencies set to about 120hz. I would use Mastering the Mix and quite a few other tools too to get a decent stereo sound by closing off left and right channels or by switching to mono. All of this was pure application of theory without actually hearing or knowing stereo.
While making music, I would play with stereo by introducing crossfeed via DSoniq Realphones. The best way to explain crossed is that if you have a pair of speakers in front of you, one on the left, one on the right, you would also hear some of the sound of the left speaker in your right ear and vice-versa.
With my hearing, the BAHA is not so natural in this respect. To me, it feels more mechanical and robotic. While I find the BAHA brilliant and now cannot imagine life without it, there is something unnatural about the crossfeed. It certainly doesn’t emulate the natural ear in the same way I hear sound around me but it got me thinking from my mixing – what if I could introduce a natural crossfeed into the signal through software or hardware? and so my next phase of research and experimentation began.
Yet again, to cut a long story short, I have been successful and in my subjective opinion (with very little experience of stereo), it improves the listening experience. I managed to achieve this through both software and hardware. For versatility, testing and other features, I opted for a hardware solution but had good experiences through both.
I raided my savings, sold unused items on eBay and upgraded my DAC to an ex-demo RME ADI-Pro 2 FS R Black Edition and bought a second hand SPL Phonitor 2. While reluctant to spend money on something which I was not sure would work, I thought well – I have to start getting some information and just could not find anything online when I started out with my BAHA. I could always sell the amps if it did not work out. Thankfully, it all went my way and I absolutely adore my audio set-up.
To wire everything, I had to learn a lot more about headphone signals. Thankfully the kind people at Audio Science Review and SPL helped me work all of this out and I have attached a working diagram further down the page. Details of my post to Audio Science Review can be found by clicking here.
Phonitor 2, heat sink and RME ADI-2 Pro FS R Black Edition
I learnt some very interesting quirks about setting up the TV Streamer and pre-amps. First off
“Warning: Never connect a mono jack cable to the headphone output (front panel stereo jack). Make sure that the stereo jack is fully inserted, otherwise a short circuit might damage the headphone amplifier!”
SPL Phonitor 2 manual
Wow. Living in a mono world, I never realised that shorting an amp was even a possibility. I always used to just disconnect one of the headphone speakers and forget about it. After spending a fair amount of cash on the Phonitor 2, I did not want to break it or get any nasty sound surges through a short. Under no circumstances would I ever want to risk my ears.
The second thing I learnt is that when a TRS cable is split in two via a TRS to two TS signals (left/right), the channel on the TS signal travels on the left even if it actually the sound from the right. When wiring, I had to ensure that the signal is still going to be received.
The third consideration was that my AudioTechnica ATH-R70x headphones have a very high ohm rating which is a great in a unit like the Phonitor 2 but this will increase the signal too much on the TV Streamer with much lower resistance, which I needed to reduce.
It probably took me about two weeks of creating diagrams with potential solutions, contacting manufacturers and opening up cables to check that the runs were good. SPL customer support were incredible and I want to pass on a special thanks to Andre at SPL who was incredibly patient and supportive. His excellent knowledge helped me get there in the end.
Back to the diagram. My Mac connects to the RME over USB. The RME connects to the Phonitor 2 over balanced XLR cables. I chose an RME/Phonitor 2 combo due to the reviews at Audio Science Review for the RME DAC and from various other pieces of research which made me think that for my music making purposes, this particular set-up could be very useful. I control the left and right channel synchronisation through Audio Hijack and I use Audio Hijack to drop the volume from the RME left channel so that it is much lower when feeding the TV Streamer compared to my high impedance headphones. This works a treat and it is really handy to have a live reading from the VU meter on the front of the Phonitor 2 that confirms this. It is nice advantage of having the hardware. While the RME can also utilise crossfeed and is amazing for listening to music, for my music making and hearing aid calibration, I prefer direct control of the dials and switches on the front of the Phonitor 2. For mixing, I wanted a Phonitor 2 for the matrix and to specifically make use of mid/side isolation and direct left/right isolation. I have to learn about stereo imaging and thought these features could be very useful.
