How is Gain Defined?

My new hearing aids (Audeo SMART IXs) have a +/-10dB setting on the remote. On the dB scale, shouldn’t 10dB mean 10X the gain? I would expect this to translate to 10X the volume, but when I turn the hearing aids up all the way I don’t even think they are twice as loud (well, maybe, but definitely not 10X). Is there a meaningful definition of how gain is to be interpreted for hearing aids? At 10dB, is there something that is amplified by a factor of 10?

Yes, it does (or not ? I’m not sure what you understand by “10X the gain”).

A 10 dB increase in sound intensity is a ten-fold increase. But don’t expect to “feel” the volume ten times higher :stuck_out_tongue:
If you feel it twice as loud, it’s perfect.

I always thought a 3dB increase doubled the sound pressure.

Audio Sound pressure is measured in DB SPL (Sound Pressure Level). Meaning: db SPL=10 times the log of P1 over P2. Where P1 is the measured power divided by the reference standard power which is the power of a whisper.

Plain db power is the often used to compare two powers…like saying something is 10db louder means that some sound is 10 times as loud as some other sound because for example: 10 times the log of 100 SPL divided by 10 SPL equals 10 and the log of 10 is 1…so 10 times 1 equals 10 or +10db.

And the normal (no defect) human hearing system works on a log scale. So twice as loud is just barely noticeable. It takes 10 times as loud to be perceived as approximately twice as loud.

Those hard of hearing with moderate to profound loss most often have Recruitment which means that they hear on a more linear scale…that is: loud sounds are much louder than what a normal hearing person hears. Ed

In a normal hearing person / ear: It takes +3 db (louder) for the first perception of sound increase.

A 1dB change is notionally regarded as barely perceptible.

I’m not sure if Alexander Graham Bell defined a dB in this way - but if so, it seems that he was a tad optimistic: a dB should have been nearer 1.5 dB.

I agree - that is the way I learned it.

Here is a pragmatic description of human loudness perception:

“Most people have difficulty distinguishing the louder of two sound sources if they differ by less than 1.5-2 dB. Research into the human perception of changes in sound level indicates that:
• A 3-dB change is barely perceptible;
• A 5-dB change is clearly perceptible; and
• A 10-dB change is perceived as being twice or half as loud.
A doubling or halving of acoustic energy will change the resulting sound level by 3 dB, which corresponds to a change that is barely perceptible. In practice, this means that, as a general rule, a doubling of traffic volume on a roadway, doubling the number of people in a stadium, or doubling the number of wind turbines on a wind farm will result in only a 3 dB, or barely perceptible, increase in noise.”