Volume Control

Why do the numbered volume controls of TV go up to 63? Why not 60 or 70? Would 3 dB or 7dB make that huge of a difference? What is the significance behind the value 63 in the first place?

0-63 is a range of 64 units, or 2 to the 6th power. In the digital age making things in powers of two is a simple, obvious choice, you know, binary and everything.

BTW, your volume control is only indicating the range of 64 steps from minimum to maximum, not decibels. An increase of 3dB is in fact a doubling of the apparent sound level. So it would be a big deal.

0 to 63 is represented by 6 bits in the digital world. That gives you some clues about the internal design of your TV.

Well, actually 3 dB is the smallest increase or decrease in level that could be detected

The pixies automatically posted for me before I was ready. Damn them!

To continue -

The response of the ear is logarithmic so the change in sound level that is detectable depends upon the level of the sound that is impinging on it at the time. If the sound level is 1 mw/cm[sup]2[/sup] then in order for a change in level to be detected it has to be at least 3 dB, or a change to 2 mW/cm[sup]2[/sup]. And from that new level, the intensity would have to change to 4 mw/cm[sup]2[/sup], or again 3 dB. And then to 8 mW/cm[sup]2[/sup] and so forth until the threshold of pain is reached. I wouldn’t recommend going beyond that although those who are in the car next to me with their window rolled down seem to have done so.

No, commasense has it right. Doubling the sound intensity is a 3 decibel increase.

I simulposted with your second post, I will think on what you said.

This site says that 1 dB is the minimum detectable difference.

I think it depends upon the method of measurement. If you are listening to a sound and the level is changed I think it is easier to detect a difference than if the sound is turned off and then back on at a different level.

On the other hand, the bandwidth of an audio system is defined as the frequency span between the frequencies at which the power output is 3 dB down from the center (geometric mean) frequency. I think this is on the assumption that it takes a 3 dB change to be detectable so in an audio system sound levels within the 3 dB bandwidth would be accurately reproduced as far as the ear is concerned.