I then needed to split the signal. From the Phonitor 2, I have a TRS male – remember the quote from the manual – STEREO JACK only! to two TS female connector outputs. One TS for the left out, one TS for the right out. It does not duplicate two stereo signals which would be TRS to two TRS outs. For the left TS side containing the left signal, I then use a male 1/4 inch TS to male 3.5 jack into the TV Streamer. From the right TS, I bought a Audio-Technica ATH-M50/70 cable and ran that into my AudioTechnica ATH-R70x single headphone instead of using the original cable. This is because the ATH-R70x cable splits into two and I did not want anything dangling (and at the time, I was worried about any potential shorts). I cannot stress enough that you have to make sure you do not short the Phonitor 2.
When cabling the headphone side, a key piece of information I was given was to not to bridge the plus line. I was not 100% sure what this meant and so unscrewed my TS connectors to take a look. In the adapter I was using, I could see that they were soldered the same way and the part that I believed to be positive was not soldered. Therefore, it could not be bridged. Please note, I am not an expert and cannot conform this is accurate. You have to do your own research here. After treble checking the connections, I switched it on. All was good.
TS female – note that there is a plastic sheath further up the barrel.
On Audio Hijack, I always start with the sound off and then gradually increase but with the stereo speaker held away from my head so I do not get blasted. I could see the Phonitor 2 VU meters start moving and I could hear sound. I then repeated the process with my TV Streamer which is always active as it is powered directly from my mains multi-socket, surge protector.
I then held by BAHA away from my head and with the volume off, gradually turned it off and oh no, no sound. After checking cables and seeing the VU meter move, I knew signal was coming through. I tried connecting and reconnecting to the TV Streamer but nothing. I then looked at the manual and could not see what I was doing wrong so headed to YouTube where I found the answer. I had to put the BAHA in streaming mode by holding the button on top of the BAHA for about two seconds until I head the chime. Finally (with the BAHA still away from my head), I could feel it vibrate and adjusted the sound on Audio Hijack.
After initial calibration, I then started listening to music and all I can say is wow. Well worth the effort. I finally get a really good stereo sound even with my limited frequency range. My good ear fills in missing frequencies and I get a really good sense of space. The feeling of a synth, pad or high bass sound travelling from my right ear to the left and back again is just wonderful. I already had the Phonitor 2 stereo matrix with crossfeed turned on and it felt really good on the settings that arrived in the box.
There were some important things to note. One thing is that I had to be very careful with the calibration of Audio Hijack. The pre-amps I am now using are very powerful and I needed to capture all loud sounds coming in to the Mac, including switch off audio alerts. While setting things up, I received a telephone call which fell outside of Audio Hijack. It wasn’t exceeding danger levels of 80ish decibels due to how I had the volume dials on the Phonitor 2 but it was loud and it got me thinking that I needed to carefully expand the range of apps being caught by Audio Hijack. This included the system sounds. That way, I could confidently listen to music, make music and watch videos without being unexpectedly blasted. I chose a lower volume dial setting on my Phonitor which meant that if something ever does get through, it will not do any damage.
This volume is based upon my subjective interpretations of sound learned through the use of an Apple iPhone and Air Pod combo which I use to track decibels when listening to music. For me, this is generally around 45 decibels because I tend to listen at home in quiet environments and do not switch on music much when out and about as the background noise means that I need to push the volume louder. I am determined to protect my one working ear so avoid this. Interestingly, I think the BAHA could possible win again in these situations because when I am out and about, my none working ear will prevent outside noise going in and I will receive sound from conduction. I have not tested this yet though.
To access my listening Information to learn about decibels, I head to the following location on my iPhone:
Settings –> Health –> Headphone Audio Level
To learn about safe hearing levels, I added ‘Hearing’ to the Apple Control Centre so that when listening to music over an AirPod, I can live monitor the level of sound going in.
I also monitor my hearing chart over time. Apple have a really useful page about monitoring hearing levels through the following link (click here).
One final note is that if the signal to the TV Streamer drops below a certain threshold, it switches to stand by. When I mix music, there are times where the frequency range will not be picked up because I have an EQ set on my hearing aid via Audio Hijack. I then have to play a short clip of music and it switches back on again.
The very very final note is that I ultimately had problems with crossed on the Phonitor 2 introduced by the latency. So to compensate, I bought a small Lip Sync delay unit which output to the AudioTechnica with about 75ms and then switched this off in AudioHijack. That way, I was able to get the full benefit of the Phonitor 2, crossed and angle system..