Music frequency = voltage frequency?

Frequency in Hertz (hz) is cycles per second.

Typical Middle C tone is around 440hz.

Typical US 110V AC current cycles at 60hz which is not very musical but would be a low bass tone.

4 cyl 4 stroke engine (2 exhaust pulse per revolution, assuming RPM range of 600-6000 RPMs) produces tone range of 20hz to 200hz.

8 cylinder produces almost exactly double that 40hz to 400hz, and hence it sounds more musical.

Anything that does something regularly at an interval can be measured as a frequency, such as the frequency of a single hand clapping, or the frequency with which trees fall in the forest.

Yes, the sound frequency can be converted into voltage frequency, and back. That's how microphones, electric music instruments, and amplifiers work.

Not sure what your question is. Frequency is the number of times something happens, from the number of buses per hour to the number of bits per second. There may, or may not be a correlation between any of them; most data can be tweeked to show what you want it to, of course.

Both musical sounds and electricity can be measured in the number of cycles per second (cps or Hertz - nothing to do with car hire...) which is their frequency.

sound frequency is changed to a voltage by a microphone

the voltage frequency wil be the same as the sound frequency

it is transmitted by some means (CD/tape/radio)

the voltage frequency is directly changed to an equivalent sound frequency by the loudspeaker

No, the voltage frequency is constant.

Music frequency = frequency of the sounds that musical instruments and singer's vocal cords emit

look on the spec for the stereo - no remember if it is 60HZ then i'd evaluate an inverter which will generate 60 Hz to power it - maximum modern electronics is geared up to attend to the two 50 and 60Hz enter, so a stepdown transformer could artwork . you will seek for suggestion from the Bose website besides to work out what they propose...