Need audio frequency converter.

Thread Starter

burtonbh

Joined Feb 23, 2018
3
As an older ET and Submarine Sailor I am unable to hear most audio signals and alarms. I would like to find or build a sensor that would pick up higher frequency alarm signals and put out a 500 cps - 1 kc output signal, while ignoring non alarm type audio.
 

Tonyr1084

Joined Sep 24, 2015
3,651
So you've lost hearing sensitivity in the upper ranges. Unfortunately there are many sources of audio in similar ranges and to build a discriminator that would pick out an alarm signal out of a cacophony of other similar frequency sounds isn't going to be easy. I bet you have Tinnitus. I have it too. In my case it was loud rock-n-roll music, and the fact that I played the drums. Also, I'm growing older as well but continue to resist the idea that I'm aging. My back aches, my sleep isn't as good as it used to be, AND my tinnitus has only gotten worse. I watch TV with the volume up (like my dad used to do) and when people talk, if they don't speak loudly or I can't watch their lips I almost always can't understand what's being said. Recently I did a job for a company - oddly enough, building parts for the Navy. I worked with a guy who had an accent (middle eastern, like Pakistan, not trying to be a jerk here - forgive me if I'm wrong) and most of the time I could hardly understand him. Largely because of my lack of sensitivity in my hearing.

A signal that will indicate an alarm. Mmmm. I know deaf people have flashing lights to indicate when the phone is ringing or when there's a doorbell, but those things are hard wired in. As for the phone, don't go thinking "How does a deaf person use a phone?" They have translation devices that turn speech into text - phones. Not sure what they call them, maybe TTS or something. Perhaps your alarm(s) can have a flashing light. In fact, the doorbells I've just recently installed not only ring they also produce a flashing light that flashes for about 10 seconds. Maybe a discriminator is not the way to go.
 

Alec_t

Joined Sep 17, 2013
10,446
pick up higher frequency alarm signals and put out a 500 cps - 1 kc output signal
What alarm signals do you have that are higher than 1kHz? I've not measured them, but I doubt if any of the alarms in my house have a primary frequency above 1kHz.
 

GopherT

Joined Nov 23, 2012
8,012
iPhone and most Adroid phones can be set to flash for alerts (ring and text messages).
Here are instructions for current iPhones.

 

Audioguru

Joined Dec 20, 2007
11,251
I could not hear many things so I went for a free hearing test. It was normal (for my age, I was 69). I have severe high frequency hearing loss.
They gave me demo hearing aids turned up just a little for two weeks, then a little more for two weeks then full high frequency boost that matched my hearing and I bought them happily hearing like when I was young. I have had them for 3 years.
That is why they make hearing aids.

Here is a graph of normal hearing loss with age:
 

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Thread Starter

burtonbh

Joined Feb 23, 2018
3
What alarm signals do you have that are higher than 1kHz? I've not measured them, but I doubt if any of the alarms in my house have a primary frequency above 1kHz.
Actually, you probably do. Most electronic alarms now days use Sonalerts, which are mostly in the high frequency audio range. I use hearing aids and earphones for TV. I worked in electronic rooms with many fan cooled pieces of equipment for 40+ years and lost my hearing of higher audio frequencies.
So you've lost hearing sensitivity in the upper ranges. Unfortunately there are many sources of audio in similar ranges and to build a discriminator that would pick out an alarm signal out of a cacophony of other similar frequency sounds isn't going to be easy. I bet you have Tinnitus. I have it too. In my case it was loud rock-n-roll music, and the fact that I played the drums. Also, I'm growing older as well but continue to resist the idea that I'm aging. My back aches, my sleep isn't as good as it used to be, AND my tinnitus has only gotten worse. I watch TV with the volume up (like my dad used to do) and when people talk, if they don't speak loudly or I can't watch their lips I almost always can't understand what's being said. Recently I did a job for a company - oddly enough, building parts for the Navy. I worked with a guy who had an accent (middle eastern, like Pakistan, not trying to be a jerk here - forgive me if I'm wrong) and most of the time I could hardly understand him. Largely because of my lack of sensitivity in my hearing.

