A peculiar scratching noise emanates from my digital piano prior to the ringing of my mobile phone. Is this interference harmful to the electronics of the digital piano and vice versa.

is your mobile phone on top of your digital piano ?

No, next to it or maybe even a few metres away from it

well , that's good

Move it farther away and let us know what happens

what mobile phone and what type of digital

Yamaha P-60 and Nokia 6620 Greg cc The range is about 5 metres or so

FCC ratings and approvals are supposed to prevent this kind of thing. Never heard of this before.

That is a very nice cell phone

I have the Motorola Razr , about 3 feet from my Rd700sx and Korg Tritons and i get zero interference

I did get the same exact ' frequency ' noise with a 3 yr old siemens cell phone and the Bose stereo in my car

It did not do any harm, it was just slightly annoying

why not experiment with a friends cell phone to see if you can duplicate the problem ?

I hear this happen a LOT teaching college students in a group piano classroom. Often, they will try to explain (embarassed) that they had the phone on "silent" mode, but indeed some sort of interference took place between the phone and the keyboard amp.

Seems to happen to my students up to about a meter away from the keyboard. I have little knowledge of whether this is endemic to a particular brand of phone-- I'd doubt it.

this happens with speakers and TV and lots of other things.... even with my TV on mute, it still did it so i think it has something to do with the speaker itself. although im not sure about weather or not it could be harmful.

Happens all the time with mine for years, nothing I've owned has ever been damaged by it.

The important thing to remember here is that cell phones are actually radios - they have a transmitter and a reciever. The transmitter section is usually dormant most of the time (i.e. it's not transmitting) but the reciever is always active. It's almost impossible to predict how two particular devices will interact, what with intermodulation of all the frequencies involved.

Putting the cell phone on "silent" mode does not do anything to the transmitter or reciever, it just turns off the ringer (and maybe activates the vibrator motor instead). If the phone has an "airplane" mode, that will shut off the transmitter but leave the reciever active (or shut both off depending on the phone). It's normally the transmitter that causes the interferance, but in general cell phones are noisey, dirty little buggers that deserve to be kept away from most other electronic devices.

I've actually seen a laptop computer set off someones pager. Turns out the laptop memory and video chipset was running at 166MHz and the pager was on 165MHz. The reciever in the pager has a pretty wide filter, so that 1MHz diff was close enough to set the pager off.

I doubt it will damamge anything, but if you are recording with a computer, using MIDI, etc I would keep my cellphone as far away as possible. That MIDI cable has another name in the radio world -- ANTENNA!

Always use shielded cables whenever possible. Don't waste you money on that Monster cable stuff, just get a good shielded cable.