Sound detection

Go To Last Post
10 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hello everyone,

I am a certified American sign language interpreter in my state and also coordinate various free electrical services for my local Deaf community.

During a recent conversation with a Deaf friend he mentioned that he has no way of knowing whether or not his vent fan is on for his stove. I began pondering an electronic solution. A microphone with a simple amp and a bandpass filter for the fan frequency would work right? Then I could simply use a row of LED's for each sound detection frequency, but I was wondering if the bandpass solution would work for all fans and how interference may affect the accuracy.

Some of you may remember a long time ago when I tried to use microphones to detect horns and sirens while driving in traffic. This was also a "Deaf aid".

In an effort to simplify the process I have even considered tuning forks modified inside a coil for each specific frequency rather than using microphones...this is where your mind takes you when you are not an electronic engineer!! lol

Any thoughts would be appreciated!

Thanks
John

Just some guy

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Piece of yarn tied to the grill will flap in the breeze when fan is on.

Imagecraft compiler user

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

With the proliferation of smart phones, i'd suggest getting an app written that gives, say a polar diagram of frequency and level using color. One would think, after some training, that a deaf person could distinguish the type of sounds by the pattern shown.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Is the fan integrated into the stove/oven. Or is it in one of those over the range hoods?

If it is in the stove it could be a little tricky

If it is in the hood them why not connect a neon indicator lamp to the fan switch and drill a mounting hole into the hood for the indicator?

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:
Piece of yarn tied to the grill will flap in the breeze when fan is on

That's how they built the pyramids:)

Quote:
With the proliferation of smart phones, i'd suggest getting an app written that gives, say a polar diagram of frequency and level using color. One would think, after some training, that a deaf person could distinguish the type of sounds by the pattern shown.

Kartman that is really an awesome idea!! I will investigate it further, thanks!

Quote:
Is the fan integrated into the stove/oven. Or is it in one of those over the range hoods?

If it is in the stove it could be a little tricky

If it is in the hood them why not connect a neon indicator lamp to the fan switch and drill a mounting hole into the hood for the indicator?

Jim, I am not sure - I can tell you that they want me to have someone come into their Deaf Club and separate the light and the fan in their restroom so they can turn the fan off. They operate on a limited budget and do not want the exhaust fan running 24/7. The simple fix is to add an additional switch, but I might migrate the solution into broader use.

Kartmans solution above is pretty great - there is probably already an app available...still, this would be a great learning project for me if I could find an effective way to delineate between the sounds...

Thanks everyone,
John

Just some guy

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

John,

We have the fan operating on a push button timer... installed after our son decided that the fan needed to be on all the time... but I was the one paying the electricity bill :lol:

And our range hood already has a neon to indicate the fan is working.

Ross McKenzie ValuSoft Melbourne Australia

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Thanks! After Kartmans post I gifted AUDIO ANALYZER through itunes to my Deaf friend!!

Smart devices have made almost any innovation I could do obsolete - for $7.99 US!!

Thanks John

Just some guy

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I would think "listening" for the acoustic signature of the fan would be more difficult than one might at first imagine. I would think the frequency spectrum is rather broad, and varies from fan to fan, and from installation to installation. (For a smart uC project, would need a FFT/DFT, spectrum analysis / matching, etc. Perhaps a "learning Mode", and a normal running mode. Doable, but not trivial.)

Although the smart phone app appears to be a viable solution, I'm not sure how "useful" it will be in practice. If one has to walk up close to the fan to "listen" to it with their smart phone, and study the screen, then why not just look at the on/off switch while one is standing there?

I would guess the goal is to attract one's attention visually to show that the fan is on, when one isn't standing right in front of the fan.

Another option might be a small MEMs type microphone mounted to the fan hood. Use it to detect the vibrations of the hood. Put your finger on the hood and I suspect you can feel the hood vibrate quite easily. (Or mounted to the case magnetically clamped to the fan hood.)

An op-amp front end feeding an ADC and a uC, all stuffed into a small box, magnetically clamped to the fan hood and you are done.

The micro "filters" the MEMs microphone's signal to ignore transient noise, (door closure in the room, etc.), and look for a minimum signal threshold for a minimum duration before turning on the LED.

Flash the LED with a 30% duty cycle and you just tripled the battery life.

LED is visible flashing from anywhere in the kitchen, bathroom, etc., wherever the fan is.

Just another thought for you to consider.

JC

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Thanks for sharing your thoughts Doc!!

Merry Christmas all!
John

Just some guy

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:
Another option might be a small MEMs type microphone mounted to the fan hood. Use it to detect the vibrations of the hood. Put your finger on the hood and I suspect you can feel the hood vibrate quite easily. (Or mounted to the case magnetically clamped to the fan hood.)

Instead of microphone why not an accelerometer? I think will be easier, when you have a constant vibration the fan is on.
Another option can't be measure the fan current? Or just detect voltage an turn on an led near the fan? This led can be on the fan's switch and near the fan.

Regards,

Bruno Muswieck