Ah yes, the old speech volume regulation problem. I'm shite at this. It's an ongoing challenge. As a child I had "so called friends" tell me I was too loud in various ways to bully me so I'm hugely sensitive about it and can find being told I'm loud very upsetting.
Whether it's bullying or not is a harder line to draw. My personal experience is that it's about HOW the "you're being too loud" is handled. I've been both bullied and in situations where my speech volume is hurting other people's ears or clashing with sound sensitivity of people with autism or mental health issues which I don't want. If I know it's a problem I try and agree a "how they let me know" and that they may need to give me a few tries to get it right and I do sometimes have to talk at a volume I can't hear well to manage it.
I wonder if there are other issues than just this disagreement about your speech volume between you and boss. It seems odd that having talked to him and told him his approach is upsetting that he hasn't changed it, or been clear the speech volume remains an issue and you as a pair have to find a solution... Just telling you on IM again isn't helpful. It's hard to gauge from here whether boss is annoyed because it's different "and speaking loud is bad mmkay mindless (social) rule following" or if he's annoyed because he's genuinely finding it disruptive or painful to be in the room with you while on phone... He may not entirely have a self-aware sense of this himself of course. I know when my excolleagues all worked in our own offices except 2 who shared the sharers couldn't both be on the phone at the same time.
Realistically if your speech while you're on the phone is so loud boss can't get his work done then that is a work-disruption problem even if you don't intend to be loud. Disability rights in terms of rights not to be discriminated against, reasonable adjustment, freedom from harassment/victimisation are not absolute, they're qualified by how genuinely disruptive the "undesirable" or "socially normally unacceptable" disability-related behaviour is. The legal focus would have to be on what steps the employee and employer had considered to try and mitigate the problem but ultimately if the behaviour is genuinely disruptive to the business or other employees then it can in worst case be used as a legit reason to terminate contracts IF all other reasonable alternatives have not been successful.
It sounds like you have tried methods to reduce your volume but not had much success and boss's reaction to your speech volume is now causing anxiety to you which is reducing your work efficacy. No one's happy and there needs to be some serious discussion about options with sensitivity and openness on all sides.
I have a few ideas:
* Does your streamer has a 3.5mm jack socket on it? Mine (Oticon) does and I've found that Bluetooth to PC is SUCH an arse that I am better off just going back to sodding wires. I have a split out audio/speakers cable to replicate a headset on PC using the streamer.
* Could you plug in something like
https://www.sarabec.com/phoneplus-telephone-handset-amplifier-p38/ to your 'digital' phone? I've got one plugged in line with the handset which uses standard phone sockety connectors on a SNOM 300 VOIP phone thing downstairs as my likely "phone solution" when my beloved Geemarc Screenphone (now unobtanium) dies.... I can then either use the handset which is amplified more and has tone control, or I can plug my streamer into the amplifier unit directly which gives me the clearest sound.
* Is there any option to switch offices to work alongside someone who is less bothered by your loudness on phones? Can you do phonecalls somewhere else e.g. a meeting room? Could work provide you with your own office as a reasonable adjustment so you're not worried about your phone volume? Would they let you do some work again from home as a reasonable adjustment? It is worth nothing that as a
reasonable adjustment managementTM cannot say "but no one else is allowed to work from home" or anything about comparisons with other colleagues. If it would resolve the phones issue and they're not willing to consider an own-office for you, then they would be hard pushed to refuse it if you have historically and successfully worked from home.
* Access to Work might be worth trying again, if nothing else so you can demonstrate to EmployerTM that you are "trying all the things" and it would then be down to them to refuse to contribute to more tech, or for you to try more tech which still didn't work (if you wanted to make an own office or working from home again case).
For what it's worth I think most fairly deaf people struggle with voice volume, those like you and me who aren't too loud are far too quiet which has other problems.
