Day in the Life, A (Beatles) Easter Egg - Ultrasonic Dog Whistle

It was put there by John Lennon, not Paul McCartney. And if only dogs can hear it, why can myself and everyone I know hear it?

C-Miller, you can hear a faint ringing similar to that of a TV turning on, but you can't hear the actual pitch dogs hear, which is rediculously annoying and loud.

Most turntables and / or speakers are unable to reproduce frequencies above 20k Hz which is the threshold of human hearing (considering you are a new born without any hearing trauma)... thus this does not make sense. The "whistle" would have to produce sound above the 20k Hz range to be heard only by dogs or others animals.

cvan, it is true that humans can hear frequencies up to 20kHz, and that dogs can detect sounds well above our capacity (as high as 45kHz). But "silent" dog whistles don't even exceed 13kHz, which should be well within our audible range. The reason for this lies in sound pressure. Any sound above 10kHz must basically be "blasted" at a high decibel(dB) level for humans to hear, but a dog can hear the sound at even a low dB level. Therefore, a dog whistle, at 13kHz and 80dB may not be audible to a human, but will probably annoy the crap out of your dog. I haven't experimented with the record (or a dog) or anything, but Sir George Martin was (and still is) a musical genious. Inputting sounds such as these would have been no problem for him, even in the sixties with analog technology.

The whistle is audible on the CD, which may be what some people hear are speaking of. The reason you can hear it on the CD and not the record is because of the Sampling Theorom. CD's are sampled, turning an analog signal to to a digital and then obviously back to analog when you hear it. In order for waves to be converted without a loss of information (called aliasing) the sample rate must be GREATER THAN double the frequency. Because the dog whistle is such a high tone, it would be extremely difficult to sample at a rate high enough to keep it the same. Because the sample rate is lower than double that frequency, it is pitched down thus making it audible to the human ear much more clearly than on the vinyl record, which obviously does not need to be sampled.

The sound Paul put there was for his dog, Martha and all the dogs of London. (Paul wrote "Martha My Dear" for his dog.)