I am planning on building a headphone amp for someone with age related hearing loss using simple attenuation on the input with a fairly high gain opa 604 based amp to compensate for that, maybe x5 to x10 voltage gain. I think that once hearing loss starts affecting speech intelligibility (presence region) the highest frequencies are probably not recoverable so this is just a simple shelf filter with a six way switch to adjust the frequency range maybe starting at 1 khz up to 8 khz with a simple stereo pot to adjust the level of the higher frequencies. I’m not trying to get a complete fix just something that improves the situation for the television, films , music etc
Please let me know if there is a better way of doing this or if you have tried this and had any good results. Thanks
Please let me know if there is a better way of doing this or if you have tried this and had any good results. Thanks
I built a headphone amp for my father many years ago and used a very simple technique from an article in Wireless World. Firstly the HF boost is not easily achievable with opamp circuitry simply because the gain needed is so high... you might be surprised just how much boost is needed and how 'low' in frequency that boost needs to be at.
Post #23 here.
https://www.diyaudio.com/community/...setup-on-a-new-television.180101/post-2419559
Post #23 here.
https://www.diyaudio.com/community/...setup-on-a-new-television.180101/post-2419559
Thanks, that is all really interesting and just the kind of thing I am after. Was this helpful with speech intelligibility? I see you have used a narrow band pass boost to correct through the presence region with no attempt to recover higher treble frequencies, I think I may do this aswell rather than having 20 dB boost at 20 khz and above, I will rethink my circuit and see how I get on. Many thanks
Very much so.
A lot depends on the actual nature of the hearing loss but for an older person you might actually find they can hear nothing past even 1.5 to 2kHz and so even thinking about what happens above that becomes irrelevant.
You could try them with headphones and a low level frequency sweep and see at what point (frequency) they lose the sound.
This might give you (or the person) an idea. Two tracks, one original and one modified with the response shown. I just used Audacity to do this. The two 20 second tracks are attached and are MP3 files so should play on anything.
The original was attenuated by around 25db and then the response curve shown applied. Max boost is around +18db at 1.6kHz with everything from the notional centre line cut.
The original was attenuated by around 25db and then the response curve shown applied. Max boost is around +18db at 1.6kHz with everything from the notional centre line cut.
That is really helpful, I am really surprised that the hearing loss goes so low down the frequency range no wonder they lose speech coherence I will ask the chap to do a frequency sweep off YouTube I think there are a number of hearing tests available that will certainly frame the problem for me. I am still keen to include a number of frequency profiles via a dp6t switch so he can select which he prefers. I will be ordering parts for this in the next few days and I will let you know how I get on. Many thanks for the information
You're very welcome 
This might be useful, super easy to use, you just click the different frequencies and select a level that makes each sound the same as the reference 1kHz:
http://www.phys.unsw.edu.au/jw/hearing.html
These give an idea of normal age related hearing loss.
This might be useful, super easy to use, you just click the different frequencies and select a level that makes each sound the same as the reference 1kHz:
http://www.phys.unsw.edu.au/jw/hearing.html
These give an idea of normal age related hearing loss.