A signal that will indicate an alarm. Mmmm. I know deaf people have flashing lights to indicate when the phone is ringing or when there's a doorbell, but those things are hard wired in. As for the phone, don't go thinking "How does a deaf person use a phone?" They have translation devices that turn speech into text - phones. Not sure what they call them, maybe TTS or something. Perhaps your alarm(s) can have a flashing light. In fact, the doorbells I've just recently installed not only ring they also produce a flashing light that flashes for about 10 seconds. Maybe a discriminator is not the way to go.
Noise canceling earphones are able to remove repetitive sounds so the circuit exists that could discriminate between alarms and other sounds. What is needed is to sense the repetitive tones above the desired frequency and trigger an output at a frequency audible to the person with the hearing loss.
 

Alec_t

Joined Sep 17, 2013
10,446
What is needed is to sense the repetitive tones above the desired frequency
A simple high pass filter would select tones above the required frequency, but the more difficult bit would be to distinguish wanted high frequency tones from unwanted ones. That would require some sophisticated processing, more practical in the digital domain than the analogue one.
 

sghioto

Joined Dec 31, 2017
1,038
Actually, you probably do. Most electronic alarms now days use Sonalerts, which are mostly in the high frequency audio range.
Noise canceling earphones are able to remove repetitive sounds so the circuit exists that could discriminate between alarms and other sounds. What is needed is to sense the repetitive tones above the desired frequency and trigger an output at a frequency audible to the person with the hearing loss.
Could you modify the alarm to sound a lower tone? If that's not possible I would measure the frequency of the alarm tone and use a 567 to decode. Add some delay circuitry or additional filtering to prevent false activation.
SG
 

Tonyr1084

Joined Sep 24, 2015
3,651
Perhaps a very very narrow bandpass filter can discriminate from most of the sounds. Then (and I'm reaching here) maybe something that can detect the difference between a square wave produced audio signal versus the far more common analogue signals in that very narrow gap.

OR you could produce your bandpass filter and tune it in to a very specific frequency. Then when nature throws a sound at you that falls in that specific range, it's likely it will pass through that range, whereas your sonalert will continue to produce the signal stable in that frequency. IF your detection circuit detects that frequency for longer than (oh, lets say) one second then it can trigger whatever it is you need to alert you to the alarm.
 

Alec_t

Joined Sep 17, 2013
10,446
Here's a suggestion for down-converting the frequency of a single alarm, if you can't connect directly to its sounder. No frequency filtering is attempted. It relies on placing a cheapo electret mic close to the alarm, so that it responds predominantly to the alarm and not background sounds. A trimmer allows the sensitivity (gain) to be adjusted. A switch allows the output of the IC, and hence the frequency-division factor (2, 4, 8 etc), to be selected. Standby current is minimal and is due mainly to the mic bias current. Output transistor choice would depend on speaker drive current requirements, and might need a preceding buffer stage to avoid overloading the IC.
FrequencyReducer.PNG
 

ericgibbs

Joined Jan 29, 2010
8,865
hi,
The mobile phone vibrator motors are inexpensive, perhaps instead of a beeper alarm, a vibrator device may get the job done.
E
 

BR-549

Joined Sep 22, 2013
4,938
burtonbh....Audioguru in post #7 is your best solution.

You can also build an audible alarm repeater. Can you build active filters, oscillators and amplifiers?

Sharp SDR software is free to download and there is a free audio spectrum waterfall display available with it. This will display and RECORD the audio spectrum of a microphone. And depending on sound card.....ultrasonic also.

Set off the wanted alarms and it will record and display the frequencies for you.

A narrow band active filter can provide a windowed switch function......to enable an oscillator that you can hear. You get the same alarm pattern....just at different tone.

If you want to explore and encounter unknown alarms......go with hearing aid.
 
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